I participated in a skin on frame course years ago in central BC, Canada. The boats were a peapod style that a small group could easily finish in 4 or 5 easy days. We lashed the fabric on with nylon cord reasonably tightly. No waterproofing was required - we just tossed the little boats into the lake and paddled around - took in no water at all. Unfortunately the instructor was not as generous with his information as Jeff Horton and would only say we could buy the stuff from him... It was a plainly woven white fabric that looked a lot like your Polyester - felt like woven fibreglass. I wonder if you (Jeff) know of such stuff and if it is available, or too pricey to be used? Thank you.