I suppose the original windscreens
might have been glass, laminated or not, but I don't want to take
authenticity that far. I have ordered a pair of acrylic screens, which
have good UV resistance but only fair scratch protection. They are not
as expensive as polycarbonate, and they should do the job. I'm not
exactly sure just what that job is, as the front seat occupants' heads
are at level way over the top of the screens, and the boat is hardly
going to be fast enough to create any sort of slipstream over them.
Perhaps they merely serve to keep any splashes out of the cockpit.
But one thing they should definitely not be, in my view, is prefabricated, bought and dropped on. These aluminium framed jobs look so out of place on the woodwork of a slipper launch, that I cannot imagine what possible advantage they could offer, except convenience. Better to go without a screen altogether than to get a bought one.
The "glass" will have to be sealed into the frame, not to secure them particularly, but to keep water away from the grooves which house them. Silicone sealant should do the job, and will stop any rattling too. I have been protecting the windscreen frames up to this point by having some ply faux screens in them, and they have now been removed to act as templates for the acrylic cutter.
The acrylic windscreens. They are just a little easy to scratch, so may have to be replaced in due course.
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151. The Skeg
152. Hatch Surrounds
153. Converting the Hatch Vents to Dorades
But one thing they should definitely not be, in my view, is prefabricated, bought and dropped on. These aluminium framed jobs look so out of place on the woodwork of a slipper launch, that I cannot imagine what possible advantage they could offer, except convenience. Better to go without a screen altogether than to get a bought one.
The "glass" will have to be sealed into the frame, not to secure them particularly, but to keep water away from the grooves which house them. Silicone sealant should do the job, and will stop any rattling too. I have been protecting the windscreen frames up to this point by having some ply faux screens in them, and they have now been removed to act as templates for the acrylic cutter.
The acrylic windscreens. They are just a little easy to scratch, so may have to be replaced in due course.
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151. The Skeg
Taking the
weight of the rudder, theoretically, and protecting it from grounding
or other misadventures, is the skeg. It is specified to be galvanised
iron, bolted into the bottom of the keel, and housing the bearing for
the rudder stock at its bottom end. I am replacing the galvanised with
stainless steel, but otherwise it will be as specified. A 10 mm. deep
recess has already been cut into the bottom of the keel to house the
skeg, although it could easily have been merely bolted on directly.
However, the actual placement of the part will dictate how it will be
attached. If the recess is to be functional it will have to lie at
exact right angles to the rudder stock. Just looking at it I feel
that the angle is slightly off square, and that more of the keel
will need to be shaved away. That means jacking up the back of the boat
and working underneath it.
The boat has to be jacked up anyway, to extract the rudder. It still has to have a flat ground out of the stock to accept the screws from the tiller. I need about one metre of clearance to extract the rudder. At the moment I have about 400 mm. Obviously a simple car jack is not going to be sufficient, and I don't trust the strength of the ceiling beams in my garage to take the weight of the boat on blocks and tackles. A bigger jack will have to be hired, and the boat then packed up in its raised aft position to make it safe to work under.
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The boat has to be jacked up anyway, to extract the rudder. It still has to have a flat ground out of the stock to accept the screws from the tiller. I need about one metre of clearance to extract the rudder. At the moment I have about 400 mm. Obviously a simple car jack is not going to be sufficient, and I don't trust the strength of the ceiling beams in my garage to take the weight of the boat on blocks and tackles. A bigger jack will have to be hired, and the boat then packed up in its raised aft position to make it safe to work under.
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152. Hatch Surrounds
The hinges
have been settled on already, so the remaining hatch surrounds have to
match them. I just have to get some stainless steel sheet, of the same
thickness as the hinge leaves, cut to size and bored for screw holes.
The surrounds will help to keep water out of the gap between the hatch
covers and the rest of the deck. Apart from that they appear to serve
no purpose other than to lacerate any unwary body parts which come into
contact with them.
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Top of Page
153. Converting the Hatch Vents to Dorades
The
electric motor really does not need much in the way of air circulation,
but the hatches over the motor compartment have been given cowl vents
for two reasons: the authentic look, and, more importantly, the
establishment of an air intake for the sub-sole ventilation system, and
the retro-lagging space circulation. These latter two both depend on a
decent intake of air into the motor compartment.
The trouble is that the vents in the motor compartment hatches overlie the electrics, and any water entering through them could be dangerous. For that reason the hatches had drained gutters, and now a method has to be devised to keep the vent openings dry.
Luckily the problem has been encountered before, and the system devised for the yacht, Dorade, has been adopted as gospel. The idea is simple. The vent opens into a dammed compartment which is scuppered to drain any water from it. The air circulates over the top of the dam wall into a dry compartment, which communicates with the cabin or cockpit for which the air is intended. The original dorade vent was located on a box sitting on top of the deck, but that is not suitable for a slipper launch. Instead, the entire hatch cover can be converted into a dorade, which will, therefore, sit below deck level.
This would have been a lot easier if it had been constructed before the subdeck had been attached to the hatch covers, although that would have made the attachment of the vents themselves more difficult. (I am using small bolts, washers and nuts). We need a compartment bottom, or floor, running from the front of the hatch cover to the dam wall, and a scupper from the most dependent part of the structure into a drain tube, which can conveniently communicate with the drain tube from the hatch drip channel. The tubing has to be sufficiently flexible and long to allow the hatch cover to be opened. The dam wall has to be astern of the vent opening in the deck, and sufficiently tall to prevent water from splashing back over it into the motor compartment, but sufficiently low so as not to impede the free circulation of air over it. The whole structure will have to be waterproof in case of imperfect drainage and subsequent rot problems, but in essence it is a simple task which will make the electrics much more secure.
The most dependent part is the forward, outer corner of the hatch cover, which is where the gutter is most dependent too. So, on each side of the boat two lengths of tubing, one from the dorade and the other from the gutter, will meet via a Y connector to emerge into a common tube, which can then empty into a reservoir, or the bilge, or overboard with a through-hull. It am not expecting large volumes of water to come down these tubes, so I think a through-hull is overdoing it. And I would rather not have any water in the bilge if possible, so that leaves the reservoir. The one container could be used to drain both sides, and could conveniently be located out of the way in the fuel compartment, as long as it is easily reached without me having to get right into the motor compartment.
Of course, the whole dam wall concept is not vital, provided you use a raised exit vent from a closed dorade instead. A simple solution is a flanged PVC pipe fixture, in this case a roof gutter outlet.
This can be run up through the dorade's base into the cavity. The base has to be extended to enclose the entire cavity, which makes that space inaccessible, but is is certainly well ventilated!
The base can be made removable as long as it is watertight. This can be achieved with mastic or silicone around its inside perimeter where it is screwed to the hatch cover. That way, if it is ever necessary to remove the cowls, which are bolted on, they can be reached. (I could have used screws instead of bolts, but because the cowls will be used as handles to open the hatch covers I felt that the security of bolts in ply was better).
Some ledger strips are screwed to the inside of the hatch covers, leaving a gap where the scupper will pass through the floor of the vent.
Ledger strips for the vent floor.
The
scuppers for these dorades have to sit right at the outer forward
corner of the structures, so as not to allow water to pool undrained.
They have only 6 mm. of ply to hold them in place, and I felt that that
would not be sufficient as the hatches will be opened and closed a fair
bit. The solution was to build up a shim on the bottom of the dorade,
at the location of the scuppers, and to drill through both the shim
and the dorade floor. The holes are just big enough to allow 5/16"
threaded ports (breather hose take-offs) to be let into them, and the
shims are thick enough
that the top of the threaded segment lies flush with the top of the
floor, or a little below that level. The
rest of the port consists of a central hex nut for tightening, and a
barbed pipe onto which the tubing can be connected. The shim is made
of solid wood rather than ply, to give the thread some bite, and the
whole lot is epoxied together.
The dorade scupper.
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154. Caulking the Decks
155. Coaming Beading
156. The Propeller Shaft Anode
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Problems shows higher resolution shots as well.
The trouble is that the vents in the motor compartment hatches overlie the electrics, and any water entering through them could be dangerous. For that reason the hatches had drained gutters, and now a method has to be devised to keep the vent openings dry.
Luckily the problem has been encountered before, and the system devised for the yacht, Dorade, has been adopted as gospel. The idea is simple. The vent opens into a dammed compartment which is scuppered to drain any water from it. The air circulates over the top of the dam wall into a dry compartment, which communicates with the cabin or cockpit for which the air is intended. The original dorade vent was located on a box sitting on top of the deck, but that is not suitable for a slipper launch. Instead, the entire hatch cover can be converted into a dorade, which will, therefore, sit below deck level.
This would have been a lot easier if it had been constructed before the subdeck had been attached to the hatch covers, although that would have made the attachment of the vents themselves more difficult. (I am using small bolts, washers and nuts). We need a compartment bottom, or floor, running from the front of the hatch cover to the dam wall, and a scupper from the most dependent part of the structure into a drain tube, which can conveniently communicate with the drain tube from the hatch drip channel. The tubing has to be sufficiently flexible and long to allow the hatch cover to be opened. The dam wall has to be astern of the vent opening in the deck, and sufficiently tall to prevent water from splashing back over it into the motor compartment, but sufficiently low so as not to impede the free circulation of air over it. The whole structure will have to be waterproof in case of imperfect drainage and subsequent rot problems, but in essence it is a simple task which will make the electrics much more secure.
The most dependent part is the forward, outer corner of the hatch cover, which is where the gutter is most dependent too. So, on each side of the boat two lengths of tubing, one from the dorade and the other from the gutter, will meet via a Y connector to emerge into a common tube, which can then empty into a reservoir, or the bilge, or overboard with a through-hull. It am not expecting large volumes of water to come down these tubes, so I think a through-hull is overdoing it. And I would rather not have any water in the bilge if possible, so that leaves the reservoir. The one container could be used to drain both sides, and could conveniently be located out of the way in the fuel compartment, as long as it is easily reached without me having to get right into the motor compartment.
Of course, the whole dam wall concept is not vital, provided you use a raised exit vent from a closed dorade instead. A simple solution is a flanged PVC pipe fixture, in this case a roof gutter outlet.
The
flanged outlet vent.
This can be run up through the dorade's base into the cavity. The base has to be extended to enclose the entire cavity, which makes that space inaccessible, but is is certainly well ventilated!
The base can be made removable as long as it is watertight. This can be achieved with mastic or silicone around its inside perimeter where it is screwed to the hatch cover. That way, if it is ever necessary to remove the cowls, which are bolted on, they can be reached. (I could have used screws instead of bolts, but because the cowls will be used as handles to open the hatch covers I felt that the security of bolts in ply was better).
Some ledger strips are screwed to the inside of the hatch covers, leaving a gap where the scupper will pass through the floor of the vent.
A floor of 6 mm. ply
is fitted, and will eventually be screwed to the ledgers. Holes are cut
for the PVC downpipe and expanded for a snug fit only, as it has to be
watertight.
The PVC downpipe is fitted.
The PVC downpipe is fitted.
Then the
floor is dropped onto the ledgers, and a completely sealed compartment
is achieved, which will allow the flow of air from the cowl to enter
the motor compartment. As yet there is no hole cut in the hatch cover
on the top, because I want to do that after the deck has been caulked
and varnished.
The vent floor in place on the starboard hatch cover (left), and the port one seen relative to the cowl (right).
The vent floor in place on the starboard hatch cover (left), and the port one seen relative to the cowl (right).
The dorade scupper.
To
begin with, the nipple of the structure has to be removed. That is
easily achieved with a hacksaw. The screw thread on the one I have
chosen is 1/2", so there are no conveniently sized ordinary drills
which can cut a hole just the right size. A set of brad points gave the
right one, a 15/32" bit, which is just tight enough to allow the thread
to be driven home without splitting the wood. Even so, I took the
precaution of drilling it away from an edge. It now has to be cut out
and fitted up against the dorade's floor. With the floor there is no
option to
drill away from the edge, because the scupper has to sit right at the
corner. So, I use 1/2" bit and left the thread glide through that
part. It will be glued in later anyway.
The nipple has been chopped off and the thread run through the wood which will be used as the shim (left), underneath view (right).
The finished scupper in the dorade's floor.
The nipple has been chopped off and the thread run through the wood which will be used as the shim (left), underneath view (right).
The
shim was cut into a disc and clamped to the dorade floor with the
scupper in situ while the overhanging edges were sawn off. The final
arrangement leaves the top of the scupper a little shy of the top of
the floor, which is perfect for drainage.
The finished scupper in the dorade's floor.
With
the tubing attached there has to be a fair bit of length left for the
hatches to open. This is now how they will remain until the time comes
to apply the finish and stick the floors on semi-permanently.
154. Caulking the Decks
The major job for
this month is supposed to be the caulking, but the continuing hassles
from the gunwale have infringed on that a bit. Now that the gunwale
seems to be under control, the deck is finally ready for its finishing
touches. Firstly it is all sanded smooth to about 240 grit, paying
particular attention to the strips next to the windscreen and the rear
coaming. It is here where any irregularities will show up as gaps
between the strips and the beading.
Then the grooves between the decking strips have to be cleared out of as much epoxy and grit as possible. There is a useful tool for this, which is meant for scraping grout out from between tiles. The blade is serrated, and it fits perfectly between the planks.
Then the planks themselves have to be protected from the caulking compound. After my experience with it on the rubbing strake, I have no confidence in masking tape alone, so I propose to apply a layer of varnish to the planks, which will be lost again when the Sikaflex is sanded down
I have to admit to having second thoughts about using Sikaflex 291 as a caulking compound. While is was successfully, although messily, employed in attaching the rubbing strake to the hull, I have some misgivings about using it where it needs to be sanded. Because, although the company literature advertises that it is sandable, the stuff which has been sitting in the nozzle of the caulking gun, over the weeks since the strake was put on, is still completely rubbery, and impossible to sand. If that happens on the deck it will be a major problem to sort out.
So, the first step here is to do a trial caulking between some left over decking strips on plywood. At 5 mm. thick the Sikaflex should only take two or three days to cure. After that I will try sanding it and see what happens. For reasons I have already discussed in previous months, I do not want to use the graphite thickened epoxy which is recommended in the plans for this boat. The mess would be horrific, and it would very likely run down on the rear deck because of its slope. But something which sets solidly enough to be able to be sanded down with the rest of the decking is vital to a good looking finish.
For the trial, half the decking is covered with masking tape, and half not, to see if that helps at all.
Then the grooves between the decking strips have to be cleared out of as much epoxy and grit as possible. There is a useful tool for this, which is meant for scraping grout out from between tiles. The blade is serrated, and it fits perfectly between the planks.
Then the planks themselves have to be protected from the caulking compound. After my experience with it on the rubbing strake, I have no confidence in masking tape alone, so I propose to apply a layer of varnish to the planks, which will be lost again when the Sikaflex is sanded down
I have to admit to having second thoughts about using Sikaflex 291 as a caulking compound. While is was successfully, although messily, employed in attaching the rubbing strake to the hull, I have some misgivings about using it where it needs to be sanded. Because, although the company literature advertises that it is sandable, the stuff which has been sitting in the nozzle of the caulking gun, over the weeks since the strake was put on, is still completely rubbery, and impossible to sand. If that happens on the deck it will be a major problem to sort out.
So, the first step here is to do a trial caulking between some left over decking strips on plywood. At 5 mm. thick the Sikaflex should only take two or three days to cure. After that I will try sanding it and see what happens. For reasons I have already discussed in previous months, I do not want to use the graphite thickened epoxy which is recommended in the plans for this boat. The mess would be horrific, and it would very likely run down on the rear deck because of its slope. But something which sets solidly enough to be able to be sanded down with the rest of the decking is vital to a good looking finish.
For the trial, half the decking is covered with masking tape, and half not, to see if that helps at all.
The new,
cartridge-dispensed, thickened epoxy from WEST, called Six 10, would
have been
ideal for the job if it had been available in black, or brown, or even
white. But it is not, yet.
If the
decision is to go with the Sikaflex, it will need to go over a primed
surface, not only because of all the epoxy which coats the wood, but
also because of the waxy nature of the White Beech, which makes
adhesion quite unreliable. That idea has
been reinforced by the test strip above. While shaving off the excess
Sikaflex I
noticed that a small portion of it popped out altogether, because there
was poor grip between it and the bare wood. Apart from
that, it behaved well enough. Hand sanding produced a little black dust
which got into the grain of the White Beech, but it was easily blown
out. Sanding with a random orbital sander attached to a vacuum produced
no residual dust at all. The masking tape was totally useless. It just
peeled out from under the bead of Sikaflex. With a coat of finish
applied to each decking strip an idea of the final look is appreciated.
However, even after three days the varnish on the Sikaflex has not
dried, whereas it is bone dry on the wood. That may be because the
Sikaflex itself was not fully hardened, so it should probably be left
for a week or so before overcoating.
The result of the caulking trial. Note the missing segment at bottom (right).
The result of the caulking trial. Note the missing segment at bottom (right).
The first area which is
varnished is the covering board on both sides. In order to blend the
mahogany in with the rest of the boat, I am using the same Cetol I used
in the cockpit, but this time more as a stain than a finish in its own
right, because it will be varnished over the top later. I know this
defeats the purpose of Cetol a bit, designed as it is to be easily
repairable, but it is the only way I can get any uniformity in the wood
colour. At the same time as I give the covering boards a coat, I put
one more layer of green paint on the top strake, which has suffered a
little from bumps since it was done previously.
The port covering board takes a coat of Cetol.
The port covering board takes a coat of Cetol.
The covering boards
need a second coat because they are still quite dry and patchy after
just one. That would not be effective in repelling epoxy from the
gunwale when it is glued on.
After one coat of Cetol.
After one coat of Cetol.
The decking planks
also need coating, and after some varnish on the White Beech, they are
beginning to take on a mellower look than they have had up to now. I
actually like the white look you can achieve on pale wood with lacquer,
but
without spray equipment, or the area to use it, I have to settle for
the
slight yellowing you get with the Monocel.
All the wood now
needs a second coat before the caulking. A light sanding is in order at
this stage because of the raised grain. Then, masking tape along side
the grooves, even although I have no faith in it. It just may help to
preserve enough of the sacrificial varnish that I do not have to sand
it back to the bare wood and start again.
Here, the gunwale is temporarily returned to the hull so that its lower edge can be marked
and masked on the green top strake. That will help keep the epoxy off it when the gunwale
is glued on.
After a second coat
on the covering boards their gloss level makes the rubbing strake look
very dull, so it is given a coat too. I expect that it will last about
five minutes as the strakes serve their purpose, but it will make for a
good looking launch day.
Here, the gunwale is temporarily returned to the hull so that its lower edge can be marked
and masked on the green top strake. That will help keep the epoxy off it when the gunwale
is glued on.
The
second coat of varnish begins to bring out the figure in the wood, and
then dries out to a lovely, soft, satin lustre. Once this has
hardened it is time to apply the caulking and glue on the gunwales.
After the second coat of varnish.
After the second coat of varnish.
One of the reasons for choosing
satin finish over gloss, apart from the fact that it looks better to my
eye, is that satin does not show up flaws as much. But even satin when
it is wet acts as a gloss, and reveals surface defects which are not
always apparent in the raw timber. In this case, the butt joint between
the side and foredeck covering boards proved to be a little depressed
below the surface. This was more noticeable on the port side than the
starboard. Having noticed it, I then had the choice of planing back the
boards in front and behind, in the hope of evening it out, (and
repeating the miracle on the other side), or trying to elevate the
depression somehow. In this case there was only a fraction of a
millimetre in it, but enough to show as a defect in the right light.
But, since there are to be at least four coats of varnish, and probably
more, applied here, there is a chance to fill the hole with varnish by
pre-coating the area a few times, and sanding back each coat, before
the main coats are applied.
That is what I decided to try, and even after one pre-coat it seemed to be having a good effect.
Meanwhile, the first attempts at caulking are begun, on the rear hatch cover firstly. The grooves are cleaned out and painted with primer, which is allowed to go off for 1 hour. Then, the plank edges are protected with making tape, and the caulking compound is pumped into the groove with a caulking gun. I am trying the technique where you scrape the still wet caulking over the top of the masking tape with a chisel, in an attempt to level it with the wood.
Priming the grooves (left), and applying a bead of Sikaflex to the first groove (right).
That is what I decided to try, and even after one pre-coat it seemed to be having a good effect.
Meanwhile, the first attempts at caulking are begun, on the rear hatch cover firstly. The grooves are cleaned out and painted with primer, which is allowed to go off for 1 hour. Then, the plank edges are protected with making tape, and the caulking compound is pumped into the groove with a caulking gun. I am trying the technique where you scrape the still wet caulking over the top of the masking tape with a chisel, in an attempt to level it with the wood.
Priming the grooves (left), and applying a bead of Sikaflex to the first groove (right).
The chisel spreads
the excess caulk onto the masking tape, which is then immediately
peeled off, while the caulk is still wet.
After spreading with the chisel (left), and removal of the tape (right).
Initially the result is good, but after a little while the caulking begins to sink down into the groove a little, below the surface of the timber. So the bead is topped up with another one laid on top, and the process repeated. The result is pretty much the same, some uneven depression of the bead into the groove.
The completed first caulk.
After spreading with the chisel (left), and removal of the tape (right).
Initially the result is good, but after a little while the caulking begins to sink down into the groove a little, below the surface of the timber. So the bead is topped up with another one laid on top, and the process repeated. The result is pretty much the same, some uneven depression of the bead into the groove.
The completed first caulk.
From
a distance the appearance is fine, but close up there is definite
unevenness in the caulk line. Moreover, there will be 10% shrinkage as
it dries, so the line will become even more depressed. There are three
possible solutions here. One is to accept it and just varnish over.
Two, is to sand everything back to the caulk level. Three is to build
up the caulk line with a second bead, after the first has begun to set.
The third option appealed most, although I had no idea whether it would work, and whether a new bead of Sikaflex would stick to an older one. I thought it would not after the old one had completely dried, but that while it was setting up there may be a chance. Don't try it. The mess was worse than the worst I ever got into with epoxy, and this black stuff won't come off your hands short of scouring it off.
I think I will settle for the depressed line for the time being.
On the next set of hatch covers, the forward ones, I changed the technique a bit. Rather than trying to skim of the excess Sikaflex with a chisel I left the bead sitting proud of the timber. There was enough so that it would still sit proud even after the 10% shrinkage. This will need to be trimmed and sanded, but that is what I had in mind in the beginning, and I suspect that it will be preferable to the chisel method in the long run.
However, in the end the best method was to use the chisel for one pass, let it dry, apply a second bead and immediately scrape it flush again, and then sand it. The slicing off of excess caulking required for method two was too hazardous to the timber.
While the hatch covers are drying for a few days, I can get out to D H Porters and order the skeg and hatch surrounds for fitting after the deck is finished. And, with the experimentation on the hatches over, I set out to do the decking proper.
Here, the first two gaps on the starboard have been filled with a single bead. A second will go on in a day's time.
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The third option appealed most, although I had no idea whether it would work, and whether a new bead of Sikaflex would stick to an older one. I thought it would not after the old one had completely dried, but that while it was setting up there may be a chance. Don't try it. The mess was worse than the worst I ever got into with epoxy, and this black stuff won't come off your hands short of scouring it off.
I think I will settle for the depressed line for the time being.
On the next set of hatch covers, the forward ones, I changed the technique a bit. Rather than trying to skim of the excess Sikaflex with a chisel I left the bead sitting proud of the timber. There was enough so that it would still sit proud even after the 10% shrinkage. This will need to be trimmed and sanded, but that is what I had in mind in the beginning, and I suspect that it will be preferable to the chisel method in the long run.
However, in the end the best method was to use the chisel for one pass, let it dry, apply a second bead and immediately scrape it flush again, and then sand it. The slicing off of excess caulking required for method two was too hazardous to the timber.
While the hatch covers are drying for a few days, I can get out to D H Porters and order the skeg and hatch surrounds for fitting after the deck is finished. And, with the experimentation on the hatches over, I set out to do the decking proper.
Here, the first two gaps on the starboard have been filled with a single bead. A second will go on in a day's time.
By
the way, I am already very glad that I decided to put a coat of finish
on the wood before attempting this. There have been numerous blotches
of caulking compound, and the wood has only been spared because of its
finish. If this were a proper traditional laid deck with 20 mm. strips
it would not matter so much, because it could all be sanded off, but
with only 5 mm. to play with I want to keep the sanding to a minimum.
With the caulking started and moving over towards the centre of the boat, I have taken the opportunity to attach the starboard gunwale permanently, and plug its screw holes. I had entertained the idea of using black plugs at one stage, but I thought that they would make it look like a perforated paper for tearing off, so I have used the same brown Merbau.
The gunwale is glued on and plugged.
With the caulking started and moving over towards the centre of the boat, I have taken the opportunity to attach the starboard gunwale permanently, and plug its screw holes. I had entertained the idea of using black plugs at one stage, but I thought that they would make it look like a perforated paper for tearing off, so I have used the same brown Merbau.
The gunwale is glued on and plugged.
The
presence of the gunwale makes it a lot safer to get up onto the deck;
safer for the deck rather than the climber, as the edge of the planking
is no longer vulnerable.
The rest of the job of caulking is going to be a series of first and second caulks, sanding back and revarnishing. It is a slow process, which will take up the rest of the month. By the end of it I hope to be very much better at using the caulking gun, because at the moment it seems you have to have the strength of Popeye to be able to squeeze the damned stuff out through the small hole in the nozzle, which is necessitated by it having to go into the 3 mm. gap.
The sanded areas have to be coated separately in Cetol for the Mahogany and Monocel for the White Beech. After that the Monocel goes all over, which makes the job a lot easier. The newly covered rear hatch cover, which now has its first coat of all-over Monocel, is taken outside for photographing. It shows the true colour better than the indoor shots.
On the foredeck, work is progressing with the caulking. The first four gaps are now filled. The forward hatch has also been all-over coated with Monocel, and the difference shows between it and the sacrificial coats on the rest of the deck.
When the caulking is finally finished, and the deck is fully varnished, the coamings and windscreen have to be beaded onto the deck and covering boards, and then the hardware can be fitted.
The rest of the job of caulking is going to be a series of first and second caulks, sanding back and revarnishing. It is a slow process, which will take up the rest of the month. By the end of it I hope to be very much better at using the caulking gun, because at the moment it seems you have to have the strength of Popeye to be able to squeeze the damned stuff out through the small hole in the nozzle, which is necessitated by it having to go into the 3 mm. gap.
The sanded areas have to be coated separately in Cetol for the Mahogany and Monocel for the White Beech. After that the Monocel goes all over, which makes the job a lot easier. The newly covered rear hatch cover, which now has its first coat of all-over Monocel, is taken outside for photographing. It shows the true colour better than the indoor shots.
The
newly coated rear deck cover.
On the foredeck, work is progressing with the caulking. The first four gaps are now filled. The forward hatch has also been all-over coated with Monocel, and the difference shows between it and the sacrificial coats on the rest of the deck.
However,
at this point I hit a snag. Just as occurred with the test strip, I
found that the varnish on top of the Sikaflex does not dry. Even after
a few days it is still sticky. Some helpful advice from a reader who
did a similar job with a deck alerted me to the need to overcoat the
Sikaflex with a primer before the varnish. The one he used is not
available here, but it is a low viscosity product, and
moisture cured just as the
Sikaflex itself is. It sets to a high gloss finish which accepts alkyd
varnish with no issues of compatability.
It occured to me that the Sika Primer 215 which I had been using may do the same thing, so another day was devoted to trying out the drying properties of a strip coated in it. If successful it would mean going over all the caulking with this primer before proceeding with the varnish. As luck would have it things worked perfectly. The varnish dried in the same time on the primed Sikaflex as on the wood . So every caulked gap will need priming. I wish I had shares in masking tape!
It occured to me that the Sika Primer 215 which I had been using may do the same thing, so another day was devoted to trying out the drying properties of a strip coated in it. If successful it would mean going over all the caulking with this primer before proceeding with the varnish. As luck would have it things worked perfectly. The varnish dried in the same time on the primed Sikaflex as on the wood . So every caulked gap will need priming. I wish I had shares in masking tape!
When the caulking is finally finished, and the deck is fully varnished, the coamings and windscreen have to be beaded onto the deck and covering boards, and then the hardware can be fitted.
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155. Coaming Beading
Finishing
off the decking means adding a bead around the entire deck up to the
coaming on three sides and the windscreen on the other. The dimensions
of the beading are not critical, as long as it does its job of keeping
water out from between the coaming/windscreen and the deck. However, at
the stern end of the cockpit, along the transverse coaming, and at the
rear end of the side coaming, there will be studs for the attachment of
the hood. The traditional boats appear to have simple posts. A toggle
arrangement would be more secure, but the dimensions of the toggle will
determine how much of the coaming I can afford to lose under the
beading. Also to be considered here is how close to the edge of the
hood the grommets can go which will encircle the toggles. It may be
that there is not enough coaming width, particularly at the rear where
it is only 30 mm., to accommodate both toggles and beading, in which
case the simple post fasteners will suffice.
The simple stud arrangement for hood fixation.
The simple stud arrangement for hood fixation.
I
presume that these devices are designed to mate with lift dot
fasteners. The studs are probably of this sort.
The
angle between the coaming/windscreen and the deck is constantly
changing, because of the camber of the deck, in the case of the
windscreen and rear coaming, and because of the changing slope of the
side coaming as it follows the inclination of the hull. So it is
necessary to cut the beading at an angle which is sufficiently obtuse
that the most obtuse part of each section is catered for. That means
that there will be small gaps between the middle of the beading and the
coaming/windscreen where the angles are more acute, but these will be
filled by epoxy.
Working out the compound angles for cutting these small parts to meet one another is hardly worth the effort. They will invariably be imprecise, and there is enough give in the beads to tolerate a bit of twist and bow. That will be needed anyway in areas like the apex of the windscreen central post, which has become a little rounded by sanding. A combination of bending the beading to fit as much as possible, and filling the remaining gaps with wood coloured epoxy should make for an acceptable joint.
A shallow bead of 5 mm. thickness allows room at the back for the hood, and is flexible enough to bend around some of the corners. At that thickness it can only be about 10 mm. wide, possibly less. It depends on how it looks. It also precludes using clamps to hold the beading in place, but instead it allows brads to be used. The brad holes will be filled with wood coloured glue afterwards, and will be virtually invisible.
Before setting out on the actual beading, I have done some experimentation with some scrap cut to approximate size. The most difficult part is the windscreen area, where the camber of the deck means that the bead has to bend backwards. Eventually I will be able to remove the windscreen and use the screen frame for clamping the beads in place, but temporarily I can push them in with brads.
A trial beading using scrap.
Using an offcut of the piece shown above I can work out where a similarly dimensioned piece on the side will intersect with it, and, therefore, the mitre angle can be demonstrated. This one, cut at 40°, is just about right.
The mitre joint.
After rounding the leading edges and adjusting the width to its best look and most manoeuvrable dimension, four pieces are cut and ready to go when the time comes. I will leave the mitre jointing until the beads are actually being glued down.
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Working out the compound angles for cutting these small parts to meet one another is hardly worth the effort. They will invariably be imprecise, and there is enough give in the beads to tolerate a bit of twist and bow. That will be needed anyway in areas like the apex of the windscreen central post, which has become a little rounded by sanding. A combination of bending the beading to fit as much as possible, and filling the remaining gaps with wood coloured epoxy should make for an acceptable joint.
A shallow bead of 5 mm. thickness allows room at the back for the hood, and is flexible enough to bend around some of the corners. At that thickness it can only be about 10 mm. wide, possibly less. It depends on how it looks. It also precludes using clamps to hold the beading in place, but instead it allows brads to be used. The brad holes will be filled with wood coloured glue afterwards, and will be virtually invisible.
Before setting out on the actual beading, I have done some experimentation with some scrap cut to approximate size. The most difficult part is the windscreen area, where the camber of the deck means that the bead has to bend backwards. Eventually I will be able to remove the windscreen and use the screen frame for clamping the beads in place, but temporarily I can push them in with brads.
A trial beading using scrap.
Using an offcut of the piece shown above I can work out where a similarly dimensioned piece on the side will intersect with it, and, therefore, the mitre angle can be demonstrated. This one, cut at 40°, is just about right.
The mitre joint.
After rounding the leading edges and adjusting the width to its best look and most manoeuvrable dimension, four pieces are cut and ready to go when the time comes. I will leave the mitre jointing until the beads are actually being glued down.
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156. The Propeller Shaft Anode
By
way of protecting the exposed metals from corrosion, a sacrificial zinc
anode has been fitted to the prop shaft. This is a 3/4" fit, which
clamps around the shaft and is fixed with bolts and ring washers, as
well as plastic washers and embedded hex nuts. It should be fixed
solidly enough. As the lowest metal on the galvanic table, the zinc
should corrode in preference to any of the other metals on the boat, in
the case of any current leakage.
However, there is no electrical connection to either the rudder or the skeg, so there should be no leakage. There is no electrical or watery connection to any through-hull either. But, just in case something goes wrong this anode should do its job for years to come.
It has been a while since I have worked under the boat, and the spiders have enjoyed their
freedom. The anode is shown bolted to the shaft.
However, there is no electrical connection to either the rudder or the skeg, so there should be no leakage. There is no electrical or watery connection to any through-hull either. But, just in case something goes wrong this anode should do its job for years to come.
It has been a while since I have worked under the boat, and the spiders have enjoyed their
freedom. The anode is shown bolted to the shaft.
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Problems shows higher resolution shots as well.