Argh, Just hit some key or other, and all my message I typed vanished. Here is an abreviated version:

Basically, I think the fiber tape method, should alow you to get a perfect fit.

the method is as described in Nick Schades Book, 'The Strip Build SeaKayak' (or somthing like that, I do not have it on hand) I suggest you try and borrow a copy from the library, or buy one.

reaching inside you can push the hull and deck into alignment, and run tape from hull to deck to hold it there. if you do this every few inches it should pull everything together really well. You will have to ensure the kayak can then be joined from the inside, thickened epoxy on the edge of the hull and deck may suffice, but ideally you would run the fiberglass on the inside.

I was able to fix a gap of about 1.5cm, down to about .5mm.

good luck

Myrl