I cut out the forms from 3/4 ” plywood for strength.  If you zoom in on the image, you will see the marks for the cutouts for the 3/4 ” x 1 1/4 ”  oak longitudinals.  The oak will bend around the forms and give a structure for the 1/4 ” marine plywood planking.  Once the plywood is screwed to the longitudinals, and the the hull is completed the forms are removed leaving a strong but light boat hull.

N1JXQ