: What is the canvas or nylon typically coated with? I have seen lots of
: coatings: polyurethane, exterior paint, hypalon, ect...

Hi Ben,
Canvas is mostly coated with oil-based paint, most varnishes make canvas brittle and weaker. I use exterior enamel paint, some use latex roofing paint.

Nylon can take most varnishes, some better than others. Coelan varnish seems to get good reports, I can't comment on other brands as the names are different between US and EU. Confusing.

Hypalon and neoprene paint can be used on canvas successfully, most life-rafts and many inflatables were made of this combination in the past. I think it works out a bit heavier than paint but very long lasting and flexible. Their problems are to do with high VOC's on application and hypalon takes a good while to cure fully.

Do a search on skin coatings here, and also check out the qajaqusa site. On a search, you're likely to get some good ideas.
Another place to search is the Baidarka Mailing List. There's a lot of information there going back to '95.
http://robroy.dyndns.info/baidarka/

Hope this helps,
Mike Savage
South West Cork