Pakyak Skin F.A.Q. 1. What specific material do you use for the outer shell? 2. How about Sunbrella fabric? 3. Does the foam need to be full size? I mean cover the bottom half? I'm thinking of going with light weight canvas. 4. Where do you get closed cell foam? 5. Waterproofing the skin: Once only before assembly or on a regular basis during use? 6. Is 1000 Denier Cordura Nylon stuff too thick and stiff for the skin? 7. Could you please tell me more about the closed cell foam you use? I have been looking for the material to use for the outer shell. Do you know what specific material you or anyone else have used? When you're ready to start work on the skin, look for Cordura nylon canvas. It comes in varous weights and finishes (think backpacks, duffle bags, luggage). Unless you're really trying to cut the weight for backpacking, you'll want to use one of the heavier weights for the bottom skin. The skin design pretty well minimizes the number of seams, and most of them are sewn on the back side so any starts and stops and other irregularities are pretty well hidden. How about Sunbrella fabric? Would have to be done to it to make it water proof? I actually did make my most recent skin from a Sunbrella-type polyester fabric. If you remember the skin plan, what I do is to glue a layer of closed cell foam inside the outer skin fabric. So that makes it waterproof on the bottom where it counts. And the fabric itself does shed water pretty well (think umbrella, awning, etc.). But I'm not yet convinced that this will be better than Cordura in the long run. I'm down to making the skin and I'm having trouble finding the foam. Does the foam need to be full size? I mean cover the bottom half? I'm thinking of going with light weight canvas. Any suggetions on that? Well done getting to the skin stage! The foam has three functions in the boat: Glued to the fabric, it makes the skin more waterproof. It cushions the skin against abrasion, particularly along the bottom stringers, and makes it easier to repair any tears or punctures that do occur. It provides emergency flotation if the boat fills with water. So you should think with those points when deciding about the foam. If you use a tough waterproof material for the skin and don't care about the extra flotation, you might get away without using any foam at all. Where do you get the closed cell foam used in the construction of the PakYak? The local fabric stores have sheets of foam, but the minimum thickness is 1/2", and it is clearly not closed cell. For the closed-cell foam, instead of fabric stores look for a foam store, one that sells foam for upholstery, and see if they have it or can get it for you. Or check out sporting goods stores and see what they carry for foam sleeping pads. If all else fails, try this site: www.foambymail.com and get some of their minicell foam. That's the right stuff. It's easy to glue pieces together with contact cement, so you don't have to get one piece full length. They sell what they call Volara foam by the foot, in 60" wide rolls, which is the way I get it. For 1/4" thick it's $4.95 a foot. For one boat I'd buy 6 feet and cut it in half lengthwise and have just one butt joint in the middle. Section 1, Building Step 19: Waterproofing the skin: Once only before assembly or on a regular basis during use? You shouldn't have to do it very often, but it depends on the fabric you use. The most critical thing is to seal the side seams, as the bottom is waterproofed by gluing the foam to the skin and the liner on top of that, and the top deck is mostly out of the water. Nylon fabrics like Cordura usually have a coating on the back that makes them nearly waterproof. If you line the bottom with closed cell foam, then it will be completely waterproof where it counts. You might want to seal the side seams with some kind of liquid rubber or silicone sealer. For the decks, something like Thompson's Water Seal will make them shed water better. I found some sources for 1000 Denier Cordura Nylon. Is that stuff too thick and stiff for the skin? They also sell 500 Denier Cordura Nylon. Which would be preferable? If you want to keep the boat light, I think 500 would be okay all around. But if you want the bottom to resist snags and scrapes better, use 1000 for the bottom and 500 for the top and liner. Could you please tell me more about the closed cell foam you use and where you get it. Sure. This is the type of foam used by backpackers for sleeping pads. It's more accurately called cross-linked closed cell foam. It's a lot tougher than foam that is not cross-linked, such as packing foam. Years ago I bought sleeping pads to use, but I found that there are upholstery shops and even foam specialty stores around that I could get it from. It comes in five foot wide rolls, various thicknesses. I use 1/4" thick foam. I buy six feet, cut it in half and glue the ends together with contact cement to get a 12-foot length.