Furling Gear and Trailers

Single handed Dabbing
Part 3
Furling Gear and Trailers
Performance
I can’t help it but I race other boats when I'm in the Dabber. It happens like this. If I’m
sailing down the estuary and spy a sail I will try to overtake it. The trouble is that the crew of
the other vessel have no idea that it’s a race. They’re just enjoying a sail and watching the
world go by while I’m working hard searching for catspaws, windshifts, wave sets and
favourable eddies and making course, rig and centreboard adjustments to suit. On one
occasion I remember following a reasonable sized cruiser about six miles along the coast
before drawing abeam. I also remember the long beat back.
It seems to me that on the Dabber there is one rig adjustment, apart from sheet trimming,
which has an effect greater than any other. It’s difficult to be objective about this as you can’t
detect an increase in speed of the order of tenths of a knot. My GPS shows tenths of a knot
but won't be accurate to that level. You’d need initial accuracy coupled with fancy averaging
to show what I’d like to see. The problem is that a boat’s speed is not constant and every
variation in wind and every wave slows and accelerates the boat. It’s interesting to note that
the performance difference between the earliest and the latest Flying Fifteens is reckoned to
be only 40 seconds per hour.
There is however, a very effective way to fine tune sailing performance and that is to race a
one design. If you are alongside a boat which is identical to yours you have a reference point
for relative speeds and can fine tune accordingly. I’ve never come across another Dabber
while I've been sailing mine but it would be really interesting to compare them.
So how do I trim the sails for best performance? I’d use tell tales but as you can’t see through
Dabber sails I do it by eye, adjusting to reduce wrinkles and trying to achieve what I imagine
an efficient aerofoil looks like. This will, of course, only approximate to an efficient trim but
it’s all I can do.
I know it’s a Dabber and I promise I’m really not obsessed with performance but I still can’t
leave a sail badly set.
So what is this all important rig adjustment?
1
The tack downhaul
At its simplest the tack downhaul is a line attached to the mast thwart, rove through an eye
(or fitting) at the tack and returning to a cleat or belaying pin. I needed to retain the ability to
adjust the downhaul at the mast (crewed) and also from the steering position if single handed.
The lanyard has a stainless ring spliced into one end and the other end is lead through a block
attached to the mast, up through a second block which is hooked to the boom, travels down
through a tubular jamming cleat and is finished with a figure of eight.
Stainless ring and carbine hook.
The crew can adjust the downhaul simply by
utilising the tubular jammer. The stainless
steel ring at the other end of the line comes
up against the lower block.
Without a crew a control line is attached to
the stainless ring with small carbine hook and
is lead back to a cleat at the after end of the
centreboard case.
Lower block
Under certain conditions it needs quite a lot
of force to reduce the creases in the main
using this downhaul and the 2:1 mechanical
advantage is only just enough to make it easy
to operate. A cascade system with a block
replacing the carbine hook makes sense and
would give a 4:1 purchase.
Jamming cleat
2
Furling gear
Furling gear is a complication and something else to go wrong but it’s just so convenient I
wouldn’t want to be without it now.
There is another benefit apart from being able to furl the jib. If you can remove the original
forestay then it becomes so much easier when you tack as you don’t have to drag the jib
around the forestay.
The Dabber, in it’s original form, has a forestay terminating at the stem head and a bowsprit
with no bobstay. To set up furling gear and not to use the luff wire in the jib as a forestay
seemed a bit silly so a bobstay was a must. There was not a lot of choice in attachment points
with the sole option being the towing eye. In my boat this eye is 40 year old and made of
brass. It needed checking. (see later)
The bowsprit
The Dabber jib came with a loose eye at one end of the luff wire which looped over the end
of the bowsprit. There is nothing wrong with this and the original bowsprit would do the
job admirably but I decided to make a new bowsprit to incorporate a proper
cranse iron (mast band) to attach the rigging.
More
Beautiful
bronze.
I think the truth is that I liked the idea of laminating two
different coloured woods. Some of the bits and
pieces on boats are a joy to make and are
lovely to look at. Having said that, it
was a bad design and could
really do with being
replaced.
The
bowsprit
was laminated
using two pieces
of softwood and one of
mahogany. Moving the
forestay to the end of the
bowsprit, and providing a bobstay,
changes the loading on the bowsprit from
bending to compression. This means that the
tension in the rigging pushes the bowsprit towards
the stern and this force is transmitted to the mast thwart
via a wooden cleat screwed to the thwart. I didn’t think that
this was up to the job so replaced the cleat with a more substantial
version which I modified to act
as a mast crutch when trailing.
It was a real pleasure
to work with teak again..
3
Setting up the furling gear required:
• A wire bobstay from the towing eye to the end of the bowsprit. This is a length of 3mm
stainless wire with a snap shackle at one end and a bottle screw at the other.
It is important to realise that the rigging screw is only to adjust the length of the bobstay
and definitely not to tension the forestay.
• A furling drum attached to the end of the bowsprit.
The drum is attached directly to the cranse iron.
• A new forestay (luff wire) in the jib.
I used the same sized wire as I used for the bobstay.
• A furling line running back to a cleat amidships.
• A new jib halyard.
There are so many ways to rig the halyard, all with their own disadvantages, but I settled
for the simplest. It’s a three fold purchase with a fiddle block attached to the mast head
and rigged with braided line (three strand rope twisted too readily) leading down to the
belaying pin.
I’d be reluctant to use a system whereby the standing part, and the fall, terminate on the
mast thwart; it’s only held down by two 1/4” brass bolts per side.
Bearings
I did have serious problems with furling drum
and top swivel bearings in two manufacturers
products. In the end I had to replace the balls
in the drum with 4 mm stainless balls and
replace complete bearings in the swivel with
some intended for use in robotics.
Rigging tension
I didn’t want anything to break so some measurements and calculations were called for.
“Sweating” a rope using a belaying pin can be a very effective means of tensioning a rope; I
needed to find out just how effective.
Using a snatch block at the mast head and another one at the end of the bowsprit I was able
to lift 110 ponds below the end of the bowsprit without too much effort and without
assistance from a block and tackle. Given that the jib halyard was a 3:1 purchase I would be
able to tension the forestay to something like 330 pounds. (less with friction losses)
The geometry of the forestay, bowsprit and bobstay means that the tension in the bobstay
will be around 1.8 that of the forestay. This gives a bobstay tension of around 600 lbs. This is
within the SWL of the individual components but is still a lot of tension. A halyard with a 2:1
purchase would set up the rigging tension nicely but you can be a lot more precise with a
more powerful tackle as long as you are aware of the power.
4
Mast head
The Dabber came with what I assume is its original masthead fitting. This was a stainless
steel ring resting on a shoulder cut around the top of the mast and retained by a rather large
brass split pin. Wires were spliced directly onto the ring which had, over time, mangled the
top few inches of the mast.
There was no alternative but to scarf in a new top to the mast and, while I was at it, I fitted
another bronze mast band from Classic Marine. Bronze is such a lovely material that I’m
going to buy another one to keep on the kitchen table and admire.
Shrouds
The shrouds were originally attached to the deadeyes with a lashing; a method which has a
lot going for it.
Advantages of a lashing:
• Ca n be released easily and progressively while under load.
• Can be re-secured whilst under (some) load.
• The condition is obvious at a glance.
• It will fail gently and with some warning.
(rigging goes slack)
• It is quick and easy to replace.
Disadvantage of a lashing:
• Takes 30 seconds to secure and I’m lazy.
(especially when I’m contemplating repetitive tasks)
5
Because laziness rules, I’ve replaced the lashing with assorted stainless steel hardware.
Advantages of the stainless solution:
• Quick.
• Tension is pre-set.
Disadvantages of the stainless solution:
• Many parts, some of them moving.
• The condition is not obvious.
• It will fail with an unheralded bang.
However, the Dabber’s sail area is small and the mast
step/mast thwart is sufficiently robust such that if a
shroud parted I’m fairly sure that there would be
enough time to take the strain off the rig (tack or come
head to wind etc.) before any damage occurred.
The existing dead eyes were replaced with
RWO U Bolts (Part Number: RW-R2962)
It’s not the saving of 90 seconds when attaching the rigging that is important, it’s the
cumulative effect of many time saving modifications which means I’m quick and efficient
when rigging, launching and recovering the boat. This becomes even more desirable when
the slipway is busy.
I even use a snap shackle on main halyard – I can’t defend it but it ain’t half convenient.
Towing Eye (see also Repairs and maintenance in Part 2)
The towing eye has a hard life; it holds the rigging taut at sea and regularly hauls the boat
bodily up onto the trailer from a slipway with an 8:1 slope. It needs to be in good condition.
I was informed that the nuts to which the through bolts are attached would be encapsulated in
the laminate. As I unscrewed the first bolt, the sound of something dropping inside the hull
gave the lie to that. A Dabber, mine at least, has a part bulkhead just for’d of the mast
enclosing a compartment containing 2 1/4 cu ft of polystyrene buoyancy wrapped in plastic.
I’d known this beforehand as a small number of polystyrene beads occasionally floated
through the bilges but I hadn’t really wanted to get intimate with it all. No choice now.
I cut the polythene and retrieved the polystyrene through the gaps either side of the bulkhead
and hosed the bits remaining back into the bilges. The nuts were duly retrieved and a thick
brass plate was drilled and tapped to replace them.
What to replace the buoyancy with? I settled on one litre plastic bottles (not expensive if you
buy in bulk) and it took 68 to fill up the space. I made two part bulkheads out of ply which
go nearly out to the hull and keep the bottles in. They have shock cord loops attached which
hold my 2 litre fuel containers well out of the way and securely upright.
6
Trailers
I’ve been towing trailers for longer than I can remember and currently have four.
It seems to me that trailers cause more annoyance and inconvenience than anything else in
the boating world. The only things that come close are marine fouling and outboard motors.
This is not surprising when you consider that moving parts regularly operate in corrosive salt
water without adequate protection. Linkages and pivots seize and corrode. Wheel hubs get
warm when on the road and are then submerged in cold water with the resultant contraction
sucking water into the hub. Trailers need regular and systematic maintenance.
The only parts of my trailer in the water when launching or recovering the Dabber are the
tyres. However, it’ll still be a wet boat depositing sea water over everything.
Just launched or ready for recovery – The winch strap support is a piece of alkathene pipe.
Acetal rollers (the white rollers in the photograph)
The one and only “wow” moment that occurred during my work on the Dabber was after I
changed the aft keel roller from rubber to acetal. (Acetal is a hard material similar to nylon)
Winching the boat onto the trailer instantly became so much easier. I did add a second roller
later and bought them from versatilemarine.co.uk in Cornwall.
I had no idea that so much friction was caused when pulling a heavy boat like the Dabber
over the original rubber rollers.
Winch strap holder
A length of plastic water pipe located on a short stub at the rear of the trailer does two jobs. I
clip the winch strap hook to the top which keeps the strap clear of everything and within easy
reach when hooking on. I can also see it through the back window of the car as I reverse onto
the ramp. When not in use it is clipped to the trailer.
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Hogging
Even an often used “trailer sailer” probably spends 95% of its life sitting on the trailer and I
know that it is true of mine. If I decided to store the Dabber off the trailer for 95% of its life,
I would set up multiple wooden blocks for the keel using a line to level them. I certainly
wouldn’t support the boat on one block in the middle – yet leaving it on my trailer is the
equivalent of doing just that.
I use a popular make of boat trailer for the Dabber which has a single spine of 50 mm box
section steel and bears the weight of the boat on three keel rollers. If the tops of the rollers
are in line when the trailer is empty, and you then load a boat with a straight keel, there is
very little weight taken by the forward or aft rollers because of the flexibility of the trailer
chassis. You can test this easily; tie the bow of the boat down to the trailer, move aft and
push down the back of the trailer until you can just turn the aft roller. It won’t take a lot of
effort.
I did some tests, measurements and some Q&D calculations. In order to pre-load the trailer I
needed to raise the fore and aft keel rollers by 3/4 inch. Now, when the boat is on the trailer,
it is evenly supported at three points. (I did add an extra roller so that’ll be four then!)
Having said all that, I’m sure my Dabber has spent most of its 40 years supported only on the
centre roller of whichever trailer it’s been living on. In spite of that I cannot detect any
hogging or sagging but I still feel happier having the boat properly supported. It probably
also contributes to a smoother suspension.
The foregoing applies only to my boat on my trailer. Other designs will be different.
Hubs
It’s a rare occasion in engineering that require hubs or
bearings to be completely filled with grease but I can
make a good case for this being applied to boat trailer
hubs.
• When assembling a hub I make every effort to fill all
available space with good quality grease.
• I vent the hub via a short tube. Any water forced into
the tube will be ejected from the tube when the hub is
topped up (frequently) with the grease gun.
Tyre pressures
Schrader stem with vented cap.
I have never been able to find an authoritative source for trailer tyre pressures that I trust.
The ability to “copy and paste” has diluted the general level of accuracy on the internet to a
low level. It seems to me that about one quarter of the information on the web is true, one
quarter is incomplete or misleading, one quarter is wrong and one quarter is dangerous.
As a case in point, I can find tyre pressure recommendations for 10” trailer tyres which range
from 30 to 60 psi. I contacted two manufacturers of popular boat trailers requesting
information, one replied saying that tyre pressures depended upon the load carried but
provided no further details and the other company gave me a single psi figure for all loads.
This is daft. Until I get some information I trust I will continue to use 30 psi for all my
trailers as I have for many years. I’ve had zero problems with uneven wear and the tyres
never even get warm so it can’t be too far out.
8
Suspension
Most boat trailers incorporate a rubber suspension system without any sensible damping
system. How these ever got type approval for use on the roads amazes me. The suspension is
so hard that a boat can be damaged if trailed a long way. It’s worse with a lighter boat but
even with the suspension matched to the load, the boat gets hammered.
I have one trailer with proper springing and hydraulic dampers. The movement of my Laser
(very light) is so smooth and gentle on this trailer compared to its harsh ride on its dedicated
rubber suspension equivalent. These trailers are convenient though and the parts are a lot
more salt water resistant than trailers with real suspension.
It has occurred to me that changing tyre pressures might adjust the contribution the tyres
make to the suspension. I’ve tried this and have come to the (subjective) opinion that you
have to reduce the tyre pressures to the point where they look soft before the ride seems
softer. So I’ll stick with 30 psi.
Light board
The ultimate laziness – I’ve mounted the light
board above the transom with wooden brackets.
This now means I can leave the rudder and tiller
on the boat all the time.
Fits in the holes
designed for the horse.
What I haven’t done
I don’t name inanimate objects so the Dabber is nameless. It is also an “it” and only on very
rare occasions does “it” become a “she”.
I’m very grateful to the previous owners of this boat for not leaving holes or marks from any
modifications they made and I’ve done the same. Everything I have done to the hull could be
returned to the original configuration without leaving an obvious trace. The mast and the oars
have been repaired and modified though but I can see no way around this.
I’ve completely neglected the cosmetics apart from varnishing the oars and spars. The gel
coat is unpolished, there is antifouling which should be removed and the for’d end of the
keel could do with fairing and painting. The boat would also benefit from larger section bilge
keels.
Will I ever do these jobs? Probably not. This Dabber will be well maintained, with no
expense spared, and will live most of its life ashore and under cover. In any case, I’m more
interested in how it performs than what it looks like.
The next thing should probably be some new sails.
What I have done and wished I hadn’t
Rudder blade 1
The rudder blade is such a strange shape that when I created the aerofoil section I did it
backwards. I ended up with a sharp leading edge and a blunt trailing edge which meant that
going astern, intentionally or unintentionally, the rudder was very efficient. I could only live
with this for a while and ended up with a semi-symmetrical section. Only the fishes and I
know this though.
9
Rudder blade 2
The first rudder blade was
too small. It looked too small
in the drawings, in the
photographs and on the boat.
Why didn’t it register?
Tiller extension attachment
There is a silly piece of oak
bolted to the end of the tiller
to which the tiller extension joint is attached. To this day I don’t know why I
made it although the extension itself is great and can be stowed, extended
horizontally and also used as a normal extension.
Boom size
The vertical section of the original boom was much too small. I normally
“over engineer” things I make so must have over-compensated.
Kicking strap
I tried one – I don’t know why.
Bowsprit (The worst)
When I made a new bowsprit I incorporated a shoulder which located
against the stemhead fitting. This has had three effects:
• It was a lot more difficult to make.
• The bowsprit won’t slide aft for stowage.
• The change of section increases the chance of it breaking at exactly
the wrong place.
Keep it simple
All of these modifications I’ve made to my Dabber are done for one reason and one reason
only and that is to increase my enjoyment while sailing the boat. They are specifically
relevant to me and to where and when I sail.
If I was coasting in the Dabber then some of these modifications would be scrapped. I neither
need nor want anything unnecessarily complicated at sea.
• The rudder and tiller would revert to the original design. It’s two pieces of wood and a
bolt and I don’t need a lifting rudder on a coastal passage.
• The outboard would be lashed alongside the centreboard case. (or left ashore)
• The rigging would be tensioned using lashings.
• The original forestay would be re-instated and the furling gear removed
On the other hand nothing would induce me to return to the original mainsheet so the boom
would stay.
10
Ready to roll.
If one person has found any of this useful then it was worth doing.
If I can add any detail or help anyone then please contact me.
I’d welcome constructive and reasoned comments.
Part 1 Rudders
Part 2 Tillers and Booms
David Tornberg – [email protected]
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