I recently finished this stage with reasonable success. The main thing for me was to have multiple reference lines that could be checked and re-checked (darkened them with a Sharpie marker for visibility), and mounting cleats that allowed me to hold the forms in place with spring clamps while I fiddled. I suspect this would not have been needed if I had made consistently square cutouts in the forms, but you can only get so perfect with a jigsaw and file. I used a high-quality, kiln dried Douglas-fir 2x4 strongback that resisted warping nicely, drew straight reference lines on it, and never found it necessary to run strings along the sides. Basically checked the marks over and over and over, especially while fastening to the cleats, until in the end, I had them all in within 1/16", I think.

Incidentally, an easy error to make is to have all the front forms aligned together, and all the rear forms aligned together, but to have some kind of kink in the middle because you can't sight from both ends at once. You need reference marks on both sides of the central forms to deal with this, and sometimes I would place my handy T-square on end behind a low form to aid in the sighting. This is also where the straight pencil line on your strongback is a life-saver.

Good luck.

C

: The laundry room project has advanced to the point where the boss has given
: me permission to start work on the kayak.

: I'm about to position the forms on a box beam I built (following the advice
: in Nick's book). Does anyone have any helpfull techniques for both
: aligning them accurately and minimizing my inevitable frustration?

: thanks, EdP