The side coaming timbers arrived already planed to thickness, as my planer will not cope with 300 mm. width. One of them was a beautiful piece of clear, straight grained wood, but the other has some slight knots. These do not weaken the timber at all, as they are so small, and, in fact, they give it an interesting reflection in the right light. It is just a pity that they will not be the same on both sides.
The
first job here is to cut the wood to approximate size and fit it into
the slots provided for it between the windscreen side frame and the
carling, and between the rear seat trim and the carling. An idea of its
length can be ascertained by holding it in position against the screen,
and, using a batten as a representation of the top of the coaming, an
idea of the diagonal angle of cut can be devised also.
Approximating the length by holding it in position.
A batten represents the top, and a diagonal cut is made along that angle.
Approximating the length by holding it in position.
A batten represents the top, and a diagonal cut is made along that angle.
The
trimmed piece now has to be slid alongside the screen lateral frame, so
the portion of subdeck which runs in front of the screen has to be
removed. The rear, athwartships coaming is also unscrewed and removed
to allow the side piece to slip back hard against bulkhead E. The side
piece is then gradually introduced into both purpose-made gaps, but
they lie at an angle to one another, so the timber has to twist
to accommodate them. When both ends are engaged there is a gap in the
middle between coaming and carling, because of the curvature of the
hull. For this reason, the side piece has had to be cut a bit long, so
that it will not be pulled up short when the gap is closed.
Up alongside the rear seat (left), and demonstrating the gap at midships level (right).
The coaming is slipped down into position.
Up alongside the rear seat (left), and demonstrating the gap at midships level (right).
When
it is fully engaged, the piece is knocked back hard against the
bulkhead, and scribed for the correct angle across its width. It is
then removed, cut along the scribe line, and replaced again. A mark is
made on the piece at the level of the top of the windscreen frame to
mark its correct vertical height.
The coaming is slipped down into position.
One of the defining looks of a slipper launch is the straight coaming top running above the curved deck.
The
athwartships piece is now
replaced, and the dovetail is scribed against the side piece to mark
the pins, with the aid of the vertical mark at windscreen level to
align it. With the pins
cut, the side piece is put back, engaged into the back piece to check
for fit, and the subdeck level is now scribed onto the outside of the
coaming. With the deck level marked, a parallel line can be plotted for
the bottom of the coaming, and the excess cut off it. It still sits a
bit proud on the top, but that will be trimmed later.
The deck line and lower cut line are marked on the outside of the coaming, and a batten is used to fair the latter.
The dovetail is a snug fit, especially on the inner corner, where it will be seen by the passengers.
A line now needs to be plotted which overlies the middle of the carling, between the bottom of the coaming and the deck line. This is the line through which the coaming will be screwed to the carling, and where a trench will be placed to house a contrasting cockbead. The bead serves the twin function of hiding the screw heads, and reflecting the colour of the steering wheel and the bead on the kickboards.
The line for the cockbead trench is just seen 40 mm. above the bottom edge
of the coaming.
The trench is cut by a router attached to a fence which follows the line of the bottom of the coaming. Because the coaming is gently and evenly curved, a standard router fence of short length can be used. If it does not follow the carling exactly in the centre it does not really matter. The screws are backed up by epoxy anyway. The first screws are placed sternmost, and the coaming is bowed to take up the gap between it and the carling as each successive screw is driven in, working forwards. When all screws are in, and the coaming lies snugly against the deck, the front side of the lateral windscreen frame is scribed onto it for trimming. The counterbored screws attach the coaming to the lateral frame, and the bores are eventually filled with plugs.
Once again, all screws are removed, and the coaming too, so that its opposite number can be fashioned. Once it is, the athwartships piece is glued and screwed to bulkhead E, and the side coamings are similarly affixed, gluing the dovetails, carlings and windscreen frames. The plugs are glued in and the cockbeading is added. Final shaping of the top edge of the coamings can take place once all this bog work has set.
A forward extension of the coaming has to be added to cover the top of the forward lagging strips in front of the windscreen, under the deck, but this piece is not seen, so does not need to be of continuous grain pattern. In other words, it can be fashioned from an offcut.
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116.
Trimming the
Windscreen The deck line and lower cut line are marked on the outside of the coaming, and a batten is used to fair the latter.
The dovetail is a snug fit, especially on the inner corner, where it will be seen by the passengers.
A line now needs to be plotted which overlies the middle of the carling, between the bottom of the coaming and the deck line. This is the line through which the coaming will be screwed to the carling, and where a trench will be placed to house a contrasting cockbead. The bead serves the twin function of hiding the screw heads, and reflecting the colour of the steering wheel and the bead on the kickboards.
The line for the cockbead trench is just seen 40 mm. above the bottom edge
of the coaming.
The trench is cut by a router attached to a fence which follows the line of the bottom of the coaming. Because the coaming is gently and evenly curved, a standard router fence of short length can be used. If it does not follow the carling exactly in the centre it does not really matter. The screws are backed up by epoxy anyway. The first screws are placed sternmost, and the coaming is bowed to take up the gap between it and the carling as each successive screw is driven in, working forwards. When all screws are in, and the coaming lies snugly against the deck, the front side of the lateral windscreen frame is scribed onto it for trimming. The counterbored screws attach the coaming to the lateral frame, and the bores are eventually filled with plugs.
Once again, all screws are removed, and the coaming too, so that its opposite number can be fashioned. Once it is, the athwartships piece is glued and screwed to bulkhead E, and the side coamings are similarly affixed, gluing the dovetails, carlings and windscreen frames. The plugs are glued in and the cockbeading is added. Final shaping of the top edge of the coamings can take place once all this bog work has set.
A forward extension of the coaming has to be added to cover the top of the forward lagging strips in front of the windscreen, under the deck, but this piece is not seen, so does not need to be of continuous grain pattern. In other words, it can be fashioned from an offcut.
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No,
it does not have to be cut down. I mean to add some trim to the bottom
of the frame. To give the windscreen a more finished look, it needs to
have some beading added along the bottom frame pieces, to meet the
coaming flush with its bottom. The exact thickness of the bead can be
adjusted to accommodate the level of the coaming, but should preferably
be between 5 and 10 mm. from an aesthetic point of view. Strips of
spare mahogany can be used here, simply butted against one another and
the coaming, and screwed and glued to the frame.
My coaming hangs just 8 mm. below the bottom of the untrimmed screen, so some strips of 8 mm. thick mahogany are rounded on one edge and fitted with appropriate angles to meet one another and the coaming.
My coaming hangs just 8 mm. below the bottom of the untrimmed screen, so some strips of 8 mm. thick mahogany are rounded on one edge and fitted with appropriate angles to meet one another and the coaming.
The 8 mm. underhang.
If
the 8 mm. seems to be too big there is enough leeway to knock the
coaming up a little. The carling is 56 mm. wide, so a few millimetres
will not make any difference to the screw hold. But it is necessary to
decide on this step before the front of the coaming is trimmed down to
windscreen level, and before the screws are driven into the carling
through the trench. A scrap of wood is shaped and positioned so as to
get an idea of the final look, and 6 mm. is settled on as the best
blend. The coaming is knocked into position, and checked to make sure
that the alteration has not affected the fit on the dovetails. Then the
front of the lateral windscreen frame is scribed onto the inside of the
coaming, its second last adjustment. (One more comes when the coaming
is fixed onto the carling, and the gap is taken up).
6 mm. scrap is used to represent the beading.
Before removing the coaming for the routing of the trench and trimming of the top side, the beading is made and fitted so that it butts against the coaming tightly, and meets its opposite member and its centre piece at the correct angles. It is screwed to the underneath of the windscreen frame, and will later be glued as well. It is quite a complex job to get this trim right. The central vertical member of the windscreen frame was initially cut as a parallelogram, so that its bottom end is cut horizontal, parallel to the waterline, whereas the transverse members of the frame are merely sloping, such that their bottom edges are at right angles to their sides. Thus, there is a discontinuity of angles between them all, and the trim has to be cut on compound angles to match up. There is no way of taking accurate measurements on these small parts with a sliding bevel, so I have to resort to trial and error cuts on scrap. Furthermore, the presence of the coaming now makes getting into and out of the boat more awkward, so I am glad that the cockpit area is almost complete.
The beading is rounded and cut to fit.
It is a bit of a bother removing the coamings. The twist in the timber which is necessary to follow the slope of the hull makes it a very tight fit. Rather than remove it now, trench it and replace it for screwing, the gap is closed with clamps and the coaming front end is scribed for the final time. The cut here can be a tiny bit shy of the line so that any last adjustment can be catered for, and the small amount of overhang can be shaved back to windscreen frame level after the coaming is glued in..
Now, all three coamings are removed, the side ones trenched and trimmed, and their bottom edges rounded on the inboard side. The top sides are rounded on both sides.
Coaming trimmed, trenched and ready for screw attachment.
6 mm. scrap is used to represent the beading.
Before removing the coaming for the routing of the trench and trimming of the top side, the beading is made and fitted so that it butts against the coaming tightly, and meets its opposite member and its centre piece at the correct angles. It is screwed to the underneath of the windscreen frame, and will later be glued as well. It is quite a complex job to get this trim right. The central vertical member of the windscreen frame was initially cut as a parallelogram, so that its bottom end is cut horizontal, parallel to the waterline, whereas the transverse members of the frame are merely sloping, such that their bottom edges are at right angles to their sides. Thus, there is a discontinuity of angles between them all, and the trim has to be cut on compound angles to match up. There is no way of taking accurate measurements on these small parts with a sliding bevel, so I have to resort to trial and error cuts on scrap. Furthermore, the presence of the coaming now makes getting into and out of the boat more awkward, so I am glad that the cockpit area is almost complete.
The beading is rounded and cut to fit.
It is a bit of a bother removing the coamings. The twist in the timber which is necessary to follow the slope of the hull makes it a very tight fit. Rather than remove it now, trench it and replace it for screwing, the gap is closed with clamps and the coaming front end is scribed for the final time. The cut here can be a tiny bit shy of the line so that any last adjustment can be catered for, and the small amount of overhang can be shaved back to windscreen frame level after the coaming is glued in..
Now, all three coamings are removed, the side ones trenched and trimmed, and their bottom edges rounded on the inboard side. The top sides are rounded on both sides.
Coaming trimmed, trenched and ready for screw attachment.
The
rounding of the bottom of the coaming and the inboard top side is
stopped just short of the windscreen beading and lateral frame. Later
it will be blended in by hand sanding. At the stern end it stops just
short of the seat back, and, topsides, continues to the dovetail joint
on the inside and right through on the outside.
Next,
all the screw holes are drilled into the carlings and the screen
lateral frame. There will be no time to waste once the parts are coated
with epoxy, so it helps to have everything ready as much as possible.
The front end of the coamings have to be angled to match the screen,
but I can do that in situ with a Japanese saw. It will mark the screen
frame a little, but that can easily be sanded out.
Here, the coamings are screwed onto the carlings, ready for gluing.
The front of the coamings is trimmed back to the screen frame. The finial still needs some work to blend in to the
coaming better.
By the time I finished this work seen above it was December 20th., and the family was about to arrive, complete with screaming kid, for the Christmas break. As I am the cook in the house, as well as the boat builder, I probably won't get much more done before the New Year. The January schedule is already planned and can be seen on the next page.
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Here, the coamings are screwed onto the carlings, ready for gluing.
The front of the coamings is trimmed back to the screen frame. The finial still needs some work to blend in to the
coaming better.
By the time I finished this work seen above it was December 20th., and the family was about to arrive, complete with screaming kid, for the Christmas break. As I am the cook in the house, as well as the boat builder, I probably won't get much more done before the New Year. The January schedule is already planned and can be seen on the next page.
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