: This past spring I built a sized down version (9 1/2') of a Wee Lassie. Using
: 6 oz cloth, it ended up weighing about 18 lbs. Now I want to try to build
: a Sairy Gamp, and would like to keep the weight as low as possible. I was
: wondering if it is absolutely necessary to fiberglass both inside and out.
: I think I can lower the weight by about 3 lbs by using 4 oz cloth, but I
: would like to get it lower yet. Would it be a very bad idea to fiberglass
: the outside only, while coating the inside with 1 coat of Epoxy to seal
: it?

Not a good idea. The strength comes from the plies on both sides. Study this page and it might help you understand what is going on with the stresses. http://www.oneoceankayaks.com/Sandcore.htm