Yo Bruce

I am in the final stages of filling and fairing, before sheathing my 2nd guillemot s&g. Great little boats: best ever surfer and rock steady comfortable. I used 2 or three temporary forms to hold the boat in shape while I stitched.

I used 4mm ply for my panels and 4 mm ply off cuts for my temporary stations. Not much pressure goes on the forms, but having thicker material might be handy to staple (never underestimate the power and efficiency of a staple gun in s&g construction - thanks Joaquin )or nails to hold errant panels into shape.

This advantage is likely to be problematical because it is the thin bow sections that gave me problems. This is the most awkward area to put a thicker form. However, the problem would not be insurmountable and easily faired with a few shaves of a plane/rasp/sander ...

Good luck with your project and happy paddling.

Pete