I have this idea for a composite boat design, with a touring kayak main hull, and two retractable outriggers that conform to the sides of the yak when not deployed. I would like to use a surfboard manufacturing method. I saw a video for a bulky ‘kayak’ design, and it was successful, but I am looking to do something a bit lighter and more streamlined. The method is just glass over carved foam. If you use the right foam, you can flush the finished project with a solvent to dissolve the foam, then tape or plug hollow chamber to lighten it up.

Seems like it would be much easier to get a boat to the desired shape from a rough design than with plank or plywood stitch & glue methods.