So I got the plywood, some good quality, from what I can tell, marine fir. That in hand, it was time to start getting big pieces together, starting with the sides.
The plans call for five 4×8 sheets of 1/4″ plywood, 2 1/3 of which go into the sides. The Getting Started in Boats write-up assumes one has a nice, big, level area on which to do the layout. I was using our lawn, that leaves a bit to be desired in the “level” dept. To keep things in line, I used clamps to keep the sheets aligned while I plotted the side panels. I was blessed with a) having spline weights from my design dabbling and b) having a nice off-cut of 12′ 1x that was a perfect batten. I had to pend a bunch of time and hands-and-knees with a straightedge and pencil, but I was able to get the sides out fairly easily.
The design is tailored to creating full sub-assemblies like this and fitting them together into the whole. Thus one builds the sides out, with sheer clamps and chine logs attached, the full seats, and the bottom panel, with keel attached, and then brings the sides together around the seats. There are no forms; the seats provide the athwartships dimension when they are installed “in real time.” I decided to get the sides done first and just rough-cut the bottom panels because, since I am moving the chine log in-board, these panels will have different dimensions than the plans. I’ll allow myself enough and then fit them to the actual bottom area when the sides come together.
The pieces of the side panels are to be joined via butt blocks. These butt blocks are defined nowhere in the write-up, except that they are 6″ wide. I took their length from the relevant station on the plans (they all overlap a station perfectly), leaving some wiggle room. I used some pieces of spruce 1x I had around, planning them down to 1/2″ (the plans call for 3/4″ bronze ring nails, so 1/2″ blocks plus 1/4″ plywood would fit perfectly). The write-up call for gluing the block to each piece of the panel and then nailing the block to the sides. The clear assumption is that the block is less than 1/2″ because it talks about hammering the ends back over. That just seems so sloppy to me.
I glued up the block and one of the pieces and then used spring clamps to hold the block in place. I then carefully flipped the work and nailed through the side piece into the block, using a metal file to take down the slightly protruding nails. I then flipped the work back, added glue to the adjacent side piece, clamped it, flipped it, and nailed that. This worked well. I just bought the spring clamps, and I have no idea how I have survived without them. They have been invaluable on this project and I suspect I will put many miles on them. I got 6 fairly basic ones and that is perfect in number and quality.
One problem I did have with my method is that the butt blocks proved fairly fragile. You need to be very careful moving the panel around, once brought together as the weight of the pieces creates significant pressure at the joints. I learned that the hard way, and had to add an extra block when one of mine split. I attribute this not only to the stresses of the large panel, but also to my choice of lumber. I think in the future I would glue spare pieces of the 1/4″ plywood together into a 1/2″ laminate and use them. The grain of the 1x was running exactly where it was most likely to fail under bending stress and I missed that. I also put the nails too close together, helping open up the splits. There is no specific guidance on this, but I moved to 4″ centers, staggered a bit, with better results.
What I would most strongly recommend regarding this last point, however, is to not move the panel much until you get the sheer clamp and chine log on as these stiffen the panel up much better. I would prepare both in advance and add at least the sheer clamp immediately after completing the butt block step. There is no reason you can’t and it will make things much safer.