: There has been some mention of nylon puckering or getting loose when wet.
: Have you found this to be the case? I am planning to build a skin-on-frame
: boat, and am trying to decide between polyester and nylon for the skin.

I just finished skinning a boat with 13 ounce polyester from Dyson. I selected this fabric after seeing how incredibly rugged Bill Low's boats are when skinned with this material and coated with Gaco UA-7000 (over two sealer coats of ZAR satin urethane).

The boat came out well, but there are pro's and con's to the material. First off, it doesn't stretch much and it doesn't shrink much. It won't go limp when it gets wet, but it has to be pulled VERY tight when sewing, since you cannot shrink it appreciably afterward. Heat shrinking will help remove wrinkles, but that's about all. The fabric wrinkles badly when folded and they don't come out easily, so pay the extra money to have it shipped rolled .

I used Bill Low's skinning instructions and sewing method, which are optimized for this fabic. They work well, but sewing is very slow. Not counting areas that I screwed up and had to re-sew, I would estimate it took twelve hours to sew the deck seams. The result is attactive, but I wasn't sure it was worth it at the time. Now that my hands have stopped aching, I look upon it a bit more fondly.

The other consideration is the cost. This fabric is $6.00 per running foot, 3-4 times the cost of canvas! The skin material for my boat cost $120, which is more than I have into the entire frame. The material is 80" wide, so you end up paying for a lot of fabric that you don't use. I have a 22" x 20' section left over. I guess I could make cockpit covers and paddle cases out of it, but there are a lot of cheaper fabrics available for such purposes.

While I'm really impressed with the ruggedness of the polyester, I'll seriously consider using nylon on the next boat. Nylon is stretchier and can be shrunk after skinning. If it's pulled tight during sewing, shrunk, then coated properly, it should not go slack when it gets wet. (You may even want to consider wetting it with a spray bottle as you sew.) It's also considerably cheaper than polyester. I have a sample of the 26 ounce nylon that Dyson uses on their boats, and it's ridiculously heavy and thick. I believe they also sell a 14 ounce nylon that makes nice boat skins. Nylon is not as UV resistant as polyester, so it may degrade in time if not coated with something opaque like Hypalon.

As for coatings, my boat has three coats of ZAR on it, applied with a roller. It's well sealed, except for a few of the stitching holes on the deck. I'm going to put another coat on the stitching, then coat the whole boat again. I have a half gallon of Gaco UA-7000, but I haven't decided whether to use it on this boat yet. It's very expensive ($100) and I'm not sure if I like the boat enough to invest that much extra money in it. I may save it for the next boat.

A friend skinned his boat with canvas and coated it with airplane dope. It looks nice, but it doesn't seem to be holding up too well. The upside is that the finishing took only one day.

I guess the bottom line is that canvas is cheap, quick to sew, quick to finish if you use dope, but not very rugged. Nylon and polyester are more expensive, more durable and take longer to finish. As the saying goes, "you pays your money and you takes your choice".