This new offshore fishing boat being built by Kevin Agee in Hampton Roads, Virginia, is progressing nicely. It is entirely his build project and I get to do the drawings for it and to help out occasionally at weekends, sometimes offering guidance, other times supplying an additional pair of capable hands. I always return home after a day working on the boat feeling tired but happy with the progress.
Last weekend we did the last preparation work on the framing to receive the bottom skin, dry-fitting the plywood panels from stern to bow, fine-tuning bevel angles on frames, girders, keel and stem in the process. The bottom skin is two layers of 9mm plywood and this post is about fitting the first layer.
Kevin had already done most of the bevel work and dry-fitted two full sheet-lengths both sides, where the sheets fall nicely into place under gravity alone. The further toward the bow that we get, the greater the twist that the plywood must adopt. It doesn't do this readily and must be coaxed by various methods. There is only 3 degrees of change to the bottom angle (dihedral) in the aft half of the hull but there is 51 degrees of change in the forward half. This is to form an efficient planing surface aft, combined with bow sections that will give a soft ride into short seas, so the bottom has to twist to give the characteristics that we want.
The photo below shows some of the preparations that have been made to the structure ahead of fitting the bottom. The large member across the top of the photo is the keel, which has been planed at an angle to match the edge of the frame. There is a shallow saw-cut visible on the top of the keel, which is used, one on each side of the hull, to gauge the correct bevel angle. The intersection of the two cuts also shows exactly where the centreline of the keel is, needed when fitting the bottom panels. The white is a structural epoxy fillet to bond the frame to the keel, easier to do now than in the bottom of the bilge when the boat is right-way-up. The green semi-circle is a fibreglass pipe that has been cut in half and bonded into the edge of the frame. This is to form a scupper for bilge water that may get into the bottom of the hull. Each frame will have one of these scuppers fitted each side of the keel, to lead any water to the transom for draining or pumping.
In the process of dry-fitting the panels they must be trimmed to their final shape. Kevin cut the sheets to shapes that I provided in the form of full-size patterns but they must be fine-tuned along the centreline and chine for a perfect fit. Once that perfect fit has been achieved and the panel is securely clamped, it should have some locating screws fitted, which will assist greatly with getting it back into that exact position when gluing it into place, with slippery glue trying its best to put the panel anywhere other than where you want it to be.
In this next photo the forward sheets of the first side have been glued in place. The temporary screws with fender washers are holding the plywood securely against keel, stem and girders but the clamps have been left along the chine. The strips of plywood on waxed paper across the joints in the middle of the panels are there to align the joints in case some glue has found its way into the joints; we don't want it to glue the edges misaligned.
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