Yes, it literally caused some additional concavity in the keel. Now that I go back and look at the pics, it wasn't as bad as I recall. I still paddled the kayak for about a year, and it was fine. This was the 1931 Disko Bay. I had drawn fuselage forms off Harvey's survey. There was a LOT of pressure in bending the gunwales into the forms, probably due to the stiff southern yellow pine plank I used. I recall wrestling the stringers in to place, then when all lashed up and I released the first and last forms from the table, it literally sprang unto the shape it wanted to be in, darn near jumped off the table. But, the 1931 has a bit of concavity anyway.

If you want to see what I did, I have put up my drawings and some pics of the finished build.

http://tduncandesign.com/1931/CMC-IV-A-375-1931DiskoBay-fuselageforms-v1-thomasduncan.pdf

http://tduncandesign.com/1931/1931-tduncan-fuselagebuild.zip

I actually took my PDF drawings down to the local sign shop and had the guy cut them out on the shop bot from some outdoor signboard. Ultimately, it was neat, but I probably could have just bought a decent Bosch or something.