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PLUMBING
≈ FRESHWATER PLUMBING
Portable Water Systems
Water System Refits
Installation Tips
Maintenance
Grey Water & Seawater Plumbing
Seacocks, Thru-hulls & Valves
Bilge Plumbing
Scupper Plumbing
2
3
6
6
8
8
10
12
1
0
1
Archives
/
≈ ADDING A WATER HEATER
13
≈ RX FOR HEADS
HEADS: The front end of the sanitation system
DISPOSAL: The back end of the system
Step-by-Step Head Rebuild
Add a holding tank
Odor Control
MoreRoutine Maintenance
Head Troubleshooting Chart
15
15
16
17
18
20
21
22
≈ BUILD A MADE-TO-MEASURE HOLDING TANK
23
≈ INSTALL A PRESSURE-WATER SYSTEM
Reduce plumbing system noise
25
26
≈ KEEPING DRY BELOW DECKS
Types of Bilge Pumps
Pump Performance
Determining Pump Size
System Planning
Emergency Only Pumps
Installation Guidelines
Automatic Pump Switches
28
28
28
29
29
30
31
34
≈ HOSE CLAMPS - BUYER BEWARE
35
≈ EASY-TO-INSTALL BILGE PUMP ALARM
36
≈ BILGE PUMP REPLACEMENT
37
≈ WHAT YOU SHOULD KNOW ABOUT MARINE HOSE
38
≈ HOW TO PLUMB BENDS
41
© DIY boat owner 2001 1-888-658-2628
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PLUMBING 101
By Nick Bailey
If you, like most DIY readers, own
an older boat and are inclined
towards self-reliance, you already
know that plumbing seems to
account for more than its fair
share of trouble among the
onboard systems. It’s the little
things — all those fittings that
leak, pumps that won’t, potable
water that isn’t, diabolical heads
that always clog or smell, a
seized gate valve or broken thruhull (with sea water rushing in!) —
little, nasty things that can ruin
your whole day. And, it’s the
surveyor’s emphatic disapproval
of your scupper hoses or the
holding tank that is about to
explode because the vent is
clogged. “Run for your lives. It’s a
bomb!”
Furthermore, because the
boatbuilder originally installed
many of these items before the
deck went on or the twin V-8s
were wedged in, you can’t even
reach the offending parts, let
alone fix them. Never mind. If you
have the plumber’s prerequisites
of grim determination, double-
/ Back page / Next page / Contents page /
jointedness, a colorful vocabulary
and a basic tool kit, as well as
immunity from claustrophobia,
muscle cramps and the everpresent bilge slime (get a tetanus
shot), you are ready to take up
arms against any plumbing
problem.
This article will cover
plumbing for potable, gray and
sea water, and bilge and scupper
systems. We’ll discuss waste
systems, holding tank retrofits and
head maintenance in our next
issue.
POTABLE WATER
SYSTEMS
Potable water systems range in
complexity from a single, small
tank hooked to a manual pump in
the galley to multi-fixture hot-andcold-water pressure systems on
larger yachts that can even
include washing machines and ice
makers (Figure 1).
Around 1970, typical
equipment consisted of monel
(most common) and some
galvanized tanks and copper
plumbing,
often with a
big Jabsco
diaphragm pressure pump at the
heart of the system. In the case of
larger powerboats, a 24- or 32volt DC
electrical system was often the
norm. Faucets and fixtures were
not much different from what you
would find at home. Smaller boats
(under 10.5m/35’), especially
sailboats, typically were not fitted
with pressure water systems.
Throughout the 70s and into the
80s, however, as boatbuilders
encountered greater consumer
demand for “luxury” systems,
pressure water, hot water and
many other comforts of home
became more commonplace.
Nowadays, those “comforts” are
usually standard equipment in
boats over 9m (30’).
Galvanized tanks gave way
to experiments with integral tanks
in fiberglass boats (not always
such a great idea) and then to the
off-the-shelf plastic (polyethylene)
tanks commonly used today.
Copper plumbing was replaced
by reinforced vinyl “clear braid”
© DIY boat owner 2001 1-888-658-2628
2
PLUMBING 101
MANUAL COLD WATER SYSTEM
SINGLE- OR TWIN-FIXTURE COLD WATER (DEMAND PUMP) b
a
Vanity
Galley
*Manual
pumps
Vanity
Fill
Fill
Vent
Vent
*Pump type:
Manuak or
foot pump.
Some can also be
combines with an
electric pump as in (b)
MULTI-FIXTURE COLD PRESSURE WATER SYSTEM
c
*Electric pump located
below tank level
MULTI-FIXTURE HOT & COLD PRESSURE WATER SYSTEM d
Vanity
Aft Shower
Galley
Vanity
*Pump type:
Centrifugal or
impeller, may
or may not run
dry, most not
self-priming.
Water
Tank
Water
Tank
Galley
Fill
Fill
Vent
Momentary
switch
Galley
Optional
Accumulator
Pressure Switch
Water
Tank
* Electric
Pump
Vent
Nick Bailey
Cold
**Accumulator Tank
* Pump type:
Same as multi
fixture (d), but
can be smaller
capacity.
Filter
Ice
Maker
Optional
Hot Engine
Coolant
Pressure switch
*Electric
Pump
Filter
**Accumulator
optional but recommended
Hot
Water
Heater
*Pump type:
Self priming, cam
run dry (i.e.
diaphram type).
Figure 1
Sample water systems. A) manual cold-water system B) single- or twin-fixture cold-water system (demand pump) C) multifixture cold pressure water system D) multi-fixture hot-and-cold pressure water system.
hose which, in turn, gave way to
semi-rigid plastic pipe — often with
proprietary self-clamping fittings
such as the Whale System 15, FlairIt, Qest or Serkit systems.
Reciprocating diaphragm pumps
are still popular, though they are
being gradually replaced by rotary
multi-lobe diaphragm pumps such
as the Flojet Quad II (the originator),
Groco P-9000, Jabsco Par-Mate or
Par-Max, SHURflo Silencer and
Whale Evenflo pumps. These
pumps are usually quieter and less
expensive, yet offer the same
ability to run dry without damage
and self prime that is characteristic
of traditional diaphragm pumps.
Water at the touch of a button
is also available in simple coldwater systems by fitting an in-line
“demand” centrifugal pump that
can stand alone or “flow through”
and supplement an existing
manual pump.
Before proceeding with any
upgrades or repairs, however,
check your water system in detail
to verify hose or pipe sizes
(Figure 2), the size and style of
fittings and the exact model of your
electric pump, if you have one.
Refits
Most water systems leave room for
improvement, whether it’s
© DIY boat owner 2001 1-888-658-2628
3
PLUMBING 101
upgrading a cold-water pressure
system to full hot and cold water or
simply installing an in-line primary
filter before the pressure pump.
(This filter will eliminate problems
due to debris jamming the valves;
any pressure system without one is
bound to be troublesome.)
Here are some other upgrades
worth considering:
Modern rotary multi-lobe diaphragm
pumps, like The Silencer from
SHURflo, are quiet, can run dry
without damage and are self-priming.
Courtesy of West Marine
with a new rotary-type pump. These
are much quieter and some
manufacturers offer an inexpensive
rebuild kit for the old pump.
Figure 2
The following chart shows how
dimensions compare on various sizes of
straight tailpieces. Note that the hosebarb end of the tailpiece (A) measures
the same as its listed size, unlike the
pipe end (C) which is not related.
(Courtesy of West Marine.)
Size
A
1/2"
1/2"
3/4"
3/4"
1"
1"
1-1/4" 1-1/4"
1-1/2" 1-1/2"
B
C
D
5/16" 13/16" 2-1/4"
1/2"
1"
2-1/4"
13/16" 1-5/16" 2-1/2"
1"
1-5/8" 2-3/4"
1-1/4" 1-7/8"
3"
smooth out water delivery and stop
the annoying rapid on/off cycling
of the pressure pump.
2/ Replace the pressure pump
3/ Add a shower, whether it’s a
cold-only or a hot-and-cold-water
system, a cockpit or swim-platform
shower is guaranteed to be a
popular addition to any pressure
water system, especially after
you’ve been swimming in salt
water. Complete kits are available
from several manufacturers
(Attwood, Heater Craft and Whale
are just a few examples). The kits
incorporate a neat, recessed well
for the mixer assembly. Just make a
cutout in the cockpit wall or transom
and tee into your existing plumbing.
Make sure you know what you are
cutting into — you’ll want to miss
fuel and water tanks, wiring,
piping, or structural stringers — and
that you have enough room to run
the plumbing.
4/ Replace old faucets and
mixers. Many attractive units
designed specifically for boats are
now available (Barka, Scandvik,
SHURflo, Tempo and Whale are
popular makes).
5/ Add a secondary water filter. A
variety of in-line activated charcoal
filters are now available that can
improve your water by reducing the
impurities that cause bad taste and
odors. Most of these filters won’t
eliminate bacteria by themselves
and must be used in conjunction
with antibacterial tablets or
additives or another filter. One
exception is the New World filter
(#7054), which uses a three-stage
filtering process to remove bacteria.
Another filter unit, the Water Fixer,
also uses UV light to sterilize the
- Ti p Emergency Plugs
You should always have on
board a collection of tapered
softwood (pine or cedar)
plugs sized to jam into a
failed hose, a broken CPS
(Cheap Plastic S!*t) thru-hull
or when you have to
disconnect a hose and the
valve won’t close. Corro-sion
can lead to sudden failure of
a fitting, as can a lightning
strike. A lanyard threaded
through the plug is wrapped
around the base to keep
water pressure from pushing
out the plug. These plugs are
the ultimate plumber’s helper.
© DIY boat owner 2001 1-888-658-2628
Anne-Marie Hendry
1/ Add an accumulator tank. This
is an air-filled tank connected to the
discharge side of the pump. It will
4
PLUMBING 101
water. If you’ve got a case of really
stinky water, drain and sanitize the
system first (see Maintenance on
page 6). Water Fixer also sells an
in-line UV chamber that’s easily
retrofitted in a boat already
equipped with a filtration system.
6/ Electrify your manual water
system.
Option 1: Whale and Jabsco offer
small, in-line pumps complete with
manual switches that can either
work through your manual pump or
replace it. This is a simple
installation (though the centrifugal
non-self-priming pumps have to go
below tank level) and this type of
pump won’t be damaged if it
happens to be switched on when
the faucet is closed.
Option 2: By adding the
appropriate faucets and, if
necessary, upgrading the hose and
fittings on your system, it’s fairly
easy to install a pump complete
with an automatic pressure switch
and convert to the convenience of a
pressure water system.
7/ Add a manual backup. Install a
manually-operated pump in a
pressurized water system to ensure
that water can be drawn in the
event of a power failure. Tee the
hose for the hand pump upstream
of the pressure pump.
8/ Add a deep sink.
Older boats with shallow,
oval-shaped sinks are
easily retrofitted with
deeper high-quality
stainless steel rectangular
ones or double sinks; on some
installations the two basins may be
the same dimensions as a single.
9/ Install a tank monitor. These
units use everything from the oldfashioned dip stick to pressure,
sonar or electric sensors to read the
fluid level in the tank. Most work
well in water or fuel but are
unreliable in a holding tank. One of
the more dependable units, the
Tank Tender from Hart Systems,
operates on air pressure. You
simply pump air into the tank and a
gauge reads the amount of pressure
in inches of liquid. And since there’s
no wiring involved, these units are
easy to install. The all-new
electronic Tank Scan from Northern
Research can monitor up to five
tanks by means of a sonar sensor
mounted on the outside of each
tank, eliminating the need to cut
into the tank.
General Installation
Tips
Flojet’s 2840 with a Quad II rotary
diaphragm pump and accumulator
tank mounted on a plastic base makes
a compact package for pressurized
water installations on larger boats.
Any plumbing work leads you into
the question: “What size is it and
will this fit to that?” Finding the
answers to these questions is not
made any easier by the fact that
on any given size of NPT (National
Pipe Thread) fitting there isn’t any
threaded part actually measuring
that size (Figure 2). Hose-barb
diameters generally measure at
their nominal size but nominal
sizes for hose are based on the
inside diameter and bear no
relationship to the outside
dimension. On the other hand,
pipe sizing is roughly based on the
outside diameter.
Make sure the hose
or pipe you use is
food grade
(garden hose is
not
Replacing old faucets and mixers with
new, more-stylish designs is a
worthwhile upgrade.
acceptable). Clear PVC hose is
fine for cold-water non-pressure
systems. Clear braid reinforced
PVC hose is okay in hot-and-cold
pressure systems and is the least
expensive.
Many argue that despite their
higher cost, semi-rigid pipe systems
are the easiest of all to install.
Installation requires few tools
(Figure 3) and you won’t have to
struggle to jam stiff hose over barb
fittings or fiddle with hose clamps.
Soften the hose in hot water, then
rub a small amount of dish
detergent or Vaseline on as a
lubricant, or heat the hose end
evenly with a hair dryer until it
softens. Semi-rigid pipe won’t kink
as easily, either. If you do use semirigid pipe, however, plan very
carefully and be prepared to order
the fit tings in advance; few
retailers are likely to have
everything you need in stock.
Make sure all pumps are wired
following the manufacturer’s
directions and are fused properly.
© DIY boat owner 2001 1-888-658-2628
5
PLUMBING 101
So you don’t have pressure water
and don’t want to mess with your
shorepower or engine. In that
case, Nautical Innovations’ new
Hot Springs Water Heater may
be what you need. It’s a plastic
non-pressure-rated 15-litre (US 4gallon), 12-volt heater that uses a
100-watt DC element (8-amp
draw). This unit promises
lukewarm to very warm water,
32°C to 40°C (90°F to 105°F),
with a three-hour to overnight
recycling time, depending on the
temperature of the cold water
going in. It’s connected as an
auxiliary tank by selector valve to
a non-pressure system. This will
provide a couple of foot-pump
showers plus dishwashing daily
and is well within the
maintenance level of a small
battery charger (keep an eye on
your battery electrolyte levels). At
US$200, it’s a lot more civilized
than a solar-heated “sun” shower
water bag.
Atlantic Marine also offers a
100-watt DC element for its T
Series stainless-steel heater, best
fitted in the 15- litre (US 4-gallon)
model. This heater can be used in
a pressure system and has an
optional engine heat exchanger
(US$439 and up).
With wiring and plumbing, neatness
counts. Seawater hoses should be
top-quality fabric or wire-reinforced
rubber. It’s good practice to doubleclamp hoses (this is not always
possible) with clamps of all-stainless
steel (including the screw) fastened
so the screws are staggered (Figure
4). (The double-clamp rule applies to
all exhaust and fuel-fill connections
and, if possible, seawater
2
1
FIRST PUSH PIPE FULLY
INTO FITTING UP TO LINE
THEN INSERT U-CLIP TO
LOCK PIPE INTO FITTING
MEASURE LENGTH OF TUBING
REQUIRED FROM THIS POINT.
ENSURE END OF
PIPE IS CUT SQUARE.
TO REMOVE PIPE PUSH COLLAR IN
3
4
SNAP COVER INTO POSITION TO PREVENT
THE U-CLIP COMING LOOSE
AND RELEASING PIPE
CROSS SECTION SHOWING THE CLAMPING
SYSTEM WHICH FORMS AN EASILY
DISMANTLED LEAK-PROOF JOINT
Figure 3
Whale System 15 semi-rigid pipe system is easy to install and requires no tools.
1 Measure length of tubing required from this point.
2 Insert U-clip to lock pipe into fitting.
3 Snap cover into position to prevent the U-clip coming loose and releasing pipe.
4 Cross-section showing the clamping system which forms an easily dismantled
leak-proof joint.
connections mounted less than 15cm
(6”) above the waterline.) To prevent
leaks when the hose and adapter fit
poorly, or to seal existing leaks,
apply sealant to the adapter only
(Figure 5); do not apply to the
inside of the hose. Don’t use any
toxic sealants like 3M 5200 or other
polyurethane adhesive to seal leaks
in a potable water system. Using
sealants will make the removal of the
hose for maintenance or
replacement very difficult. Where a
hose passes through a bulkhead or
partition, you’ll need to provide
chafe protection. Use a rubber
grommet (if you can find one the
right size) or split a short length of
oversize hose, wrap it around the
system hose where it passes through
the bulkhead and secure with tape
or hose clamps.
For complex piping systems, it’s
a good practice to draw up a
circuit diagram showing the
location of hose runs, seacocks,
connections and wiring terminals.
File this in your maintenance log for
quick reference when doing routine
servicing or repairs.
Maintenance
Given proper winterizing, a
potable water system should not
need much maintenance other
than the occasional water-pump
service or repair and finding and
fixing the odd leak. If there are
foul odors, or if the system
becomes contaminated, disinfect it
American Boat and Yacht Council
Hot H20 DC
Alternative
Figure 4
Proper hose clamp installation.
© DIY boat owner 2001 1-888-658-2628
6
PLUMBING 101
temperature. If the water turns blue,
it may be unsafe to drink; drain the
tank and rinse it using the method
outlined above or another chlorinebased water treatment.
Figure 5
To prevent or seal existing leaks when
the hose and adapter fit poorly, apply
a non-toxic sealant to the adapter only
but take note: using sealants will make
the removal of the hose very difficult.
using standard household bleach
(typically a 5.25% sodium
hypochloride solution).
Exact instructions are given in
the American Boat and Yacht
Council (ABYC) standards
manual, appendix H-23; here’s a
brief description of the sanitization
treatment for water systems. (Keep
in mind that bleach may be tough
on rubber pump parts and it
should never be used in heads.)
Step 1: Flush the system with
potable water and drain
it completely.
Step 2: Fill the system
completely with chlorine
at 100 parts per million
and allow to stand for
one hour.
Step 3: Drain and flush
thoroughly with fresh
water.
Step 4: Refill with potable
water. If the tank still
smells like bleach, you
haven’t flushed it
enough.
You should also check your tank
regularly for bacteria with a watertesting kit such as WaterCheck.
Simply pour water into the bag and
let it sit for 24 to 36 hours at room
Rust is another common
maintenance problem on older
boats or steel boats with integral
metal tanks. Corrosion eventually
overcomes the galvanizing or
epoxy coatings, first causing rusty
water and then causing the tank
(or hull) to leak. If replacement of
the tank is not practical, it may be
possible to gain access inside,
grind or blast the corroded steel to
“near bright metal” and apply a
potable epoxy coating (white
Devo Barrust 235, available from
marine and industrial paint
suppliers, can be used in this
application). If the steel cannot be
reached to be properly prepped,
however, you’ll waste your time
trying to apply coatings over a
bad surface. If there’s even the
slightest pinhole in the epoxy liner,
the tank will start to rust and
eventually leak again. In that case,
it’s time to think in terms of an
auxiliary tank located elsewhere in
the boat, or to consider major
repairs — such as cutting out the
tank and replacing it with a
stainless-steel one. A flexible
“bladder” tank (they’re available
in many sizes) or a custom-made
epoxy-coated plywood tank fitted
inside the old integral tank is also
a viable option.
Polyethylene tanks that have
cracked can sometimes be
repaired successfully; replacement,
however, is the best option.
Pressure Water-Pump
Repairs
Rebuild kits with detailed
instructions are available for most
high-end pressure water pumps;
Adding a water filter will improve water
quality, reducing bad taste and odors.
This Water Fixer unit also utilizes a UV
light chamber to sterilize the water.
lower-cost pumps may not be worth
the bother. The most common
complaint is that the pump runs but
doesn’t pump; this is usually caused
by debris in the one-way valves
and dismantling and cleaning is all
that is needed. If the pump won’t
run, check the voltage to the pump.
If there’s no problem with the
voltage, the motor may be dead or
the pressure switch may be
malfunctioning. Using inadequate
wire gauges or too-small-diameter
hose will both cause motor burnout.
Try shorting across the switch to
see if the pump runs. If it does,
replace the pressure switch. If the
pump runs for a bit and then pops
the breaker, you could have a bad
pump motor, a weak breaker or a
blocked waterline. Disconnect the
waterline and try it again, then
check the line for blockage.
If the pump runs on and is not
shut off normally by the pressure
switch, you either have a big leak
- Ti p - Filler ‘er up
To prevent the heating element in
the hot water tank from burning
out when you recommission your
boat, fill the tank with water
before turning on the power.
© DIY boat owner 2001 1-888-658-2628
7
PLUMBING 101
- Ti p CONSERVE
WATER
Use seawater for clean-up jobs
in the galley. If your boat has a
washdown system, tee off the
discharge side of the pump and
hook up the hose to a manual
pump or a kitchen-type sprayer
mounted in a convenient place
in the galley.
or the pressure switch is faulty. If
the pump cycles frequently, you
have a leak you’ll need to find. If
the system is leak-free, replace the
switch. If the lights dim when the
pump goes on, either the pump is
drawing too much current and
you’ll need to upgrade the wire
size or you’ve got a defective
pump motor, a blocked waterline
or a weak breaker.
GRAY WATER
AND
SEAWATER
PLUMBING
Gray Water
Gray water is any waste water
other than the sewage from your
head. Typically, galley and vanity
sink drains are connected via hose
to a valved thru-hull fitting
(“seacock”) and the gray water
drains out the bottom of the boat.
This works fine as long as your sink
is well above the waterline.
Sailboats have another problem.
The sink that is above the waterline
when the boat’s at anchor may not
be when you’re sailing upwind with
the boat heeled 20°. Owners of
such boats soon get into the habit
of shutting off the seacock when the
sink is not in use; forgetting to do so
is not conducive to domestic
harmony — and adds
unnecessarily to the excitement of
cruising. When the drain is below
the waterline, as it often is with a
shower or in sinks in deep-draft
vessels, you must collect the waste
water and pump it overboard.
I have seen instances where
the whole bilge served as the
collection point for gray water.
With any extended use, however,
you will end up with bilge reek not
dissimilar to that in an 18th
Century frigate. That may sound
romantic, but it isn’t, especially if
some among the crew are already
feeling a bit green. A better option
is a small, easily cleaned
collection sump, or a tank with its
own automatic or manuallyswitched submersible or selfpriming diaphragm pump. This
sump accepts drain hoses from
one or more fixtures. While
showering or draining a sink, you
switch on the sump pump and the
pump’s discharge overboard will
usually stay ahead of the
incoming flow of waste water.
Better yet, if the pump has a float
switch, it will turn itself on. Any
submersible pump or pickup
strainer in the sump or gray water
tank will require occasional
cleaning to remove hair and other
debris, so you must be able to
gain easy access to the sump.
SEACOCKS,
THRU-HULLS
AND VALVES
In general, hull “skin fittings” and
the hose systems connected to
them are critical components,
whether they are draining waste
water out or letting fresh water in.
The following anecdote provides
an example of some of the little
things that can sink you.
In the summer of ‘75 in
Toronto, Ont., the influential owner
of a new 9m (30’) sailboat built by
a well-known and reputable
Canadian manufacturer received
a call from his downtown marina.
It seemed that his boat had
inexplicably sunk at its mooring.
After salvage, the builder’s
representatives discovered that the
threads on the white metal nut
holding the galley sink tailpiece in
place had been machined a bit
too thin and the nut (a 65-cent
item) had split, letting the now
disconnected sink drain hose and
tailpiece fall just below the
waterline (glub, glub, glub).
Subsequent boats from this
manufacturer all have a piece of
wire holding up the tailpiece and
a little tag on the companionway
drop board that reads “Good
seamanship dictates that all
seacocks be closed when leaving
the boat.” This was a lesson
learned — fortunately, no one was
put in danger during the learning.
You should carefully check
your own below-waterline
hardware and think about things
that might cause a sinking. Hoses
should be top quality, securely
clamped and replaced
immediately if they become
cracked or weathered. Hose
clamps should be all-stainless.
Seacocks, thru-hulls and valves
should be fiber-reinforced plastic
(such as RC Products Marelon
fittings by Forespar), or bronze or
stainless, but never brass nor CPS
(Cheap Plastic S!*t!). Many boats
sink every year from thru-hulls
made of delrin or CPS. Impending
failure is evidenced by cracking
and crazing on the outside flange.
Often, the thru-hull is sealed with a
© DIY boat owner 2001 1-888-658-2628
8
PLUMBING 101
HANDLE
PACKING NUT
MAIN BODY NUT
THREADED ROD TO
RAISE AND LOWER GRATE
Jim Sollers
SLOT IN VALVE BODY
Figure 6
Gate valves fail without warning —
they seize easily, the stem breaks if
forced and debris prevents the gate
from closing. Replace all valves below
the waterline with quarter-turn ball
valves.
non-compatible sealant that
attacks the plastic. Better to
replace all CPS thru-hulls.
Seacocks should be quarterturn ball valves because they are
faster acting and less likely to
seize. Gate valves (Figure 6),
recognizable by the “tap” handle
that is turned to open or close the
valve, are a poor choice on a
boat since you can’t tell at a
glance if they are open or closed.
Furthermore, the gate that raises
and lowers inside the valve as the
Figure 7
Marelon fittings are better than bronze
units as they don’t corrode and require
less maintenance.
handle is turned can easily be
prevented from seating properly
by debris, the valve seizes easily
and the stem is easily broken off if
forced. A worthwhile upgrade
project is to replace all gate valves
with quarter-turn ball valves. When
you’re installing new or
replacement seacocks or valves,
be sure their operation isn’t
hindered by other fixtures or
hardware and that they are easily
accessed for maintenance.
Marelon fittings (Figure 7)
have been on the market now for
many years and, in many ways,
are as good as bronze units with
the bonus feature of being immune
to galvanic corrosion — the grim
reaper of any underwater metal.
Be careful which way and with
how much torque you apply to a
Marelon handle or it will break.
Keep a few spares on board. Tip: If
a Marelon valve jams, back off the
large assembly nut until the handle
turns (about one turn), then slowly
retighten the nut while turning the
handle until you feel resistance.
Seawater (raw water) is often
in demand on board — for engine
cooling, head flushing, galley
prewash rinsing, deck washing,
air-conditioner cooling and so on.
If you are adding a new seawater
fixture, avoid the temptation to tee
it off the engine intake. This could
cause your engine coolant pump
to suck air at a critical moment
and overheat (leaving you with an
expensive repair). You can safely
tee off your gray-water outlets,
though you may find your new
pump clogged with hair or bits of
galley trash. Our next issue will
look at the particular requirements
to handle seawater without
siphoning and overflow of the
head. If your head is below the
waterline, this again can cause
sinking.
- Ti p REVERSING THE
FLOW
For sailboaters only: Does
water flow into the sink via the
drain when your boat heels —
either when sailing or
grounding — rather than out
of the sink? Install a one-way
check valve in the drain hose.
Maintenance
All seacocks and valves need
yearly lubrication and inspection.
The traditional seacock has the
thru-hull and valve as a single unit
utilizing a tapered plug and seat
either in-line or at right angles to
the axis of the seacock. The plug
has a hole in it which lines up with
the outlet in the seat when the
seacock is open. Such units have
a lot of moving metal surface in
contact and can get very stiff if not
well greased. At least once a
season, disassemble each
seacock and lubricate and repair
as necessary.
BILGE PLUMBING
The bilge pump is on one hand a
convenience and on the other a
critical safety system. There are a
surprising number of boats that
rely on their bilge pumps —
planked wooden boats that never
quite took up after launch;
runabouts with leaky covers and
badly scuppered cockpits;
inboards and auxiliaries with
dribbling stuffing boxes; and many
others. If left unattended and not
pumped they either promptly sink
or sink after the first all-day
rainstorm of the season.
Many people rely on their
© DIY boat owner 2001 1-888-658-2628
9
PLUMBING 101
automatic electric bilge pump to
keep their boats afloat without
even being aware they’re doing
so. This is a dangerous position to
be in because, sooner or later,
every bilge pump stops working.
(Of course, working in the marine
service industry may cause my
opinions to be biased; I don’t get
to see the reliable pumps!) Float
switches jam or fail, batteries dry
out or go flat, pumps burn out or
are clogged with debris or rust
which never sleeps.
If you are planning to install
an electric bilge pump consider
the following. There are basically
two types: submersible centrifugalstyle pumps (from Attwood,
Depco, Groco, Lovett, Mayfair,
Rule, SHURflo, Vetus and others)
and non-submersible self-priming
diaphragm types (such as the
Flojet LF-12) with a strum box or
screened pickup in the bilge. All
bilge pumps require some kind of
strainer or screen to prevent
fouling of the impeller in the cage
of the submersible unit or the oneway valves in the diaphragm
pumps. Either type can be
controlled by an automatic switch
or manually triggered. The nonsubmersible unit has an
advantage if access into the
deepest part of the bilge is difficult
(in deep-V boats, for example).
The submersible has the
advantages of lower cost and, in
some big models, very high flow
rates. Both types can run dry
safely, although the submersible
pump bearings will eventually
overheat if they become dry.
Lovett pumps are the only
submersible units that are UL
approved, meaning they meet
minimum vibration, shock and
safety requirements.
Bilge pumps must be mounted
on a flat surface and fastened
securely with self-tapping screws,
a good underwater adhesive or by
clamping them to a bulkhead or
stringer. Refrain from using the
corrugated hose typically sold for
bilge-pump use. The price is right
but the corrugations slow down
the discharge rate — according to
Tom Hale, technical director of
ABYC, the hose reduces outflow
by as much as 40%. The smooth
“cuffs” on the ends located every
foot or so also don’t allow enough
room for two clamps. Smoothwalled reinforced PVC hose (as
flexible as you can find) that won’t
kink or crush when it’s stepped on
is a better choice. Be sure the
pump is wired correctly — hot
wire is brown, ground lead is
black. Wiring must be secured
with cable ties and connections
should be made well above the
water level in the bilge. Short
leads from the pump often make
this impossible and you’ll need to
use adhesive-lined heat-shrink
terminals. (See DIY 1998 #4 for
complete crimping instructions.)
Consider using these anyway to
ensure connections are impervious
to water sloshing about in the
bilge.
When choosing a pump, keep
in mind how far the pump must
push the water upwards before it
goes over the side. Remember that
nominal flow rates are based on
zero lift or a zero head discharge
rate. Installation factors — the type
of hose and number of bends, how
far the pump must push the water,
the height of the thru-hull fitting —
all affect flow rates. A fair lift is
often required. This consideration
is critical when you’re deciding
where to put the discharge fitting
of any bilge pump so water won’t
drain back into the boat under any
Corrugated hose typically sold for
bilge-pump use is cheap,
but the corrugations slow down the
discharge rate and heavy
tools or a carelessly placed foot will
crush it.
circumstances. Water reversal is a
common problem in many boats
that immerse the above-thewaterline thru-hull; the thru-hull is
covered underway, causing a back
siphon, and the bilge floods with
water when the pump shuts off. To
prevent backflowing, loop the
discharge hose high above the
waterline; don’t use a one-way
check valve which can trap crud
and restrict flow. Unfortunately,
either solution reduces a pump’s
discharge capacity and they are
only effective where the thru-hull is
- Ti p A BAD FIT
Double-clamped hose
connections are best but
sometimes the fitting on the
pump is not long enough to
fit completely under the backup (outer) clamp. When this
happens, don’t tighten the
clamp so much that it
partially collapses the hose.
© DIY boat owner 2001 1-888-658-2628
10
PLUMBING 101
installed a minimum of 20cm (8”)
above the waterline. On sailboats,
the measurement is taken when the
boat is heeled; installation is
usually only possible when the
discharge hose exits at the transom
near the centerline. Where the
thru-hull is mounted closer to the
waterline you need to provide an
anti-siphoning valve at the top of
the loop or an air vent. This can be
accomplished by teeing into a
cockpit drain or into a shower
discharge. All tees must be high
above the waterline.
Various automatic switches are
available, from simple tilting floats
that usually contain a switch
triggered by liquid mercury (these
can jam and foul) to air-pressure
types (more reliable) and even
sonic and electronic sensors
(definitely more expensive; maybe
more reliable).
Regardless of the
sophistication of an electric pump
system or even an engine-driven
pump, power can fail and every
boat should have at least one high-
Every boat should have at least one
high-capacity manual bilge pump as a
backup.
capacity manual bilge pump as a
backup. (And, a large bucket! It’s
said that there is no manual bilge
pump better than a frightened
boater with a bucket and this is
probably true but, at that stage,
you are probably better off
sending out a Mayday call on the
VHF while pumping with the other
hand!) These are positive
displacement diaphragm pumps.
Diaphragm pumps are rugged,
can pass some debris and solids
and are available in a variety of
sizes. They can be installed
internally with a deck plate or in
the open on a bulkhead. Units are
available from Henderson, Edson,
Rule, Vetus and Whale.
If you own a small boat don’t
skimp on the pump size.Remember
that given the same 2.54cm (1”)
hole in a hull, a small boat will fill
and sink a lot faster than a large
one. When fighting a leak, you
need all the time you can get.
Maintenance
Bilge pumps don’t need much
maintenance. Simply keep the float
switches and the bilge clean and
free of debris and oil which can
damage the rubber parts in most
pumps. (Remember that
submersible units generally have to
be replaced when they fail, with
the exception of the higher-end
Lovett pump — all of whose
components, be it a set of belts,
switch or motor, are fully
replaceable in the event of a
failure.
And that brings us to the
ultimate bilge pump: the wet or dry
vacuum (Shop Vac). Granted, it
only runs on shorepower, but it’s
the only pump that will get every
last drop of water out of your
bilge. Try it sometime! In our
Thunderbird sailboat fleet it is
considered essential equipment. In
Lovett bilge pumps
are the only submersible
units that are UL approved
and have replaceable parts.
an emergency situation,a valuable
alternative to a bilge pump is to
use the intake hose of the engine
cooling water pump. Debris in the
bilge can plug the engine, so you’ll
need to attach a strainer (screen) to
the hose end.
SCUPPER
PLUMBING
Power- or sailboats with large
open cockpits often come from the
factory with woefully underengineered scupper drains.
Consider this worst-case scenario:
a disabled or slow-moving boat in
a following sea suddenly pooped
and swamped by a big breaking
wave. Would your boat survive
this? Lots of big scuppers in the
cockpit are a good thing. If
possible, have them drain above
the heeled waterline or you must
install seacocks. If your cockpit is
so deep that it is close to or below
the waterline, any drains will have
to go to seacocks installed in the
bottom of the hull.
Sailboats with deep teeshaped cockpits have particular
problems because when they heel
the scuppers are just as likely to
pump water in as let it out. Oneway flapper valves can help.
Often the hoses are crossed from
one side to the other so that the
© DIY boat owner 2001 1-888-658-2628
11
PLUMBING 101
port drain goes to the starboard
thru-hull or vice versa. This keeps
the low-side thru-hull connected to
the high-side drain and everything
stays dry. This style of hose
arrangement can be a liability
during winter storage in northern
climates, however, as it’s difficult
to avoid low spots that trap water
in the hose. This water may freeze
and block the scuppers or, worse,
pop the hose off the drain fitting
allowing the boat to fill up with
water over the winter. (A good
leak-free tarp is recommended.)
Powerboats have their own
scupper problems. For example,
there is a scupper system on a
deep-V sportboat built by a
reputable manufacturer that is
supposed to drain the cockpit and
engine hatches to a series of
shallow aluminum channels. These
channels lead to a thru-hull and
flapper valve an inch or two
above the at-rest waterline on both
sides. If a twig, leaf or other small
debris were to lodge in the oneway valve, forcing it to open, and
if two people stood to one side of
the cockpit, water would happily
flow back into the boat and into
the engine compartment. Yes, the
boat will sink at the dock once the
bilge pump quits. I’ve seen it
happen. This type of scupper
system needs serious reworking.
Maintenance
Scupper hoses should be of the
same high quality as others below
the waterline and should be
replaced if they become cracked
or degraded. Follow the same
maintenance procedure for
seacocks or valves below the
waterline as you would for those
above.
Nick Bailey has been in the marine
service profession for more than 20
years and currently is service manager
of Bristol Marine in Mississauga, Ont.
He and his wife own and race a
wooden Thunderbird that recently
underwent a major refit. Watch for an
article detailing some of their renovations
in our next issue.
© DIY boat owner 2001 1-888-658-2628
12
PLUMBING 101
Adding a Water Heater
before use are usually fired by
propane, are less common on
boats and are beyond the scope of
a do-it-yourself article. Work with
explosive propane and the
handling of combustible gases
should be left to a licensed gas
fitter.
In a similar vein, if you are not
familiar with the basic 110-volt
wiring required to hook up your
hot-water heating element, you
should seek the assistance of
someone who is experienced. At
the very least, have your
connections checked prior to
plugging in the heater.
When planning the layout of
the system, especially the tank
location, try to arrange a close
look at the same model boat
already equipped with a factoryinstalled system — and copy it
where that’s practical. Or you can
contact the builder (if they’re still in
business) for guidelines. A
professional-looking “stock”
installation will always raise the
resale value of your boat. You do,
however, have the freedom to
AVOID
THIS
TABBING
STRINGER
AVOID
THIS
OK
If you live and cook aboard for
longer that the occasional
weekend cruise, hot running water
is more than a convenience. The
good news is that if your boat has
a 110-volt shorepower system and
cold water, you’re already halfway
to a hot-water system.
There are two completely
different approaches to the
problem: a storage-tank heater or
a flow-through “demand” heater.
The former is the most common
type of system. It has a storage
tank very similar to a household
unit but with a smaller capacity.
Heat is usually provided at
dockside by a 1,500-watt 110-volt
AC heating element and, while
underway, by hot engine coolant
recirculating through a heat
exchanger in the tank. Units are
available from Atlantic Marine,
Raritan, Seaward and others.
Never install a household water
heater which is not ignition
protected and could spark and
cause a fire.
Demand heaters that do not
store water but heat it immediately
install more deluxe fixtures should
your budget allow it.
The tank will need to sit on a
level surface so a solid 19mm
(3/4”) plywood epoxy-painted
shelf will need to be prepared
and screwed or fiberglass tabbed
into place (see Figure 8). Once
the tank is shoehorned into place
(usually a tight fit in a cockpit
locker or in the engine room) and
fastened securely, run your cold
water (in) and hot water (out) lines
with hose. For the “hot” side,
good quality clear-braid PVC
hose is pressure-rated at 65°C
(150°F) and connects the
traditional way with adapters and
double clamped. (Make sure the
Figure 8
Before cutting or drilling anything
when running piping, check on each
side of the bulkhead or partition to
ensure you don’t cut into structural
stringers or tabbing that hold the
bulkhead in place.
© DIY boat owner 2001 1-888-658-2628
13
WATER HEATER
Equipment list:
Description
Cost
6-gallon (typically) hot-water tank (may not
include engine coolant heat exchanger and a
place to put it!)
15-amp breaker
$350-$600
$25
14-gauge multi-strand boat cable
$1.37 per foot
Replacement mixer for galley (or additional
single faucet)
$20-$100
Mixer for vanity (plus optional shower) and
shower sump and pump
$20-$100
Hose or pipe sufficient to go from heater to galley
and vanity
$10-$100
Tee for cold-water line, miscellaneous fitting
connectors, elbows, clamps
$20-$100
clamps are tight, but not so tight
they cut into the hose. If you see
particles of hose squishing through
the cracks in the clamp, you’ve
destroyed the hose.) An even
better choice is semi-flexible
plastic pipe, which is more
durable, less prone to kinks and
usually has fittings that are less
likely to leak and easier to
assemble.
Threading piping through the
boat is time-consuming and fiddly
work. Access is often difficult and
you will probably have to drill
many holes through bulkheads. Be
very careful! Before cutting or
drilling anything, check on each
side of the bulkhead or partition to
ensure you don’t cut into a tank,
wiring or other piping, or structural
stringers or tabbing that hold the
bulkhead in place (Figure 8) .
Fasten the plumbing every few feet
with cable clamps or wire ties and
try to keep it out of the bilge to
prevent contamination. Avoid tight
bends that can kink hose; instead,
install a 90° elbow. The tee
connection to the cold-water
system can be made anywhere
downstream of the pressure pump
and before the first fixture. Hot
water heaters need a check valve,
either at the water inlet to the tank
or at the tee connection so the hot
water cannot flow back into the
cold water. Make sure you have
one. You may have to remove the
sink to get access for your
connections to the mixer or faucet.
Provide for easy access to the
tank, fittings and all connections
for maintenance.
Any 110-volt wire used should
be at least 14-gauge copper multistrand boat cable and must be
sized to the amperage and
wattage of the heater; depending
on the routing, you may need 12
or 10 gauge. Household singlestrand cable is not safe in a boat
because engine vibration and
jarring from when the boat slams
into waves fatigues the wire,
leading to breaks and shorts and
fires. The hot (black) wire connects
to one terminal of the element and
the neutral (white) wire connects to
the other. Ground the tank via the
green or bare copper wire.
Assuming you have a 110-volt
system — a breaker panel and
hull inlet with circuit protection that
was installed to nationallyrecognized codes (NFPA) —
connect the white to the common
neutral buss and install the breaker
into an empty slot in the panel
connecting the hot (black) lead to
the breaker and the breaker’s
other pole to the hot distribution
buss. Never directly connect a
water heater to a power cord
plugged into an outlet on shore.
Don’t do any wiring until you have
unplugged and stowed your
shorepower cord — a wellmeaning soul just might plug it
back in again at an awkward
moment. Keep all 110-volt A/C
wiring physically separate from
your DC wiring. Make sure no
neutral (white) wires connect to
any ground within the boat — this
is critical — and make sure your
shorepower cord and main AC
supply is properly grounded
through the dockside power
system. Now turn on the pump, fill
the tank and turn on the power in
that order to avoid heater element
meltdown. Check for leaks. There
will be a few. (Contrary to popular
opinion, AC electrical service does
not cause stray current corrosion;
this is a DC problem, either within
the boat circuit or through the AC
grounding wire. If you’re
concerned about stray current
corrosion, install a galvanic
isolator or isolation transformer.)
Next, hook up your engine
hot-water heat exchanger —
consult a mechanic or your local
engine representative first. Some
raw-water-cooled engines (early
Yanmars for example) won’t put
out a steady supply of hot water;
the temperature alternates
between hot and cold as the
thermostat opens and closes.
Others, such as Atomic 4s, need a
separate recirculating pump to
help move the engine coolant
through the heat exchanger.
© DIY boat owner 2001 1-888-658-2628
14
PLUMBING 101
for
heads
Add a stock of latex
rubber gloves to your
tool kit and read on
because it’s possible to
solve most marine
sanitation problems with
repairs and upgrades.
Fear and Loathing in the Vanity
By Nick Bailey
In the last issue (1997-#1) we
covered all plumbing systems other
than the head, otherwise known as
the marine toilet or as commonly
referred to as a marine sanitation
device (MSD).
Of all of the onboard plumbing
systems, the head has a redundant
reputation as a real troublemaker.
This notoriety is exaggerated,
although not entirely undeserved.
MSDs are seldom well-maintained
and even less well-understood.
Beware, neglect will lead to nasty
surprises. If you thought the device
was a bit disgusting even when it
was working well, then just wait
until it screws up!
HEADS: The Front
End of the Sanitation
System
There are basically four kinds of
marine toilets, classified by how the
sewage is moved: manual pump,
electric pump, vacuum and gravity.
The manual-pump toilet is the
most common type. Well-known
examples are made by Blake,
Groco, PAR (made by Jabsco),
Raritan and Wilcox Crittendon.
Flush water is pumped in at the
same time the sewage is pumped
out, usually by a double-acting
manual pump. The down stroke of
the pump handle forces a piston
down, pushing sewage out of the
pump chamber through a one-way
valve to the holding tank (or
overboard to a thru-hull) while at
the same time drawing in seawater
for flushing from a thru-hull into the
upper half of the pump chamber.
On the upstroke, the one-way
inlet valve is pushed closed and the
flush water is forced out along the
toilet’s rim. As the piston rises,
sewage and used flush water are
drawn into the pump chamber
ready for the down stroke that
again forces everything out the
discharge hose. The head inlet
valve usually has a small manual
control labeled “Flush or Dry Bowl”
so that you can control the amount
of flush water — a bare minimum if
you want to preserve your holding
tank capacity, or lots of flush water
if you want to purge the discharge
hoses before leaving the boat at the
end of the weekend. Regardless,
the pumping and flushing
procedure should end with the
valve closed to leave a relatively
dry bowl.
These traditional heads range
widely in price from about $200 to
more than $1,000 and vary in
complexity. Most have a multitude
of seals, gaskets, O-rings and valve
surfaces that can foul, stick, clog,
jam, wear out and otherwise cause
aggravation. Most heads have
complete rebuild kits available. The
ability to field-strip, clean and
rebuild a head is considered an
essential life skill for any serious
long-distance cruiser.
A unique alternative to the
conventional manual head is the
LaVac head by Blake. This
remarkably simple head does away
with the complicated pump
assembly at the head itself and uses
a pump similar to a diaphragm
bilge pump but installed on the
discharge hose from the head. The
most unusual feature is the toilet
bowl lid that forms an airtight seal
on the bowl itself. When the bowl
contents are pumped out, the
suction draws seawater for flushing
into the head via the usual inlet
seacock and hose straight to the rim
of the bowl. To pump dry, simply
open the lid, which breaks the
suction. This head has far fewer
moving parts than others, which
means less maintenance and
trouble. However, large people are
advised not to flush while seated on
this head!
The electric toilet may simply be
a powered version of the manual
toilet with a hefty DC motor driving
a reciprocating crank, which in turn
© DIY boat owner 2001 1-888-658-2628
15
RX for HEADS
actuates the same basic pump
mechanism described above.
Alternatively, it may have a
macerator pump.
The macerator-pump toilet is
quite different in that it uses a
rubber impeller pump to pull in
flush water and, usually driven on
the same shaft, a centrifugal or
impeller discharge pump with a
chopper or macerator blade (not
unlike a garbage disposal unit) that
purees the sewage so that it won’t
choke the pump. These heads have
the convenience of push-button
flushing, but because the rubber
pump impeller will disintegrate if
it’s run dry, you don’t have the
option of controlling the amount of
water used, which can be at least
7.5L (2 gal) per flush. This type of
head could prove impractical if
connected to a small holding tank
system. PAR and Raritan make the
most common macerator units.
Popular on larger powerboats,
the Vacu-Flush head by Sealand
(formerly Mansfield) is unique in the
marketplace. It uses a vacuum
pump — a powerful bellows pump
with extra one-way “duck-bill”
valves — in line with a vacuum
accumulator tank that draws flush
water from the potable water
system. The vacuum system
behaves like a pressure water
system in reverse. When the “flush”
foot pedal is pushed, a small
amount of water is let into the bowl,
the discharge valve in the toilet
opens and the sewage promptly
disappears with a “whoosh” down
the discharge hose towards the
vacuum tank. Simultaneously,
somewhere down in the vessel’s
machinery spaces, an automatic
pressure switch senses the sudden
change in vacuum and engages
the vacuum pump. The pump chugs
away until it reaches full pressure
then the pressure switch shuts it
down. In the
GATE-FREE
meantime, it has
scavenged the
If your boat has gate valves, replace them
sewage from the
before they seize or break. Many seized gate
vacuum side of
valves are irrevocably seized to the thru-hull;
the system and
be prepared to remove and replace the whole
delivered it down
thru-hull. To do this, sever the thru-hull stem and
to the nonfree the valve with a mini-grinder or hacksaw.
vacuum holding
If the thru-hull nut is also seized, grind off the
tank (or wastemushroom head on the outside of the hull,
treatment system
knocking the remnants through to the inside. Be
or overboard).
careful not to gouge the hull.
This is a nice
system. It has
the U.S. Coast Guard (USCG) calls
relatively low power consumption
a Type III MSD. In these areas, it’s
and it uses less flush water than any
not legal to pump any sewage
other. It is, however, costly to install,
overboard even if you have a
and although more reliable and less treatment system on board. In most
finicky than any other electric and
U.S. coastal waters (inside the
most manual head systems, if things
three-mile limit), it’s legal to
do go wrong, it can be expensive
discharge sewage only after it’s
to fix. Vacuum leaks are particularly
treated by a USGC-certified Type I
sneaky things to track.
MSD (i.e. Raritan Lectra/San,
The last category of heads is
Sealand SanX and others), or Type
gravity powered. In these systems
II MSD for boats over 9.8m (66’).
the sewage drops straight into the
These costly units (about US$2,000
storage tank below. The most
complete with the head) are small
common variety is the portable-style
on-board sewage treatment plants
(commonly referred to as portathat macerate and disinfect the
potties), which stores the waste in a
sewage until it meets very specific
small, removable tank section of the
bacteria counts and standards for
head. Some models have deck
turbidity (suspended solids) prior to
pump out fittings (mandatory in
discharge.
Canada), some have recirculating
flush capability in which the
DISPOSAL: The Back
sewage in the tank mixed with
End of the System
deodorizing additives gets pumped
around for flushing. Some have a
Discharge Hose
fairly large capacity and provision
for pressure-water flushing.
Much has been written by various
Unfortunately, some have a bad
authorities on head hose. The
reputation as cheap, flimsy, prone
consensus is that if you install the
to leakage, smelly and generally
wrong kind of discharge hose it can
obnoxious. Many boaters prefer to
be a major contributor to head
use a bucket (which may or may
odor. Head hose should be flexible
not be legal in your jurisdiction)
and smooth-walled, preferably
rather than carry around sewage in
heavy-gauge PVC sanitation-grade
such a dubious container.
hose or top-quality reinforced
If your boat operates in waters
neoprene. The spiral-ribbed thin
designated as “No Discharge
wall hose often used is okay for
Zones” it must be fitted with what
bilge pumps but is too thin for an
- Ti p -
© DIY boat owner 2001 1-888-658-2628
16
RX for Heads
Head Rebuild
A rebuild kit includes replacement
parts for all the perishable items and
a parts list helps you identify other
problem areas.
1
Preparation Pump out the
holding tank and flush the
system well. Shut off any
seacocks, disconnect discharge
and intake lines, unscrew the
mount bolts and remove the
head from the boat in order to
work on it in less cramped
quarters (or remove the pump
assembly only). Remove pump
assembly from base. Open the
head repair kit and carefully
check the parts and the
enlarged diagram provided.
2
Inlet Valves Remove the
valve cover (typically six
screws) and remove the flapper
valve. Clean all mating surfaces
carefully, replace all valve parts
with new ones and replace any
O-rings and seals on the inlet
valve lever. Lightly smear
sealing surfaces with silicone
sealant.
odor-free head hose and the ribs
trap sewage. Rigid Schedule 80
PVC pipe or household ABS (DWV
service) offer a non-permeable
alternative and are useful if you
want to eliminate any low spots
that tend to hold sewage. Be
3
Piston Rings and Shaft
Seal Wrap the piston rod
and carefully secure with vise
grips. Unscrew the pump
handle and release the piston to
drop or knock out the bottom of
the pump housing. Clean and
lubricate the pump cylinder.
Replace the piston rings or
piston assembly, and remove
and replace the piston rod seal.
With an external seal, unscrew
or remove the retaining ring; an
internal rod seal must be pried
out from the inside.
4
Discharge Valves
Remove, clean sealing
surfaces and replace the flapper
valve at the pump base.
Dismantle the discharge elbow,
clean out and replace the duck
bill or “joker” valve.
5
Seals Replace any sealing
gaskets and O-rings, clean
all mating surfaces and check
carefully for cracks in all
housings.
6
Assembly Reassemble care
fully. Don’t over-torque the
plastic housings, which crack
very easily. If cracked, they must
be replaced.
7
Clean up Reinstall, hook
up, open the seacocks and
test for leaks.
careful not to use light-gauge
Schedule 40 pipe — it can crack,
especially when very cold. When
shopping for hose, the standard
head discharge size is 1-1/2”
inside diameter (ID) hose; some
macerator-type heads will
discharge via a 1” ID. Inlet suction
hose is usually 3/4” ID and should
be firm and non-collapsible.
Vented Loops
Regardless of how well or poorly a
marine sanitation system goes
about its business, there is one thing
it must never do and that is sink the
boat. This happens more often than
you might suspect simply because
most heads in sailboats and some
in powerboats are installed below
the waterline and connected to a
seawater inlet. Seawater siphoning
into the head bowl results when one
of the flapper valves on the head
(“Flush or Dry Bowl”) fails.
Sailboats spend a lot of time
heeled over at angles up to 30° or
more, which radically changes
what fittings are below the “heeled”
waterline. One solution is to always
turn off the head inlet seacock when
it’s not in use, but this may not be
practical if the seacock is
inaccessible. Some boats even
come equipped with a secondary
(accessible) shut-off valve on the
intake line. These security measures
all depend on the operator to do
the right thing, but to err is human.
Besides, there are always guests
and children and they might not
always remember or understand
instructions.
The proper head installation
will incorporate an automatic
method of disrupting any siphoning
action. To accomplish this,
configure the inlet hose with a tall
loop above the waterline and close
to the underside of the deck
between the head pump and the
bowl. This may require the removal
and replacement of the standard
hose fitted on the toilet. At the top
of the loop, install a special Ushaped fitting known as a vented
loop or anti-siphon vent. The vented
loop incorporates a small one-way
© DIY boat owner 2001 1-888-658-2628
17
RX for HEADS
Thru-hulls
The head inlet and discharge thruhulls should have reliable, quickacting valves. Seacocks with
integral quarter-turn valves or thruhulls combined with a ball valve of
stainless steel, bronze or Marelon
are much preferred over gate
valves.
polyethylene, available in shapes to
fit most locations. If made of linear
(not crosslinked) heavy-gauge 6mm
to 9mm (1/4” to 3/8”) seamless
polyethylene, they will give
excellent service. Lighter gauge
tanks are flimsy and prone to odor
penetration. Heavy-gauge (2mm
(3/32”) or thicker) stainless-steel
tanks are strongest and the least
odor permeable. However, in the
long-term (five-plus years) such tanks
corrode from sewage acids.
Corrosion attacks the seams first,
leading to leakage and the need to
remove and repair them. (Aluminum
and other metals are unsuitable
holding tank materials because they
are less corrosion-resistant than
stainless steel.)
Bladders or flexible-rubber
tanks are sometimes used. They are
difficult to secure and, as a result,
they are subject to chafe,
particularly in a sailboat. Flexible
tanks are also tough on the fittings
connected to them. These tanks
must be inspected requently, so
should be installed in an easy-toaccess spot. Also, some head
chemicals may “devour” the rubber,
creating a repulsive smell more
intense than any known head odor.
Remember, sewage weighs
3.6kg per 3.8L (8lb per gal), which
is a lot of mass sloshing about.
When choosing a tank it makes
sense to spend the extra money for
a good one.
Add a Holding Tank
If you need to fit a tank, decide
first what size you need. Do you
use the boat for day trips,
weekends, or extended cruises?
The minimum average flush
volume per person per day is
about 11.3L (3 gal). Therefore, a
couple on a weekend cruise will
need a tank capacity of 45L (12
gal). For two couples, 91L (24
gal) is the minimum. The other
consideration is how big a tank
you can fit into the boat. Stock
polyethylene tanks are available
in many shapes and sizes and
custom stainless-steel tanks can be
built to suit your available space.
(Refer to Figures 1, 2 and 3 for
typical holding tank installations.)
It’s also possible to build a
DECK PUMPOUT
FITTING
Holding Tanks
Many boating areas in North
America, in particular most
freshwater lakes and rivers, don’t
allow marine sanitation systems to
discharge any sewage overboard
whether it’s treated or not. The boat
must be without an installed toilet
on board or the head must have a
holding tank.
Holding tanks come in all
types. On boats built for saltwater
markets, the holding tank may be
an afterthought, either too small,
inaccessible for maintenance or
generally substandard. The most
common tanks are molded
VENT LINE
HOLDING
TANK
INTAKE
THROUGH HULL
DIP
TUBE
P-TRAP
Figure 1
“No discharge” deck pumpout only.
© DIY boat owner 2001 1-888-658-2628
AMERICAN BOAT & YACHT COUNCIL
air valve that opens if any suction is
present in the hose, allowing air to
enter the line and break the
siphoning action. A similar siphon
break is required on the discharge
hose if it’s connected to a thru-hull.
There are a few problems with
vented loops. The anti-siphon vent
fitting can clog with debris, calcium
or salt crystals and quit working. To
prevent this, clean periodically. As
well, sewage odors in the
discharge line vent sometimes filter
into the boat. To eliminate this,
attach a small diameter hose to the
nipple on top of the vented loop
and lead it to an overboard vent
fitting mounted well above the
waterline or connect it to an
existing holding tank vent.
Alternatively, feed the hose into a
cockpit scupper provided that it’s
above the waterline at all times.
18
RX for HEADS
DECK PUMPOUT
FITTING
VENT LINE
SIPHON
BREAK
"Y" VALVE
VENT LINE
HOLDING
TANK
INTAKE
THROUGH
HULL
OVERBOARD
DISCHARGE
PUMP
DISCHARGE
THROUGH-HULL
Figure 2
Overboard discharge option after the holding tank.
fiberglass or wood-epoxy tank or
glass in an existing seat locker
and convert it into a tank. In order
to resist stress cracking and avoid
pinhole leaks, it should be heavily
built and thoroughly epoxy-barrier
coated on the inside to prevent
moisture penetration. (See
page 27 for instructions
on building a wood-epoxy tank.)
Any installed tank must be
strong enough to carry the full
sewage load and it must be
securely blocked or clamped in
place. Any movement or flex puts
stress on the inlet, discharge and
vent connections and either cracks
the tank at the fitting or the fitting
itself cracks. When space is tight,
convert your water tank to a
sewage holding tank and then
squeeze a bladder tank into some
nook and use it for water. At least if
the bladder tank leaks you won’t be
subjected to a horrifying stench.
If your existing water tank is
polyethylene with the usual 1-1/2”
fill fitting and 1/2” vent and outlets,
you will have some difficulty
replacing the 1/2” outlet with a 11/2” pumpout discharge fitting. If
the tank is heavily reinforced, the
water outlet can be enlarged with a
holesaw to accept a 1- 1/2” hose
barb mushroom-style thru-hull
(preferably reinforced plastic) with
backing nut. Caulk the thru-hull well
with a polyurethane sealant (3M
5200, Sikaflex or other). This
modification has been done
successfully but because
polyethylene does not bond well to
most sealants, the seal may fail. I
recommend replacing the tank with
another the same size but equipped
with the correct fittings.
All hose connections should be
double-clamped with stainless-steel
clamps, and any head installations
below the waterline should have
vented loops on the intake and
discharge lines. To prevent noxious
odors emitting from a vented loop,
attach a hose from the valve to an
overboard vent mounted above the
waterline (Figure 4) or tie it into
DECK PUMPOUT FITTING
HEELED
WATERLINE
VENT LINE
SIPHONE
BREAK
WATERLINE
INTAKE
THROUGH-HULL
HOLDING
TANK
TYPE
1
"Y" VALVE
DISCHARGE
THROUGH-HULL
Figure 3
Overboard discharge option before the holding tank.
Figure 4
To prevent water from siphoning back
into the head, install a vented loop in
the inlet hose (and the discharge hose
if connected to a thru-hull) located
above the maximum-heeled waterline.
© DIY boat owner 2001 1-888-658-2628
19
RX for HEADS
the holding tank vent or cockpit
scupper. It’s also worthwhile
installing the largest practical vent
diameter or two vents on the tank to
assist with the oxygenation of the
sewage (see “Odor Control”
below). Note: On boats with
optional overboard discharge, the
Y-valve must be secured with a
padlock, cable tie or the valve
handle removed when operating
within the three-mile limit.
Odor Control
There are several sources of head
odor of which leaks are the worst
cause — find them and fix them.
Discharge hoses, even top-quality
ones, eventually become saturated
and odor penetrates the walls. To
check your head hose for odor
permeability, try the rag test. Wipe
the outer surface of the hose with a
damp cloth. If the cloth smells, the
hose is permeable. Replace
immediately. To eliminate hose
odor, avoid sewage remaining in
the line for long periods. Flush well
or even revise your hose routing to
minimize low spots or traps.
Consider replacing hoses with
straight-through plastic pipe but
keep in mind that the proper size
head-to-pipe or hose-to-pipe
adapters may be hard to find.
The inlet hose can be another
cause of odor, particularly in
saltwater. Marine growth
decomposing in the stagnant water
of an intake line can mean the first
flush of the weekend will reek. A
strainer on the inlet line can help
solve this. Periodic purging of the
entire inlet line with a 30% solution
of vinegar and fresh water will also
help. Never use bleach or other
commercial cleaners in a marine
toilet; it can attack the rubber and
metal parts.
Low-cost in-line head chemical
dispensers, such as the Head-O-
Figure 5
The Head-O-Matic Tank-ette installs
in the intake line and auto-feeds head
chemicals to treat water pumped to
the head.
Matic Tank-ette (Figure 5), treat all
water pumped to the head to
eliminate intake odor. Easy to
install, the Tank-ette (CDN$59.95/
US$39.95) clamps onto a 3/4”
intake line (use adapters for other
hose sizes) mounted above the
waterline. A bullet of blue solid
chemical drops into the unit and is
replaced after one month or when
the water runs clear. Replacement
bullets cost $9 or less. An optional
E-Z Flush cap facilitates winterizing
or flushing of the head.
The discharge joker valve can
leak allowing sewage to back up
into the head. Or if the piston rings
are worn, sewage can leak past
into the flush-water side,
contaminating it. Then it’s time for
head repairs. Another source of
odor is generally head area
cleanliness and, although
unpopular (and probably
unenforceable), a “guys sit to pee”
rule will reduce splash, odor and
cleaning.
Cheap, lightweight,
polyethylene tanks are odor
permeable; heavy-gauge tanks are
much less so but odors may
eventually seep through. Septic-tank
sewage odor is a by-product of the
anaerobic bacteria that thrive in the
oxygen-deprived, carbon-dioxide-
rich environment of most holding
tanks. This is why municipal
sewage treatment plants aerate
sewage to promote the growth of
aerobic oxygen-loving bacteria,
which give off much less odor as
they naturally break down the
sewage. The same is true of
backyard composters.
Peggie Hall of Peal Products, a
company specializing in marine
sanitation systems in Atlanta,
Georgia, advocates a simple,
innovative approach to naturally
eliminate sewage smells in the tank.
The key is to fit the largest practical
cross-flow vent system to the tank —
usually two independent vent lines
of 2.54m (1”) diameter hose to
each side of the boat (Figure 6).
This sets up true cross-flow
ventilation of the tank, clears out the
carbon dioxide and prevents
oxygen starvation, which allows the
aerobic bacteria to gain the upper
hand over the smelly anaerobic
types while breaking down the
sewage by natural fermentation.
Although it might seem counterintuitive, this enlarged vent system is
reported to eliminate most holding
tank odors. For the idea to work,
the vent hoses must be as short as
possible and free of low spots that
can trap air. It’s also important that
the hoses aren’t restricted by filters
or tiny screened fittings on the
outboard end. With sailboat
installations, care must be taken
that the vents come straight up from
the tank top to avoid filling while
the boat is heeled. They should exit
at locations above the waterline at
all times (i.e. the bow or the
transom). According to Hall, the
rule is: The less fresh air a holding
tank gets, the more it will stink.
Vent maintenance is also
important in odor control. Vent lines
are easily blocked by spider webs
or by sewage if the tank has been
© DIY boat owner 2001 1-888-658-2628
20
RX for HEADS
More Routine
Maintenance
Maintenance Rule #1 is to make
sure that everyone who uses the
head understands that it’s not
connected to the town drain and
that it is by nature a finicky,
cantankerous, spiteful device. All
instructions must be strictly obeyed,
such as “Don’t put anything in the
- Ti p - DRIP PAN
A plastic pan or cutoff jug bottom placed
underneath the lowest point in
the system will prevent any
unpleasant extract from
spilling into the bilge when
you drain it for maintenance.
head unless you have eaten it first.”
It’s claimed that the legendary
Wilcox Crittenden Skipper head
can flush an overcoat, but for the
rest the only exception to the “eat
first” rule is marine or ultra-cheap
one-ply toilet paper.
If Rule #1 is followed, heads
don’t need much maintenance.
Check that the vents are clear — be
aware of any sudden resistance in
Anne-Marie Hendry
overfilled and “ram fed” by the
head pump — especially if the
outside hull vent fitting is tiny and
screened. This can lead to a
dangerous situation since the
fermenting sewage produces gases
and pressure builds. It doesn’t help
if your guests stand on the pump
handle to pump the head due to the
back pressure. I have seen heavygauge rectangular polyethylene
tanks blow up like balloons and
break the joinery meant to contain
them. There’s also the urban legend
of the couple in fancy dress whites
taking their friends by boat to the
Commodore’s Ball. They realize
they need a last minute pump out,
blissfully unaware that a 6m (20’)
geyser of raw sewage would erupt
when the deck fitting was opened.
The opposite happens when
the vent is clogged during a pump
out. The large diaphragm pumps
will easily suck a heavy stainlesssteel tank flat into a crumpled
pancake. So check the vents
periodically for blockages and
spider webs. A ruptured holding
tank is the smelliest one of all.
Figure 6
Eliminate most holding tank odors
caused by oxygen-starved bacteria by
fitting the largest practical cross-flow
vent system to the tank.
pumping effort and never force the
pump. Experts recommend
occasionally flushing half a toilet
bowl of warm water with
biodegradable laundry detergent
through the system followed by two
ounces of mineral or baby oil (not
vegetable oil, which slimes up the
lines and tank). Periodic greasing
of the piston rod is also
recommended. The oil will help the
head and the detergent will
emulsify the oil in the tank to
preserve good bacteria. If the boat
is equipped with a Type I or Type II
MSD, do not flush cleaner or
treatment into the system unless it
was specifically designed and sold
for that purpose.
Many pros recommend a
complete head rebuild every two
years as the best preventative
maintenance program. (Add this
task to your spring recommissioning
list.) This ensures the head is always
in top shape and it also guarantees
that you will be familiar with the
- Ti p - HEAD
FILL-IN
What do you do when the head is
not working? Carry a supply of FlushMe-Nots. Line the head bowl (or a
bucket or whatever else fits) with the
plastic bag then add some high-tech
powdered absorbent (it’s part of the
package). After use, seal the bag
with a twist-tie and dispose of it as
you would a diaper. (Contact: F.C.P.
Products, Box 229, Billerica, MA
01821; Tel: (508) 783-2500.)
unit when repairs are needed.
In saltwater, calcium can build
up in the toilet and lines and almost
becomes like a hard coral growth
due possibly to microscopic
diatoms. Periodic flushing with
vinegar will help dissolve these
deposits, but if they are severe and
the head becomes difficult to pump,
you may have to replace the hoses
or carefully flush the system at least
once with diluted hydrochloric acid
(muriatic acid). This must be done
carefully as the acid can slowly
attack metal parts in the head
system.
Regularly check all hose
connections for new signs of
leakage. To check the operation of
the anti-siphon valve, blow through
a piece of hose fitted over the
nipple.
Simple maintenance habits
also help to minimize odor; the
last flush of the cruise, especially
at the end of the weekend, should
always be a thorough one to
eliminate sewage standing in the
discharge line.
Nick Bailey has been in the marine
service profession for more than 20
years and currently is service
manager of Bristol Marine in
Mississauga, Ont. He and his wife
own and race a wooden
Thunderbird on Lake Ontario.
© DIY boat owner 2001 1-888-658-2628
21
RX for HEADS
Pump works freely but
head won’t draw in
flushwater
Check
intake
seacock
is open
CLOSED
Head
leaks
Carefully
tighten
Pump works freely but
bowl fills faster than it
drains
OPEN
Open and try
again
Pump
harder
Check level in
holding tank
NO
Temporary sticking
one-way discharge valve
NOT FULL
Pump piston
rings not
sealing or
piston broken
NO
Check overboard discharge
seacock for calcium build-up
Pump doesn’t
work freely
OKAY
REBUILD
HEAD
Still leaks
OKAY
FULL
Remove hose and
check for blockage or
loss of prime
Check and
clear vent
Discharge
valve may be
clogged
NO
YES
Treat with
acid
Check inlet
valve is open
YES
Pumpout tank and check vents are clear
Bowl fills back up
when unattended
Inlet or
discharge valve
leaking
Pump and close
seacocks one at a
time
If sewage, clear or
replace discharge
valve
© DIY boat owner 2001 1-888-658-2628
22
TANKS
MADE-TO-MEASURE
TANKS
for 12 years without any bad
tastes or odors. The tanks
were constructed with West
System brand epoxy, but
I’m sure other resins
would net similar
results.
Carefully
measure the
space for
the tank,
then make a
cardboard
template. Assemble the
pieces using masking tape to
hold
it all together. Dry-fit the
Figure 1
template, then trace the patterns
A tank constructed of plywood and
onto the plywood. Building a
“waterproofed” with
rectangular tank is
multiple coats of epoxy resin. Baffles
straightforward: cut the ends,
prevent the contents from surging in
sides, bottom, top and baffles out
the tank and scallop-shaped cutouts in
the corners vent each compartment.
of 1/4” marine-grade plywood for
tanks up to 151L (40 gal); use
When you need extra tankage
8mm or 9mm (5/16” or 3/8”) ply
consider making your own.
for larger tanks. Because the
Potable water and holding tanks
bottom and top overlap the sides
made of plywood coated with
and ends, you’ll need to deduct
epoxy resin are inexpensive,
double the thickness of the
simple to build and are easily
plywood from your height
custom-made to fit any tank shape
measurements. Decrease the width
or hull contour. Epoxy is the ideal
of the sides by the same amount to
tank material. It waterproofs the
allow for the overlap of the ends.
plywood yet won’t contaminate
To build a tank that conforms to the
drinking water and is resistant to
contour of the hull,
head chemicals. I’ve used
laminate multiple
wood-epoxy water tanks
sheets of thin
on Nutcracker
veneer to the
required
thickness
over a wood
form (mold),
then join as
described below.
Tanks
larger than
Figure 2
19L (5 gal)
should have
To form a fillet, apply a bead of thickened epoxy (use a syringe
internal
or a heavy-duty plastic bag with a small hole cut in one corner),
then pass a tongue depressor held at a 45° angle over the
baffles to
mixture to remove excess and form a smooth fillet. Use a putty
prevent the
knife to scrape the excess epoxy on either side of the fillet for a
liquid from
smooth concave edge (A).
dry
en
eH
ari
-M
ne
An
Anne-Marie Hendry
surging inside the tank. The
number of baffles depends on the
size of the tank. A 151L (40 gal)
water tank, for example, requires
two or three baffles spaced 30cm
(12”) or less apart to ensure
sufficient support. Cut deep
scallops in the lower and upper
corners of each baffle (see Figure
1) so the contents flow freely
between compartments.
Assemble the tank in two
sections: the main tank with the
baffles, then the top. Both are
assembled separately and
completely finished, then the top is
glued in place. Join the sides, ends
and bottom panels using cleats
(2.5cm/1”) triangular pieces of
wood) attached with thickened
resin. Use staples, small copper
nails or pipe clamps to hold the
panels in place until the glue sets.
Alternatively, bond the panels
together using fillets: epoxy
thickened with colloidal silica to a
peanut-butter consistency that,
when applied to an inside corner,
forms a cove-shape bead over the
join (Figure 2). For added
strength on larger tanks, cover the
fillet with fiberglass tape and resin.
The goal is to have rounded,
smooth corners. With either
method, apply thickened epoxy to
all plywood mating surfaces.
Scrape or sand off any excess
epoxy, then sand the wood (and
fillets) with 120-grit paper. Coat the
interior of the box and the
underside of the top with a
minimum of four coats of
unthickened resin. Apply three
coats “green on green” — recoat
when the resin is just slightly tacky
and before it reaches its final cure
stage (about 2-1/2 to 3 hours at
room temperature). After the third
coat let it cure thoroughly, then
sand to a glass-smooth finish with
120-grit paper. This ensures an
© DIY boat owner 2001 1-888-658-2628
23
TANKS
A removable wood-epoxy water tank fits snugly in the vee-berth and has two inspection ports for cleaning. A stainless-steel
cable with adjustable turnbuckle attaches to the bulkhead and leads around the tank to a floor-mounted pad eye to hold the
tank securely in place. A rubber gasket under the wire on the forward edge protects the tank from chafe.
easy-to-clean surface. Because
epoxy is transparent, add a white
pigment (paste or powder) to the
last coat at the rate of 5% by
weight so you can easily see the
scum when cleaning the tank.
Cut holes in the top for large
clean-out ports: install 10cm or
15cm (4” or 6”) screw-in plastic
inspection ports, positioned so they
provide access to the entire tank for
cleaning. On tanks with multiple
baffles, locate the ports between
each baffled section. Mark the
placement for the vent, fill and
discharge hose fittings, then glue
backing blocks made of 12mm
(1/2”) stock to the top exterior
where marked. When cured, drill
the holes. A typical potable water
tank has a 16mm (5/8”) vent, 3cm
(1-1/2”) fill and 12mm (1/2”)
outlet; a holding tank has one or
two 16mm (5/8”) vents and 3cm
(1-1/2”) inlet and pumpout.
Glue the top to the tank, and
hold in place with staples or clamps
until set. Apply three coats of resin
to the exterior of the tank, followed
by two coats of an enamel or
polyurethane paint. Install the hose
fittings with sealant, then securely
mount the tank in the boat.
A word of caution: wood-epoxy
tanks are not recommended for fuel
storage due to the risk of fire.
© DIY boat owner 2001 1-888-658-2628
24
PLUMBING 101
installing
a
PRESSURE-WATER SYSTEM
Tools &
Materials
Drill & bits
Assorted screw
drivers
Sharp utility
knife
You need not buy a new, expensive boat to
enjoy some comforts of home. Follow these
easy instructions for installing a pressurewater system then just turn a tap and water
flows. What could be better!
FLOJET model
2840 Water
Pressure System
Hose: 19m (3/4")
inlet,
FLOJET model 2840 Water
Pressure System mounted on
an engine room bulkhead.
Note strainer in foreground.
12mm(1/2")
outlet
All-stainless
hose clamps
W
hen we bought our boat in
1978, it was remarkably well
equipped for its day. It
boasted an electric water heater, a
pressure water system, an enginedriven generator (in addition to the
ordinary alternator) and two electric
heads. Since our philosophy at the
time was a keep-it-simple
minimalism, out came all of the
above. I don't recall the fate of the
water heater or pump, but one head
remained on the dock in Nassau
(with permission from the dock
owner), the other became a planter
in a Florida boatyard and the
generator found new practical use in
its recycled life as the basis for a
mooring in a Bahamas harbor.
Now, 20 years later and settling
into a different kind of liveaboard
lifestyle, the simple life has less
appeal. The idea of the easy life is
taking on new significance and so,
after years of a hand pump in the
galley and a foot pump in the head,
our classic boat is now equipped
with a very modern pressure-water
system.
Initially, plumbing might seem to
be one of those jobs requiring a
knowledgeable outside person, but
as more manufacturers have become
attuned to the "I'd-rather-do-it-myself"
thinking, the installation of such a
system fits in the category of the
average boat owner's capability.
All boat projects should be
planned carefully, to avoid do-overs
and to make sure everything you'll
need is on board. With this project,
the planning stage will establish the
shortest routes for hoses to follow
and the most centrally located place
for the pump, assuming it may be
© DIY boat owner 2001 1-888-658-2628
25
WATER SYSTEM
TROUBLESHOOTING:
REDUCE PLUMBING
SYSTEM NOISE
By Chris Beh
Positive displacement pump "noise"
can be attributed to many factors. The
way the pump operates lends itself to
some noise, inherent in these devices,
but you can reduce the amount of
noise transmitted to the boat by
carefully following a few installation
details.
Be sure to mount the pump on a
solid surface with solid supports
underneath. If you can knock on the
serving more than one faucet.
The system we installed is a
FLOJET (US$294.55) — an all-inone pump (Quad diaphragm unit)
and accumulator tank with a built-in
pressure switch and a separate inlet
strainer. Compact and lightweight, it
fits in a locker and weighs just 4kg
(8.8lb). Once installed, the pump
pulls water from the boat's water
tank and sends it to the accumulator
tank. With the accumulator tank, the
pump doesn't run constantly
whenever a faucet is turned on. The
tank retains enough pressure to
allow the water to flow for a short
time without the pump working.
When pressure in the accumulator
tank drops to a certain level, the
pump turns on to refill the water and
restore the pressure in the tank.
FLOJET's system also includes a
strainer installed between the water
tank and the pump. This prevents
any sediment that may be in the
water tank from reaching the pump
and fouling the valves.
Location, Location
Of course, the closer the pump can
be to the faucet(s) and the shorter
mounting surface and it sounds like a
drum, vibrations are going to travel
through it. Use the manufacturer's
supplied rubber feet to mount the
pump and don't overtighten. To
reduce vibration, use at least 45.7cm
(18") of high-pressure flexible tubing
between the pump and "hard"
plumbing both on the inlet and outlet
fittings. Elbow fittings cause turbulent
flow and back pressure on the pump,
increasing noise levels, particularly if
placed within the first 61cm (24") of
the pump outlet. Better to replace
elbows with high-pressure flexible
tubing.
Another source of plumbing noise
the hoses, the simpler your plumbing
maze will be. Our boat had a good
start: the center cockpit is
immediately aft of both the galley
and the head. The pump could fit
neatly in one of two huge seat
lockers or be mounted in the
engineroom beneath. The engine
room allowed easiest access and a
bulkhead was vacant. The FLOJET
unit can be either deck-mounted or
bulkhead-mounted to a solid surface.
If bulkhead mounted, the pump head
should be down or lower than the
motor. Once installed, the strainer
would be visible and easy to clean.
Installation
Gathering tools for this job is
especially easy: all that's needed are
a drill and bits, screwdriver and a
sharp knife to cut hoses.
First, assemble all the parts.
Besides the unit itself, have handy all
needed hose lengths, a good supply
of all-stainless hose clamps and
whatever adapters you may need to
connect faucet to hoses. Be sure to
use reinforced hose made for highpressure applications. And, of
course, you'll need the faucets(s).
is vibration from piping and fittings
where they pass through bulkheads
and behind drawers and shower
walls.
To check for noise, grab the
piping on either side of the pump.
Does the noise and vibration level
decrease while you hold the piping?
Turn on the tap(s) one at a time and
check which one(s) creates excessive
noise or vibration. Check the strainers.
Clogged strainers, as well as air leaks,
can make a pump labor and cause
noise.
About the author: Chris Beh is an
applications engineer for SHURflo in Santa
Ana, Calif.
The standard household kitchen
faucet might be too big for a boat
sink as it arches up too high. Bar
sink or laundry tub faucets are
better, having a lower arch or none
at all (faucet extends almost straight
out over sink).
Before mounting the accumulator
in position, attach hoses to the
pump: the inlet hose connects to the
water tank and the outlet hose goes
to a faucet(s). Screw the pump unit
into its chosen place with the
supplied four rubber mounting feet,
then run the hoses. Eventually, you'll
include all the required tee-fittings
that will lead cold water to each
faucet (galley, head sink and
shower) plus one hose into the water
heater and another out of the heater
and directed to each hot-water
faucet (Figure 1). But start with one
faucet; ours was the galley sink.
Securely fasten the strainer to a
bulkhead, cut the water supply line
from the tank and connect the ends
onto the strainer. Clamp all hose
connections securely.
Wiring
As with any wiring project,
remember to disconnect the power
© DIY boat owner 2001 1-888-658-2628
26
WATER SYSTEM
1
Shower Head
Water Heater
Galley Faucet
Head Faucet
Hot Water
Cold Water
Water Tank
Water Tank
Strainer
FLOJET (Mounted on Bulkhead)
Cross-section view shows
components installed in a
pressure-water system.
before you start. This is a very basic
job: take the negative (black) and
positive (red) wires coming off the
pump and connect them to the
appropriate distribution panel.
Splice an in-line fuse into the
positive wire. Check pump specs
for the recommended fuse size.
FLOJET models are available for 12, 24- and 32-volt DC systems, and
115-volt AC that plugs directly into
an AC outlet.
The tank should be pressurized
before starting the pump. Use a
bicycle tire pump to pump up the
pressure. Follow manufacturer's
instructions and check the pressure
after filling and before starting the
pump with a pressure gauge. Like a
bike tire, pressure can be reduced
by pressing the center pin of the
valve.
Start Up
See that the water tank is at least
1/4 full. Open the faucet(s) to
purge air from the system. Turn the
power on so the pump will start.
When air is out of the system, about
a minute or so, close the tap(s). The
pump will pressurize the tank, and
then turn off and on automatically
as required to maintain the pressure
in the system.
You could add another element
to the system: a water filter, for
good drinking water. If you're
dockside on a relatively permanent
basis, you can connect directly to
city water supply, but if you choose
to do so, install a regulator to
protect the pump from the high
water pressures (see "Now That
You Have Pressure Water..." on
page 36).
Next on our do-to list is to install
a water heater, shower and sump.
[For step-by-step instructions to
install a water heater see DIY 1997#1 issue, page 20 — Ed.]
About the authors: David and Zora Aiken
are the authors of Good Boatkeeping and
Good Cruising published by International
Marine. The Aikens currently live aboard a
1963 10.5m (35') Chris-Craft sloop,
Atelier, berthed in Grasonville, Maryland.
© DIY boat owner 2001 1-888-658-2628
27
PLUMBING 101
KEEPING DRY BELOW DECKS
Is your boat’s existing bilge pump system adequate?
Here’s the lowdown on pump types, flow rates, installation
options and other information you need to evaluate and
plan an upgrade.
By Nick Bailey
D
espite the fact that most boats
are fitted with one or more
bilge pumps, sinkings are
common nonetheless. I’m always
amazed how many boats are only a
corroded fuse or dead battery away
from sinking. Even more amazing is
the blind faith boat owners have in
what is often a very fragile and
inadequate pump system. Many
pumps are hard pressed to keep a
boat afloat at the dock, let alone in
the event of an emergency
underway. A properly installed and
maintained bilge pump system is
your second line of defense against
sinking, behind a watertight hull,
and so deserves your earnest
attention and resources.
Types of Pumps
Most bilge pumps are either
centrifugal (submersible) or positive
displacement (non-submersible) type.
Both types can run dry for sustained
periods without damage, unlike a
flexible impeller pump which
overheats and comes apart almost
immediately if run dry.
Centrifugal pumps (common
submersible pump) have a curved
solid impeller designed to sling
water entering from the center axis
of the pump housing into an outlet
pipe mounted tangential to the
housing. A centrifugal pump moves
water by momentum alone and as
no suction is created it won’t self
prime. Many have a detachable
base plate, fastened by screws in the
bilge and the pump motor assembly
snaps or twist locks into the base
plate. Slots incorporated in the motor
or base plate housing serve as a
debris screen to keep the impeller
from fouling. A discharge hose leads
to a thru-hull above the waterline. It’s
a very simple plumbing installation
in concept but one that is subject to
a variety of problems — connecting
a discharge hose often cuts actual
pump performance down to half (or
less) of rated capacity (see “Pump
Performance”).
Positive displacement pumps use
a reciprocating flexible diaphragm
or piston to force water out of the
pump on the down stroke and suck
water into the pump on the upstroke.
The pump inlet and outlet have a
one way flapper or duckbill valve to
ensure that fluid can only go in the
desired direction on each stroke.
Due to the suction created, pumps
are self priming and often mounted
remote from the bilge with only
intake hose and bilge strainer, a
useful feature for boats with a bilge
sump too narrow or inaccessible to
fit a submersible pump, or in shallow
bilges where bilge water level must
be kept to a minimum.
The weakness of diaphragm
pumps is their limited capacity. Even
electric diaphragm pumps don’t get
much above 1,200 gallons per hour
(gph), a capacity otherwise
expressed as 20 gallons per minute
(gpm). This is due to the inefficiency
of their one-gush-ata-time reciprocating action. Most
manually actuated bilge pumps are
the diaphragm type (i.e. Edson,
Bosworth, Henderson, Whale) with
rated capacities from 5 to 30 gpm.
As all diaphragm pumps are easily
crippled by debris lodging in oneway valves, a bilge pick-up strainer
or in-line filter must always be
installed.
Pump Performance
For all pumps, manufacturers
provide the rated capacity and flow
rate data. Nominal ratings are
based on “open flow” conditions; for
example, the pump is operating in a
bucket with no hose attached. This
nominal “maximum flow” rating
does not even remotely indicate how
a pump will perform in a typical
installation.
The hydraulic head pressure the
pump must overcome to push water
through the hose and up to the
discharge thru-hull governs realistic
pump performance. Two factors
contribute to head pressure: static
head — vertical distance from the
pump to the discharge thru-hull —
and dynamic head, which is the total
frictional resistance within the
discharge plumbing, usually
expressed as an equivalent to feet of
static head. Adding static head to
the dynamic head gives the total
head pressure (also expressed in
feet) that the pump must overcome.
Pump manufacturers usually provide
© DIY boat owner 2001 1-888-658-2628
28
KEEPING DRY
How Big a Bilge Pump?
There are no mandatory pump size
requirements for pleasure craft from
Figure 1
15
SAMPLE SUBMERSIBLE PUMP PERFORMANCE
3/4" outlet
1"
10
1.5" outlet
5
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
FLOWRATE (gpm)
the U.S. Coast Guard or even any
recommendations from the American
Boat and Yacht Council (ABYC). The
American Bureau of Shipping (ABS)
recommends that vessels under
19.5m (65') be equipped with a 24
gpm and a 12 gpm pump totaling
36 gpm (or 2,160 gph). If we
assume this recommendation is for
actual pump performance, then this
spec calls for a pumping capacity of
5,000 gph or larger, depending on
how restrictive the installation.
Without detailed small craft
recommendations your pump choice
largely depends on whether you
view it as a convenience to dewater
the bilge from minor leaks or as a
major safety system designed to
keep the boat afloat in the event of a
critical failure such as a broken thruhull or ruptured shaft log. According
to a graph (Figure 2) adapted from
Figure 2 - FLOODING RATES (gpm)
Depth
of Hole
outlet
WHALE
HEAD (feet)
information regarding the maximum
allowable head height and a graph
of flow versus head height (Figure
1).
Another important capacity
factor is whether full voltage is
available to power the pump. Open
flow rating is usually based on pump
performance with a 13.6-volt DC
power supply. (This represents the
voltage available while the engine is
running and alternator is charging.)
In actual usage, this voltage is rarely
available at the pump. The engine
may not be running, wiring may be
too small in gauge for the length of
run, there may be corroded
connections or the batteries may not
be fully charged. All these conspire
to reduce available voltage and the
pump’s actual performance. It’s
possible to theoretically calculate
what flow rate can be expected in a
given installation, but as a rule of
thumb assume a 50% reduction in
flow rate for a normal installation,
and even worse for an installation
with high head pressure. Since
submersible bilge pumps won’t lift
water beyond a 1.8m to 3m (6' to
10') head, it’s important to check the
pump’s performance specifications
in relation to the requirements of
your particular installation.
Diameter of
Hull Opening
the “Navy Salvor’s Handbook” by
Nigel Calder and published in
Professional Boat Builder No. 57, a
25mm (1") hole 30cm (1') below
waterline lets in 1,200 gph, a flow
rate which looks manageable. A
50mm (2") hole at the same depth
floods at the rate of 79 gpm or
4,760 gph, a situation equivalent to
the failure of a large thru-hull and a
flow rate that exceeds the rated
capacity of any bilge pump.
The largest popular submersible
pumps on the market range from
4,000 to 8,000 rated gph and
require 5cm or 7.6cm (2" or 3")
discharge hoses. Assuming the
typical 50% of rated performance,
even the 8,000-gph unit won’t keep
up with a 5cm (2") hole.
Nonetheless, if a system is to be
considered adequate for anything
other than routine dewatering, it
should be able to cope
with the most likely
failure, if not the very
worst case emergency.
1"
1.5"
2"
2.5"
3"
3.5"
4”
6”
1'
20
44
79
123
177
241
314
707
2'
28
62
111
174
250
340
444
1,000
3'
34
77
136
213
306
417
544
1,124
4'
39
88
157
245
353
481
628
1,414
5'
44
99
176
274
395
538
702
1,581
6'
48
108
192
301
433
589
770
1,731
System
Planning
Before upgrading an
existing pump system,
it’s necessary to
evaluate your boat’s
layout. The first
question is whether the
boat is divided into
© DIY boat owner 2001 1-888-658-2628
29
KEEPING DRY
- Ti p -
WATERPROOF
WARE
When you have a very wet boat
and need to keep connections dry
and corrosion free, use a watertight
plastic container and terminal strip.
A similar concept to the watertight
fuse box described in “DIY
Projects,” 1999-#1 issue, put the
terminal strip loose in the box, pull
wires through a single hole punched
in the bottom, attach ring
connectors to wires and connect
them to the terminal strip, mount the
box to any convenient nearby
vertical surface and snap on the lid.
Make sure the hole in the box faces
down so rising or dripping water
can’t get in.
— Jan Mundy
separate compartments that, if not
watertight, can at least retain water
up to a damaging level. Each
separate compartment should have
its own bilge pump sized to handle
the likely source of leak in that
compartment (see “Pump by the
Numbers” on page 16).
A 7.5m (25') cabin cruiser, for
example, typically has the engine
compartment separated from the
cabin by a watertight bulkhead. In
the cabin, there may be a 12mm
(1/2") head intake and two 25mm
(1") sink drains. A single 2,500 gph
should be adequate to handle one
broken thru-hull assuming two won’t
break simultaneously. In the engine
compartment the most common worst
case scenario is a ruptured water
intake or exhaust hose also
equivalent to a 25mm (1") flow rate
of 1,200 gph, so a second 2,500
gph unit should suffice, provided the
exhaust outlet stays above water.
A smaller open or cuddy cabin
23-footer is at risk of being
swamped in a big sea, or even in a
heavy rain. Although cockpits are
self draining, a lot of water still gets
in through engine hatch covers and
need the largest possible pumps to
handle the flow.
If your boat doesn’t have
separate compartments or large
limber holes draining into a common
bilge, two pumps on separate
circuits should still be considered the
minimum to provide back up in case
a pump fails or clogs. At least one of
the pumps should be of high
capacity to deal with a worst case
leak.
Sailboats often have a very
narrow or shallow bilge that cannot
accommodate a larger submersible
pump. A small submersible electric
pump or typical standard-equipped
manual diaphragm bilge pump,
although fine for routine dewatering,
is not adequate for emergency use.
Any boat that is configured in a way
that prevents the installation of a
properly sized electric pump is a
good candidate for a standby
emergency-only bilge pump system
(see below).
Larger boats have more
equipment, more and larger thruhulls that tend to be situated deeper
in the water. This increased depth
increases hydraulic head pressure
behind a leak and resulting rate of
flooding.
Emergency-Only Pumps
For small boats, an Edson selfcontained, portable pump kit fits in a
cockpit locker and is quick-toassemble when needed. A viable
strategy for an effective emergencyonly pump for larger boats would be
a standby high-capacity, enginedriven pump (pricey) or a large
submersible electric pump (more
affordable upgrade) mounted in the
lowest available space in, or near,
the bilge.
Rubber-impeller style engine-
Figure 3
B
A
Alarm (opt.)
On/Off/
Auto Switch
C
Manual pump
BIlge
strainer
DAVID AIKEN
Pump
Clutch pump unit
Pump switch
TYPICAL PUMP INSTALLATIONS
A: Manual diaphragm pump (i.e. Edson)
with inline strainer keeps debris from
clogging the pump.
B: Submersible bilge pump with separate
float switch, on-off-manual switch and
optional red light (and/or audible alarm)
operation indicator.
C: High-capacity engine-driven clutch
pump has manual on-off lever (or
electric) and includes bilge strainer.
© DIY boat owner 2001 1-888-658-2628
30
KEEPING DRY
driven pumps from Jabsco are
capable of self priming and are
engaged by either a level-actuated
manual clutch or by a remote switch
actuated electric clutch (Figure 3,
C). The largest version has a rating
of 5,000 gph at full speed (2,200
rpm) and a conservative capacity
rating at 3m (10') of head. Intended
for higher horsepower engines (30
plus), engine-driven units obviously
require you to become aware of the
leak before the engine drowns, so
some kind of high-water alarm would
be useful (i.e. Bilge Sentry, Ultra
Pumpswitch Senior). Like any
impeller pump, if the engine-driven
pump runs dry it will quickly smoke
the rubber impeller, but by then you
have presumably stopped the leak. If
you want to get fancy on electric
clutch versions, install a vacuumsensing switch that detects when the
pump sucks air and disengages the
clutch.
Figure 4
PRIMARY AND BACKUP PUMP INSTALLATIONS
3-way
Switch
A
Primary
pump
and switch
B
Alarm
(optional)
Secondary pump
and switch
3-way
Switch
Primary pump
and switch
Installation Guidelines
Manual bilge pumps (i.e. Edson) are
robust, simple devices and seldom
fail. Electric bilge pumps are also
robust and simple but reliability is
another matter entirely. When an
electric bilge pump fails, it’s rarely
the fault of the pump but more likely
to be a result of poor installation or
maintenance: faulty wiring, a
clogged pump inlet, and a stuck or
broken float switch. (See page 22
for complete installation details).
Positioning: A submersible pump
must be firmly fastened in the
deepest part of the bilge. If access to
the ideal spot is difficult, or you are
reluctant to drive screws into the hull,
mount the pump on an aluminum Lshaped bracket and fasten this to
anything convenient and solid, like a
stringer or rib. If you are planning to
mount two pumps, it makes sense to
have one larger than the other and
mounted higher up (Figure 4). The
Secondary pump
and switch
A: Both pumps on same circuit; B: Backup pump on separate circuit.
smaller pump (lower power
consumption) would be your every
day pump and the larger reserve,
back-up pump used when the other
fails, or the rate of flooding exceeds
the smaller unit’s capacity.
With planing powerboats, the
lowest point while underway may be
different from the lowest point at rest.
You may want a pump at each
location, particularly if there are
separate compartments.
Plumbing: Most hose sold for bilge
pump use is light plastic corrugated
stuff [Ed: Specs, standards and
recommended options for marine
hose appears in DIY 2000-#2 issue.]
Corrugations have the advantage of
making the hose flexible enough to
turn tight corners without kinking, but
they also contribute a significant
amount of resistance to water flow
adding to the dynamic head
pressure the pump must overcome.
Each bend, elbow and hose length
itself contributes to resistance. So, to
minimize adverse head pressure the
hose route should theoretically be as
short as possible, rise as little as
possible, have few bends and have
no corrugations. The discharge thruhull must also be a safe distance
© DIY boat owner 2001 1-888-658-2628
31
KEEPING DRY
PUMP BY THE NUMBERS
Owner of Galleon Jewelers and avid sportsfisherman, Captain Richard
Provenzano may be considered somewhat eccentric when it comes to
staying afloat. Moored in Sebastian, Fla., his 11m (36') Hatteras has
weathered numerous hurricanes, floods and the like which he largely
attributes to having seven pumps onboard. Starting at the bow are two in
the forward stateroom, one 1,200 gph unit in the bilge and one 800
gph high-water pump mounted 15cm (6") higher that attaches to the
drain sump from the shower. “When I’m shy on fuel, the boat’s bow
heavy in the slip,” says Provenzano, “and if the lower pump fails, the
boat won’t fill with water.” Mounted in the engine compartment are two
2,000-gph pumps under each engine. In the bilge below the
companionway beside the Racor filters is a Lovett pump. “This one is the
main pump.” Another two 1,500 gph pumps reside in the stern bilge.
This gives a total pumping capacity of about 11,000 gph. “It’s a lot of
pumps, but leaks happen.”
— Jan Mundy
above the waterline to avoid back
siphoning.
Back Siphoning and Check
Valves: Some systems may have the
bilge pump discharge installed below
the waterline with a check valve to
prevent back siphoning. If you do
this, your boat will sink — it’s not a
matter of if, just when. Every check
valve eventually gets a bit of debris
lodged in the flapper and when it no
longer seals the boat sinks.
Sailboats have particular
difficulty finding a good above
waterline location for the discharge
simply because when heeled over in
a stiff breeze the waterline on the
- Ti p -
leeward side may be up on deck
somewhere. Conversely, an outlet on
the windward side may now be 3.6m
(12') straight up from the pump
(Figure 5). On one tack the pump
wants to back siphon and sink the
boat, on the other tack the head
pressure is so great it may not pump
any water at all. There are three
solutions: reef sails to reduce heel;
lead the discharge hose to the center
of the tran som, if you have access;
lead the hose up to the deck head
and install a siphon break or riser
loop. Hopefully, the hose is now
above the heeled waterline and the
extra head pressure on the other tack
won’t cripple the pump. Never install
PUMP CYCLE METER
About 10 years ago, Rockland, Mass., marine surveyor David
McKie installed a bilge pump "minutemeter" on his boat. Developed
by a local inventor, the analog meter mounted inline with the float
switch and registered pump-operating time in minutes, similar to an
engine hourmeter. Recording meter readings before leaving the boat
and upon returning gave McKie an accurate audit of pump run-time.
We’re not aware of any off-the-shelf products available, but if you’re
handy with electronics, it’s a simple device to make.
— Jan Mundy
check valves for the reasons
mentioned above.
Powerboat manufacturers often
install the bilge pump outlet a few
inches above the waterline to avoid
annoying sounds of water splashing.
Beware of crowded cockpit parties
where excessive weight can
submerge thru-hulls. To avoid a back
siphon, the discharge hose should be
routed through a riser loop. Riser
height is a compromise between
avoiding a back siphon and
decreasing pump performance. A
46cm (18") riser ought to be about
right.
If you hate the thought of drilling
another hole in the hull for a thru-hull,
it’s possible to tee the discharge into
existing above-waterline outlets (i.e.
cockpit scuppers or sink drains) as
long as the hose rises high above the
waterline and includes a riser loop. If
in doubt, do not attempt.
Finally, make sure all hoses can’t
kink, are well supported and are all
double clamped with non-corrosive
clamps (see “Not all Clamps are
Equal” on page 35).
Batteries: Most submersible pumps
draw about 6 amps of 12-volt DC
current for every 1,500 gph of
capacity. If your boat has a 90-amp
battery at 80% charge (which is
optimistic) you could theoretically run
a 3,000 gph pump (or two 1,500gph units) for three hours before you
use up half the available juice. The
other half of the battery’s charge will
be available at lower and lower
voltages, so pumping efficiency will
fall off rapidly.
If you have the motor running or
plugged into shorepower with the
battery charger going, battery
capacity is not a problem. If you are
adrift with a disabled engine and
taking on water, a good bilge pump
system doesn’t mean much if your
batteries can’t supply the needed
power until rescued. There are only
two kinds of marine batteries;
© DIY boat owner 2001 1-888-658-2628
32
KEEPING DRY
3
5
4
2
1
7
6
1.Unlike submersible pumps that continuously cycle on and off, Rule Mate pumps
have an integral float switch that turns the pump on only when water level rises. 2.
Conventional float switch. 3. A high-water alarm triggered by an electrode provides
early warning to irregular bilge water levels. 4. Ultra Pumpswitch has an non-jamming
enclosed float and magnetic switch; Senior model features a high-water alarm 5. A
"smart" bilge switch, the Bilge Buddy shuts off the pump switch when it senses
petroleum products in the bilge; 6. Compact and quickly assembled when needed,
Edson one gallon-one stroke portable pump kit includes carrying board and quickconnect couplings. 7. A manual override switch or a three-position on off auto switch
lets you manually pump out the dregs and override a stuck float switch.
cranking batteries or deep cycle
batteries, which cost two to three
times as much but last five times as
long. Don’t skimp on batteries if you
want your pumps to keep your boat
afloat in an emergency.
Wiring: Bilge pumps are probably
the only electrical item that should
remain powered even when the main
switch is turned off. Wire directly to
the battery terminal or more neatly to
the battery connection post(s) on the
back of the main switch.
Pump performance suffers a lot
from small voltage drops due to line
losses, so when specifying wire sizes,
ABYC 3% voltage loss tables should
be used (refer to “Wiring
Handbook,” DIY 1998-#4 issue). For
example: a pump draws 15 amps
and you need 9m (30') of conductor
to power it, the tables specify 8
gauge AWG wire to keep voltage
losses within 3%.
Making durable connections to
the float switch and pump is always a
problem in an area that is often wet,
particularly in saltwater. Corrosion at
these connections is the most
common cause of pump failure.
Corrosion increases electrical
resistance, which in turn can cause a
connection to overheat or break.
Bilge pump wires and
connections must be watertight,
preferably crimp-on connections with
self-adhesive, heat-shrink terminals.
No wire nuts (Marette plugs) or tape.
Specialty UL-approved multi-strand
Boat Cable (or BC) is available for
bilge pumps (two or three colorcoded conductors 18 to 14 AWG
with water-resistant jacket). All
connections should be above the
maximum bilge water level or as
high as possible, fastened securely
and away from float switches,
control cables, shafts, etc.
Fuses: Corroded fuses and fuse
holders are the next most common
reason pumps won’t go when they
ought to. Because of this weak link,
some surveyors even disagree with
ABYC recommendations that a fuse
or breaker should protect this circuit,
like all others. Submersible pumps
can overheat and even melt but
rarely catch fire. The big danger
here is a short circuit in wiring to the
pump causing a fire. To minimize
that possibility and preserve circuit
Figure 5
DAVID AIKEN
SYSTEM COMPONENTS
Static head varies in sailboats when
heeled and siphoning potential varies
depending on the tack.
© DIY boat owner 2001 1-888-658-2628
33
KEEPING DRY
protection keep any in-line fuses out
of the bilge and in the closest
available location with quick access.
Check and clean terminals often,
and replace fuses every year
regardless.
Automatic
Pump Switches
Generically known as float switches,
there are many different kinds
available. All of them can
malfunction and frequently do, most
likely from oily, hairy, slimy debrisfilled sludge that inhabits most
bilges. Switches become so badly
fouled that they clog or stick. If stuck
in down position, the boat might
sink. If stuck in the up position, your
pump runs on and on until it
eventually burns out or flattens your
battery — then the boat sinks.
The first step in keeping the float
switch and pump alive is to keep
your bilge clean and free of debris.
Maybe it’s time to add a drip pan
under the engine [Ed: refer to DIY
Projects, 1996-#4 for how to build
one] or a separate graywater sump
for the shower. Don’t pump fuel —
or oil-mixed bilge brew overboard. It
pollutes and is illegal in many areas
with fines up to US$5,000.
If the bilge sump is narrow and
long enough to allow a few inches
of water to surge back and forth it
can beat relentlessly on an exposed
float switch until the hinge or wires
break. If your boat has this sort of
layout you need a switch housed in
a protective cover (which
unfortunately can foul up) or install a
cheap baffle to protect the switch.
Installing the switch near a bulkhead
with the hinge facing the surge will
also help protect it. Wiring inside a
switch not rated to carry the same
amperage as the pump draws, will
overheat, causing premature failure
due to fatigue or corrosion.
In a sailboat the float switch
must be on the same fore-aft axis as
the pump, otherwise it won’t operate
in the same depth of water when the
boat heels. This causes the pump to
run dry on one tack, yet not trigger
the pump when needed.
Although a switch will work
installed on a pump’s either positive
or negative feed, don’t install it on
the negative side. This leaves the
pump energized at all times. In
saltwater there is a high risk of stray
current leaks to ground. Any current
leak from the pump will destroy it
and possibly any metal thru-hull,
which provides a path to ground.
Proper bonding of thru-hulls will
delay but may not prevent damage
from stray current galvanic
protection. [Ed: DC bonding systems
and corrosion will be covered in
upcoming issues.]
Make sure the float switch is set
up to shut down the pump long
before it begins to suck air,
otherwise it will either never shut off
reliably or water remaining in the
hose will drain down and re-trigger
the switch, setting up an endless
cycle. You may need to choose a
switch with a larger vertical distance
between the trigger points for on
and off Some panel switches have a
provision to show an indicator light
when the pump is activated; you
may otherwise be unaware that the
pump is working. Another useful
gadget available is a cycle counter
so you can gauge typical daily or
weekly pump use and look for any
sudden jumps in pump activity that
may indicate a packing gland
beginning to leak or a bad plank
seam.
Another potentially useful
accessory is a high-water alarm,
such as a separate unit that’s
triggered by a secondary float
switch or by the backup pump. If you
are away, a high-water audio alarm
or flashing light can also alert your
dockside neighbors or marina staff
that your boat is in trouble. [Ed:
- Ti p EMERGENCY
AUX PUMP
A raw-water cooled inboard
engine is easily converted to
double as an emergency bilge
pump. Installation requires
three valves, a couple tee
fittings and hose connections.
You’ll find complete how-to
instructions and configuration
options in "Modifying Rawwater Cooling Systems,"
article in DIY 1997-#3 issue,
now available in PDF format @
DIY ONLINE
— Jan Mundy
Consider upgrading to one of the
newer, high-tech switches, such as
the electronic "smart" Bilge Buddy or
magnetic Ultra Pumpswitch. These
self-contained, non-jamming switches
cost as much as $100 more than a
standard "cheap" float switch — buy
the best you can afford.]
Conclusion
There is no fail-safe bilge pump
system that will keep you afloat in all
circumstances. It’s important to
understand the capabilities and
limitations of your own system and
never take it for granted, especially
any automatic system. While
underway, there is no substitute for
regular manual checks of bilges as
part of normal watch keeping.
When at a mooring, no automatic
system can ever substitute for weekly
visits to your boat just to make sure
it’s afloat.
About the author: Nick Bailey is
service manager of Bristol Marine in
Mississauga, Ont., and an avid
Thunderbird-class racer.
© DIY boat owner 2001 1-888-658-2628
34
PLUMBING 101
NOT ALL CLAMPS ARE EQUAL
Hose clamps vary greatly in quality and construction. What you
may think is an "all-stainless" clamp could sink your boat.
By Jan Mundy
Replacing a failed submersible pump in one of our 6.6m
(22') test boats prompted an investigation into hose
clamps.
You’ll note
in the photo (left)
the badly
corroded
clamps
connecting
hoses to belowwaterline thruhulls not
equipped with
seacocks. Like most boaters, we hadn’t examined the
clamps until the need arose. Besides saltwater (this is a
freshwater-used boat), cleaners and chemicals in bilge
water can and do accelerate corrosion of isome metals.
Clamp failure in the bilge can sink
a boat; clamp failure on a fuel
line can be fatal.
Close inspection
of five brands, four
obtained from marine
stores and one
removed from our
test boat, netted
surprising
results. Many
clamps sold are
not all 100%
corrosion-proof
Two hose clamps (left and
stainless-steel construction.
center) with magnetic,
Stamped on every clamp
potentially corrosive screw
screw was "All Stainless,"
pins and housings stamped
yet the clamps in our test
"All-Stainless" purchased
from a local marine store,
boat had badly rusted
screws and corroded bands and clamp (right) removed
from test boat. Perforated
underneath the screw
bands encourage crevice
housings.
corrosion and are prone to
Although clamps may
cracking.
be labeled all-stainless,
there are different grades
of stainless; clamps are
commonly made of 304,
316 or 400. Series 302,
304 and 305 stainless,
commonly referred to as
Only two of five
18-8, are non-magnetic,
"all-stainless"
but freely succumb to
clamps passed the
magnet test: AWAB
crevice corrosion. More
and Ideal All 316 SS.
expensive is non-magnetic
316, a lower carbon,
higher nickel and chrome content stainless which makes it
more corrosion resistance. Type 400 stainless is magnetic
and corrodes rapidly in the marine environment.
Our magnetic test found three clamps with magnetic
screws and housings, which means they are highly
corrosive. Two clamps, AWAB and Ideal All 316 SS held
no attraction.
Our tests prove that boaters once again must be
aware of what they’re buying, and when it comes to
purchasing clamps, look for either AWAB or equivalent
"All 316 Stainless" clamps. You’ll pay more, but it’s
unlikely you’ll have to replace them. When in doubt,
carry a big magnet.
Lastly, contrary to popular belief, tighter is not better.
Use the manufacturers recommended tightening torque,
typically 45 to 55 inch-pounds, or secure as tight as
possible with a screwdriver. Using a ratchet or socket
wrench overtightens clamps and damages hoses.
Details of a premium hose clamp: all-316 non-metallic, noncorrosive stainless; solid non-perforated band prevents metal
fatigue and breakage, and uniform clamping force; stamped
band threads on outside offer high clamping force; smooth
band inside with no perforations and rolled edges prevent hose
damage; pin housing designed to maintain circular shape.
© DIY boat owner 2001 1-888-658-2628
35
PLUMBING 101
BILGE PUMP SENTINEL
Easy to add to an existing
system, this simple alarm
sounds every time the bilge
pump cycles.
By Paul Shard
This may be the most important upgrade you add to
your boat — an alarm that sounds when your
automatic bilge pump cycles. Water flow from a
leaking stuffing box or parted hose-clamp can quickly
overcome a pump, a plight that can continue
undetected, as the boat sinks lower in the water.
Numerous cases have been reported of boaters
opening the hatch, stepping down into the cabin into
a foot of water. With hundreds of gallons sloshing in
the bilge, it becomes very difficult to find the source
of the leak.
The solution is to install an audible bilge alarm.
Any water in the bilge is detected immediately. The
alarm should be audible both in the cabin and on
deck, even when the engine’s running (alternatively,
consider more than one alarm). If you already have
an electric pump with a separate float switch, an
alarm is added easily. If you don’t have an automatic
pump with float switch, it may be a good time to
install one.
To connect an alarm to an existing bilge pump
switch, purchase a 12-volt DC alarm from a marine
or electronics supply store. Models with indicator
light and buzzer are usually mounted in a panel.
Buzzer-only units can be mounted anywhere within
hearing range. A location near the bilge pump switch
simplifies wiring. Wire the alarm’s hot (positive) lead
to the terminal on the back of the bilge switch that
manually turns on the pump (Figure 3, B on page
30). This terminal also has power to it when the float
switch turns on the pump. Connect the other wire to a
negative bus bar. Now test the system: switch the
bilge pump to manual or lift the float switch to
activate the pump. Every time the float switch turns on
the pump, the alarm also sounds.
Some boats have “intelligent” bilge pumps with
integral float switch in the same housing. Some
models (Rule Mate) are wired with a manual
override. If not so equipped, the easiest option is to
add a separate float switch and alarm. Mount the
float switch above the existing automatic switch so
the alarm sounds when water rises above normal.
One alternative, if you have room in the bilge, is to
install a smaller second pump with an alarm (as
described above) but mounted lower in the bilge.
Now this pump sounds the alarm when it detects
water; the original pump becomes a backup.
Boat motion may occasionally activate the switch
then turn on the pump and alarm, though no water is
actually pumped overboard. On a rough day, this
gets annoying. Commonly caused by a poorly
designed float switch or improper mounting, raise the
switch slightly higher than the pump. If this doesn’t
resolve the problem, consider a switch with a larger
vertical distance between the trigger points, such as
the Ultra Pumpswitch, Groco Bilge Pump Control Kit
or other ones that compensate for backflow without
activating the switch.
Installed on our 37-footer, “Two-Step,” this alarm
system has been problem-free for 10 years and
35,000 miles of international cruising. On four
occasions it alerted us to potentially dangerous
problems. One time the dripless shaft seal had
jammed with debris when we put the motor in gear
and water was pouring in. It was easy to fix since the
water level was still very low in the bilge and I could
see the spray leaking out the seal. Occasionally the
alarm activates in the middle of the night, usually
after a heavy rain. Personally I don’t mind hearing it
cycle on for a few seconds, then go off again. It’s
when it comes on and stays on I take action.
Altogether, it’s the cheapest stay-afloat insurance we
have on board.
About the author: Paul Shard and his wife and
business partner, Sheryl, are the authors of “Sail
Away! A Guide to Outfitting and Provisioning for
Cruising” published by Pelagic Press. You can follow
their adventures at www.searoom.com.
- Ti p - LOSS COVERAGE
If your boat should sink are you insured? A
loss due to “unknown” causes will likely be
covered by the insurance company. Should a
survey prove that the sinking was due to lack
of maintenance or negligence, it’s possible
your claim might not be covered. Check your
policy now for “exclusions” ere you need to
file a claim.
— Jan Mundy
© DIY boat owner 2001 1-888-658-2628
36
PLUMBING 101
BILGE PUMP
REPLACEMENT
By Jan Mundy
Boatbuilders often mount bilge pumps
in inaccessible areas deep in the
bilge, usually before the deck is in
place, unmindful of replacement or
servicing. Particularly in small
powerboats, replacement demands
crawling through a small hatch, often
working blind. (Use a mirror for a
rearview look if you’re adept at
working backwards.)
Submersible bilge pumps typically
run for nine years before failure and
less for leaky boats where the pump
regularly cycles or dry boats, where
lack of use causes corrosion or grit,
sand or salt build-up. Failure also
occurs when water gets into the pump
through wires or shaft seal — the
pump fills with water then goes
through several freeze-thaw cycles.
This was the case with a Mayfair
pump in one of DIY’s test boats when
it failed to run after 10 years of
normal use in freshwater. Replacement
is an easy one-hour job, after
removing the old unit, drying the bilge
and sealing the original mounting
holes.
1 If you’re lucky, the original pump
has a detachable base, so removing
mounting screws is easy. The Mayfair
unit didn’t; removal meant dangling in
a narrow stern locker, groping with
hands, trying to locate three Phillipshead screws. For bilge work, an extralong handled screwdriver comes in
handy. Note the corroded hose
clamps in the photo (above).
2 Since pumps rarely have the same
footprint, the next step is to seal the
original mounting holes with 3M
Premium filler, 3M 4200 (I prefer the
Fast Cure) 5200 or equivalent brand.
Be sure holes are dry before filling.
While you’re down there, inspect the
hull for other openings in the hull and
properly seal. I found a few extra
holes drilled by the manufacturer, none
were sealed. (The very first item on
your to-do list after purchasing a boat,
either new or used, should be to rebed
every piece of hardware, caulk voids,
holes, etc.)
3 Placement of pump and switch is
critical. Even when replacing, it’s best
to doublecheck the
location.
Position the
pump base
(strainer) so
the nozzle
aligns with
the
discharge
hose and
locking tabs line up with the pump
body. The float switch should mount at
least 6mm (1/4”) above the strainer so
it’s not automatically running all the
time. Rule pumps come with an
adapter that connects the switch to the
pump base and positions the switch at
the proper height. Pumps are prewired
and include fasteners; you’ll need to
supply sealant and heat-shrink
connectors.
4 Carefully drill a pilot hole in the hull
for the pump base, liberally caulk
around
the hole,
then
fasten
base
with
supplied
screws. Don’t drill through! Never
mount base directly on a cored hull —
a leaking fastener can quickly
delaminate cores below the waterline.
Instead, install a hardwood (teak or
mahogany) backing block, then attach
base to block.
5 Connect the hose, double clamp (if
enough clearance on hose barb) and
install the pump switch.
6 You have an option of wiring the
pump for manual or automatic
operation.
Since this boat
already had
an automaticmanual pump
control, we
stripped the
lead ends, connected negative and
positive ends to the original wires
leading from the panel and battery,
routing the wires high, just underneath
the deckhead. Ends were crimped
together using adhesive-lined, heatshrink connectors. If you don’t have
any, seal the connectors with sealant.
Note: positive lead from bilge pumps
should connect directly to the positive
battery post so as not to accidentally
disconnect with the master switch.
Also, all pumps must be fused and
with the proper size fuse or a pump
may overheat and blow a circuit. The
original pump installation included an
in-line 6-amp fuse, the new Rule pump
required a 9-amp fuse.
7 Not included but recommended is a
protective float switch cover. For extra
reliability, add a second switch
mounted
slightly
higher.
Better yet,
add a
second
pump.
© DIY boat owner 2001 1-888-658-2628
37
PLUMBING 101
WHAT YOU SHOULD KNOW ABOUT HOSE
Hoses are essential to keeping your boat afloat and operative but many
boats are equipped with inferior, non-marine-rated hoses. Here’s how to
survey and upgrade your boat to comply with today’s performance and
safety standards.
Story and photos by Jan Mundy
M
any boats built before
1990 and some after,
were assembled from
readily available materials, such as
highly corrosive automotive wiring,
inexpensive heater and fuel line hoses
and household plumbing fittings, with
little concern for boatbuilding
standards, either mandatory or
voluntary.
Nowadays, the installation of
most boat systems are regulated by
the Coast Guard, American Boat and
Yacht Council (ABYC), National
Marine Manufacturer’s Association
(NMMA), Lloyd’s and others. Though
some standards are voluntary and not
always adopted by boatbuilders, you
should adapt these when replacing or
upgrading components. This ensures
your boat will, at the very least, pass
a survey or insurance claim if the
surveyor or adjuster is standardsliterate, and you can avoid failures
Certified hoses for use on boats: (top)
Hard-wall (“R2” designated), wet
exhaust and water intake hose, SAE
J2006 rated; (middle) Coast Guardcertified fuel fill hose that meets fire
resistance (“A”) and lowest fuel
permeation (“2”) standards; (bottom)
Certified fuel distribution and return
hose meets fire resistance (“A”) and
highest fuel permeation (“B”)
standards. Gasoline-powered boats
must have certified fuel hoses to pass a
survey or insurance claim when done
by a competent surveyor or adjuster.
Non-approved automotive hoses
installed in early ‘80s on author’s
7.5hp diesel engine: (top) cheap,
highly-abrasive corrugated fuel
fill shown on right side; very thinwalled, non-Coast Guardapproved fuel distribution line;
common heater hose for rawwater exhaust shown on left side.
Note split hose wrapped over soft
heater hose (left side) to protect from
abrading on bulkhead. (bottom)
Automotive heater hose connects to
exhaust manifold. All hoses have since
been upgraded to marine spec after
researching for this article.
by inferior products.
Attending a seminar presented by
Bill Shields of Trident Marine at IBEX
‘99 (a trade show for boatbuilders),
prompted me to inspect the hoses on
my own early-‘80s-built boat. What I
found wasn’t pretty and unsafe,
especially engine hoses. If you
haven’t upgraded hoses on your boat
lately, read on.
Hose approved for marine use
should be Coast Guard certified, as
required for gasoline-carrying lines, or
constructed to meet minimum
performance and quality standards.
Though generally more expensive
than non-marine-rated hose, using
such products insures greater service
life and safety. Consider these
examples. When a raw-water-cooled
engine develops a blockage and the
engine overheats, an automotive
heater hose would likely burst. Spill
solvent on a cheap PVC hose and it
quickly dissolves. A ruptured nonmarine hose on an engine or gen-set
raw-water connection, air
conditioning, bilge pump, head and
livewell intakes or any hose
connected to a below-waterline thruhull can sink your boat. Likewise for a
leaking cockpit drain hose — should
it rain and the bilge pump can’t keep
up with the water flow, the boat will
surely sink. Non-standard engine
exhaust hose with pinhole leaks can
result in deadly carbon monoxide
poisoning and possible flooding.
Breach an unrated diesel fuel line or
holding tank hose and you’re
guaranteed to have the contents
dumped into the bilge, creating a
very dangerous, or noxious, situation.
Blow a non-certified gasoline line and
the boat becomes an explosive shell.
Hoses for marine use are often
labeled with the standards
classification, either SAE, Coast
Guard, NMMA, ISO, UL or Lloyd’s;
the manufacturer’s identification
number, usage, the year
manufactured plus other
classifications as specified for each
particular application. When
purchasing approved hose, also
examine the construction: check that
the hose ends have the same inside
© DIY boat owner 2001 1-888-658-2628
38
ABOUT HOSE
(left) Very soft, non-reinforced
automotive heater hose commonly
found in older boats and on author’s
boat for raw-water engine intake.
(right) Overtightening the hose clamp
has resulted in the thin-walled
automotive heater hose being crushed.
A hose failure could sink this boat.
diameter; examine the wall thickness
as thin-walled hose easily kinks and
has poor abrasion resistance; and
check that it’s reinforced with wire or
synthetic yarn (usually polyester).
Now that marine-rated brandname hoses are readily available, it
makes good sense to purchase the
best you can afford and of the proper
material and strength rating. Since
doing the research for this article, I’ve
replaced all the automotive engine
hoses on my boat and now have
premium quality, smell-free head
hoses. Next time you’re onboard your
boat, I suggest you inspect all the
hoses and upgrade, based on the
following specs, as needed.
Fuel Hose
Gasoline-carrying hoses on inboard
and stern drive boats are the only
ones that must by law meet Coast
Guard standards. Look for hoses
labeled “SAE J1527,” or less
common, “UL-1114.” Labeling on fuel
hoses also includes: classification of
resistance to fire, either “A” for fire
resistant, “B” for not fire tested (for
outboard use only); and fuel
permeation, either “1” which is the
Wall thickness of
Coast Guardcertified fuel line
hose (pictured) is
more than twice
the thickness of
automotive fuel
line.
highest permeation requirements for
gasoline distribution and return lines,
or “2,” a less-stringent requirement
commonly used for gasoline fuel fill
and vent hoses, and all diesel hoses.
There are currently no mandatory
standards for diesel or outboard
engine applications.
Exhaust Hose
Since 1999, flexible rubber hose,
bellows and elbows used in wet
exhaust systems must comply with
SAE J2006 standards and be so
labeled. This means that the hose is
temperature-rated at 593°C (1,100°F)
for two minutes, the equivalent of
running the
engine at
full power
for two
minutes.
Wet
exhaust
hose
Vetus double-steel
reinforced rubber
should also
exhaust hose is very
be flexible,
flexible, has Lloyd’s
thick
Register of Shipping
walled, and
approval and rated for
resistant to
100°C (212°F).
cold, heat,
abrasion, antifreeze and oil. Various
compounds are offered depending on
application and your budget. The less
expensive high-temp black 100%
EPDM rubber withstands 121°C
(250°F) maximum continuous. More
expensive is 100% silicone hose with
polyester reinforcement and molded
silicone-EPDM blend withstands
176.6°C (350°F) maximum
continuous. For extreme high-heat
applications, premium-priced NomexExtra thick-walled
engine coolant
hose (or for drain
or sanitation uses)
with wire helix
between two-ply
reinforcement has
excellent
flexibility and
bend radius.
molded or -reinforced 100% silicone
rated for 260°C (500°F) maximum
continuous lasts up to six times longer
than economical black EPDM rubber
hose.
Additional labeling on some
brands rates the product’s flexibility:
“R” for soft-wall, “R2” for hard-wall,
and “R3” for exhaust connectors. Softwall hose, commonly used for straight
connections, is reinforced with
multiple yarn plies. Hard-wall hose is
wire- and yarn-reinforced, preferably
wire sandwiched between two plies.
Flexible elbows and hose bellows
with an “R3” rating easily mold into
the tightest bends to compensate for
engine movement, vibration, noise
and misalignment, and reduce engine
back pressure.
Engine Coolant Hose
Hoses that circulate engine coolant
water must resist kinking, heat,
antifreeze and oil. A heavy-wall, twoply rubber hose, with or without wire
reinforcing, is recommended, or
substitute premium automotive black
heater hose or blue silicone hose,
both rated to meet SAE J20
standards. Some coolant hoses are
also reinforced with synthetic yarn.
For high-temp applications, Trident’s
Premium Blue Silicone hose has a
maximum continuous rating of 287°C
(550°F).
Raw-Water
Pick-up Hose
Any hose connected to a thru-hull
located below the waterline that
delivers raw water to an engine,
head, air conditioning and livewell
should be the best hose purchasable.
Don’t rely on corrugated hose — a
rupture could sink your boat. There
are no standards for this hose, though
it’s recommended to use twoply,
wire-reinforced, heavy-wall rubber
hose, the type used for engine
exhaust (SAE J2006 R2 or
© DIY boat owner 2001 1-888-658-2628
39
ABOUT HOSE
equivalent). Such hose won’t kink nor
collapse under suction if the rawwater screen becomes clogged.
Potable Water Hose
According to ABYC and NMMA
standards, water hoses must be foodgrade or FDA-approved, usually PVC
(polyvinyl chloride), preferably
smooth-walled and opaque rather
than clear as light encourages algae
growth. Never use rubber hose as it
imparts a foul smell in the water.
Pressurized cold-water systems
require reinforced hose for water
distribution, typically a clear or white
hose with red, blue and/or white
polyester yarn tracers. Both
pressurized and non-pressurized hotwater systems, where lines carry
60°C (140°F) water or higher,
require reinforced rubber hose.
Water tank fill and vent hoses
commonly use smooth-walled rigid
hose. Alternatives to hose for all
applications are rigid household-type
water pipe (different types for
carrying cold and hot water) and
piping systems offered by Whale and
Flair-It. (For detailed information on
Cheap multiflex corrugated hose
collapses in suction applications,
ruptures easily and reduces water flow
by up to 30%.
cuffs, is the worst option for bilge
pump intakes or for connecting pumps
to thru-hulls. Sure it’s resistant to oil,
water, easily bends around tight
corners and lasts a long time. But kink
it and the hose cracks. Chafe it and it
punctures. And the corrugations and
cuffs reduce water flow by 30% and
higher. (For more information on bilge
hose and water volume, refer to DIY
2000#1 issue.) Most quality
boatbuilders have replaced
corrugated hose with a more durable
nearly-as-flexible smooth version.
Drains
Flexible, heavy-walled rubber water
intake hose that doesn’t kink or
abrade is recommended for cockpit,
sink and shower drains. Alternatively,
you can use smooth vinyl or PVC
tubing, depending on the installation.
Sanitation Hose
(top) White PVC smooth-wall hose
commonly used for head and potable
water applications; (middle) Premium
choice odor-resistant, heavy- and
smooth-walled, reinforced, premium
black rubber sanitation hose; soft-wall
portable water hose reinforced with
multiple yarn plies, commonly used for
straight connections.
installing and troubleshooting
freshwater systems, refer to DIY
1997-#1 issue.)
Bilge Hose
Cheap multi-flex corrugated hose, the
stuff with the equally spaced molded
Sanitation hose on boats must contain
sewage that is about 30 times more
Use a smooth wall, wire-reinforced hose
(top) first to do the job before selecting
the cheaper, corrugated hose (bottom).
concentrated, especially vacuum-type
toilets that have very low water
content, than residential sewage. This
is not an easy task. Such hose must
be flexible, kink-resistant and more
importantly, odor-resistant. Often the
only type offered in marine stores,
and commonly installed on boats, is
food-grade, smooth-walled white
PVC. Not the best selection as odor
permeation is commonplace –- before
upgrading, I replaced cheap head
hoses every season as part of my
spring commissioning chores.
Stink-resistant alternatives, but not
readily available, are gray antibacterial hose and the smooth, heavywalled, premium-grade, less odorous,
black rubber hose. Either is a better
choice than conventional PVC hose,
but about twice the cost, however,
they won’t need replacing as often.
Some boat owners have had good
success with Schedule 40 or Schedule
80 pipe, supported every 1.8m (6').
Installing short hoses, minimizing
connections and limiting use of Yvalves that can trap sewage also
helps to reduce odor-causing
problems. (For step-by-step head and
holding tank installations and troubleshooting, refer to DIY 1997-#2.)
Although there are no
recommended standards for
sanitation hose, it’s often labeled with
the type and manufacturer. Knowing
this information helps to identify your
replacement options.
Ducting
Factory-supplied flexible vinyl ducting
used for heat and air conditioning
systems punctures easily. Better to
replace it with more durable, heavierwalled ducting.
Propane
Hoses used onboard for propane
appliances must comply with UL 21
and must be assembled with swaged
end fittings. All installations must
comply with ABYC A1.
© DIY boat owner 2001 1-888-658-2628
40
PLUMBING 101
HOW TO PLUMB BENDS
Plumbing a bilge pump, cockpit
drains, sink or thru-hulls often
necessitates bending hose at acute
angles. Most rubber water hose
collapses when tightly bent, and the
cheap multi-flex corrugated stuff that
does bend punctures easily and
should never be used in critical
installations. Vetus exhaust hose is
the perfect solution. Form this hose
into a tight coil and it retains its
inside diameter without crushing or
kinking. Unlike other exhaust hose, it
can be used in pressure applications.
The 50mm (2") hose, for example, is
rated for 174 psi (or 12 bar). It’s
available in various diameters
starting at 30mm (1-3/16") ID. Vetus
black exhaust hose (look for the
yellow stripe) is expensive at US$8
per foot for the 50mm (2") size, but a
better option than using inferior hose
or PVC tubing and adding elbows.
— Jan Mundy
© DIY boat owner 2001 1-888-658-2628
41

Tip - cichlidfish.net

Transcription

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