You may want to try a different building method. I built, many years ago, a small 11.5 ft solo canoe using Tom Hill's building method. Its made of 4 mil marine plywood and uses no glass. You join each board to the previous one by epoxying along the edge. This creates a very lightweight boat and mines lasted 8 years, though it doesn't see rough weather or use. Its a great little boat to go relax and explore in. Tom Hill has a book called Ultralight boat building. I believe the offsets for the solo are in the boat. At the time, I bought the full plans from Tom. He use to build and advertise more, but I haven't seen him in some time, but his book is still available.

Good luck

: 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?