When joining the bottom to the sides on the Peeler it really helps if you support the bottom panel at just the very bow and stern. This induces just the right amount of rocker (sag) into the panel and the sides fit like magic. Also, when you tighten the stitches, push up on the bottom not down on the side.

Sorry I said all those things about you John but I got hung up on the flat bottom part of the Peeler's discription. It just shows that if at first (second, third, fourth) you gon't succeed, go sit down, you're doing it wrong.