Well, not to put to fine a point on it, last week was a mess from the boat building point of view, but this week is so much better.
We got the sides and bottom stitched together, made a temporary stem out of plywood and started trying to line things up, they didn't. Then we made frame 18 and 53.5 and tried inserting them. They didn't fit too well at all. The boat was too narrow in the bow area. After a little head scratching and examination of plans, we decided that the instruction "measure from the centreline" in cutting out the bottom either side of the slot was possibly in error, either the frame dimension was right or the bottom dimension was right, but not both.
We pulled everything apart and emailed Tim, but guessed it was the bottom so we glued some wood back on and left it over the weekend, then relofted it and sanded it back. You can also see my freehand cut awful looking slot. We cleaned that up a bit as well.
Monday afternoon we reassembled everything and tried again and it still looked awful, just a boat shaped object. We could not work out how to get the inside edges to line up at the chine. If you got the edge of the side too high near the bow, it would push in - no matter what you did with cable ties. Similarly, if you let the side get out over the edge of the bottom, it would fall down. Most depressing. We gave up. Nothing fitted.
Anyways, driving home from the clownfish cave last night I had this idea - blocks. We screwed little blocks of fibreboard to the bottom to keep the sides from pushing in, and similar blocks to the sides to keep them from falling off the bottom. Combined with cable ties, we found by trial and error that you can get your edges to line up within a Sixteenth of an inch or so in about half an hour. This is what it looks like now.
Just loosen the screw, pack under the block and your problems are over. Of course remember the outside of your boat is looking like a porcupine, but hey, suddenly everything fits. The boat is even square and the bow looks like a bow with 18 and 53.5 cable tied in.