: As every else is saying, use your eyes. Sight down the keel from one end,
: then the other. Don't be afraid to stop working, sit down and think about
: it and sight down it again. You sense of vision is very refined. If
: something looks uneven it probably is. Keep looking at it until you can
: figure out WHAT is uneven. This is an area where a good workspace can
: help. Uneven lighting can deceive you. The inability to eyeball the boat
: from both ends can trick you.

: It's amazing what accuracy can be achieved with your eyes, a string, and a
: few hand tools. It is not realistic to try for .001" accuracy, but
: .1" accuracy is easy to achieve and you can probably get a lot closer
: to .01" accuracy than you ever thought possible.

: Mike Scarborough
: Friendship Kayak

I will agree with Mike and the others who say trust your eye as you are building the boat. As someone who has done machine shop work (as a hobby in my parent's basement) I used to be able to get a piece of metal in a 4-jaw lathe chuck aligned to within .005" of an inch by eye (since I haven't done it in quite a few years I'd be surprised if I could still do that). At least with some practice, I can confidently say that the eye is easily able to decipher that something is off by as little as .01". I would be surprised if warpage of .05" or less would matter a whole lot in the grand scheme of building a kayak.

Paul