You only need two 1/4 sections. 1/4 of the deck and 1/4 or the hull that you mirror and trace.

take card board and make an L shape - like a fat framing square. have someone hold that flat across the deck and against the side of the kayak. then you take chunks of cardboard (5" wide by whatever length you need) and tape those like tiles to the cardboard framing square touching the deck, describing the shape. Then trace the shape on another piece of cardboard and you have 1/2 the deck. You do that with the boat upside down and you get 1/2 of the hull. You can get a pretty good hull and deck cross section that way. The more little filler pieces you tape in, the more accuracy you get.