Hypalon is extremely dangerous - toxicity and flamable fumes etc. there's other ways to seal dacron. Why dacron? I investagated fabrics to the max. I use Polyester - 13 oz boutht from Dyson. Recommended by bill Lowe as well as Dyson. It has a 15% heat shrink (extreme heat - heat gun)unlike nylon which will loosten up in cold conditions and shrink on a hot day (very unstable). I would highly recommend that. I sealed my skin with epoxy,. I have a friend on this board (Pete Strand) who uses spar varnish with good results - same skin. The lacing will be waterproof with whatever coating you put on since it's double stitched. (stitched together and rolled over and stitched again.

By the way, two years on the epoxy finish over Poly. and it held up perfect. No problems.

I would highly recomment buying "Building skin on Frame Boats" by Robert Morris. Also "Building the Skin Bairdarka" by Wolf Gang Brink. You can get them through Sea Kayaker magazine and other places. Great book. You have to read as much as you can etc. There's no one way to build a skin boat.

As far as Hypalon, I'd forget it. Bill Lowe in Mass. overed to do mine and a friends for the cost of the materials. (nice guy) He knows you can't easily get it - and he wears a full breathing suit when he works with it.