Philo426,
If I scratch build a hull out of wood, I fiberglass the outside, then coat the inside with thined out resin. If I'm working with a commerical glass hull, then it's no problem. The model on the left is a ABS vacuformed hull, and the larger tug is a epoxyglass hull. The larger tug is 80" X 15" X 11", and weighs 165 lbs in the water (40 lb model, 125 lbs battery/ballast). I enjoy working in 1/12th scale.
Mark