it would be great if you could send a picture.  how 'out of plumb' is it?

in terms of boat performance, it would take a very large distortion to really have an impact.   also, you can be out of plumb, but basically have a straight keel line....so sometimes the problem really is isolated to the ends of the boat....and can be fixed with a relatively short/single cut down the keel line where the two side pieces meet and then just slightly shifting the bow/stern back into plumb without really touching the bottom panel.

   I wish I could post a picture but for some reason I seem to be having trouble getting the URL from Flickr to copy and paste a link to the image.  In any event, I have now concluded that perhaps my problem is a twist - the bottom at the  bow and stern are off in opposite directions -I'm not sure how to measure how far off line it is but the "out of true" doesnt seem to be quite symmetrical - a bit more off on the port than the starboard side.  As best as I can tell, at th epoint where the bottom meets the side, along the bow line, the angle changes about 3 degrees though to the eye it looks a bit greater.

   Up front. I don't know anything solid about how to fix this problem. But if you still have to put fiberglass cloth on the bottom of your boat, perhaps you can attach something temporary to bow and stern, overcorrect the twist by a little, apply the fiberglass cloth, and see if that fixes it. . . . Try to get better advice from someone who has actually dealt with this problem!

   On further thought, I'd use weights and levers to try to correct the twist BEFORE applying any more fiberglass. Once everything is as true as you can get it and stays that way without leverage, apply fiberglass to the bottom to lock everything in place.

  You may need to heat the length of the hull on both sides to soften the epoxy so it will slip into the correct position. But it is had to say how much weight or preasure will be needed to get everything to align.

  You may need to heat the length of the hull on both sides to soften the epoxy so it will slip into the correct position. But it is had to say how much weight or preasure will be needed to get everything to align.

fwiw....i think there could be a combination of ideas that could work here.

if you could basically brace the hull into the correct position as a start and then use a heat gun to heat up the fillets so that they give a little.  i would bet that when they reharden...the boat will have its twist corrected.

you would want the hull facing up (as if in the water) so you could apply heat directly to the fillet....that would be best as you could dial up the heat a bit more than you could if you were heating up the epoxy by applying the heat to the wood and potentially burning the wood.

having a heat gun (as you may have read in other posts) is a great tool to help correct some of the common mistakes that happen when building a kayak like this.  heated, the epoxy becomes soft (like bubble gum) and can easily be cut or slightly reshaped.

h

   Thanks for the suggestions. Since impatience got the best of me last weekend I have already glassed and applied 3 coats of epoxy. I do have a heat gun but is it now too late to try to remedy this?  I assume at this point the glass and epoxy are holding the shape of the boat as much - or more - than the fillets.  Bruce

   Could you put it in the water on a very calm day and then give it a good push to see if it tracks straight? You might add some weight and repeat the test in case that matters. Maybe it doesn't need fixing.