: I found out how difficult it is to empty a SOF of water even with
: very large float bags. So I need to make a sea sock.

Wal-Mart has short lengths of nylon on their discount/closeout table for $2. Sometimes it is ripstop nylon. It is not usually coated, but I've seen some which is.

A lot of closely-woven fabrics are water resistant and would work well without being coated.

Campmor, REI, and probably lots of other camping-goods dealers sell a urethane-based tent-fabric sealer by the pint, which looks a lot like ordinary urethane varnish. Brush it on your old tent or new sea sock and the fabric becomes waterproof.

I bet you could use the same urethane coating that SOF builders put on their nylon, Dacron or polyester kayak skins. If it wears, put on another coat when needed.

Put it on after you sew your sea sock and it will fill the needle holes as well.

If you make one that fits right you can duplicate it with a Goretex fabric.

Hope this helps

PGJ