I wanted to get some cross-sections from one of my boats, and thought of a (fairly) quick and accurate way using bending plywood. This technique has been described for making forms and cauls in guitar-making.

(A good plywood dealer shold be able to get you bending plywood; it's useful and not too expensive. The stuff I had in my scrap pile was about 4.5 mm aka 3/16". NB- You can buy 4x8' sheets that bend either across the width or length- specify which you want if you have a large project.)

Bending ply bends easily but makes a stiff lamination with only two layers.

I cut a pile of strips about 1/2" wide, and laminated right on the hull, using woodworking glue.

(It's a good idea to use lots of decent-quality masking tape on the hull, for protection....especially if the boat belongs to SWMBO. ;-) )