Here's the second part of the building sponsons with divinycell/Airex and CA glue pics I published a few years ago at the old International Waters gallery.
Missed part 1?
Do note that these build pics are ment to show the principle of building it with CA glue and give you ideas to do it yourself. The actual design of these sponsons are the ones I did in 2006 that are the ones that are included for the first Freebie PDF drawing I published a year ago. Today I would not make them this way personally (see the Freebie .21 V1.09). At that time we thought it was needed with non-trip chamfered cuts etc. But we have now found out they arent needed so the over all width of the sponons can be made narrower = the same as the width of the running surface. The narrower design of the sponsons makes it kind of not needed with the anti-chine cut also but thats up to you.
If, not - think about it for a while and it will sink in... ;)
(Updated: use normal 1.5 mm airplane birch plywood instead - it will be lighter and stiffer!)
use normal 1.5 mm airplane birch plywood for the top instead. It's lighter and makes the sponsons more rigid.