Check out the Greenland Technique Forum for lots of discussion on what and where to get the "S" in SOF.

I bought the 12 oz ballistic nylon from Dyson, Baidarka, Inc. in Bellingham, WA. They do not have a web site, but search the Greenland forum for a current email address. Lots of people have used polyester from Tacoma Tent and Awning. You can also get most anything you need from Robert Morris's Brewerery Creek Boat Shop. These materials are sewn and then usually painted with varnish.

Other's like Tom Yost prefer to use vinyl coated polyester which he glues together rather than stiching. These skins do not need painting.

Search the archives of both this forum and the Greenland forum for more info.