Thread for SOF

Submitted byfrankp onSun, 09/30/2018 - 23:15
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Kayak Building

I built a SOF kayak a while back that I skinned with a PVC skin.  Turns out that the way the skin fit the frame didn't allow me to get a good seal on all the seams and it took on a lot of water.  I was bilging every 15 minutes.  So, I've decided to reskin it with a nylon/polyester (not sure which) skin.  The skin is already treated and is incredibly light, I would say 6 or 7 ounces at most.  

My question for you fine folks is what type of thread/line do you usually use for tying and tightening nylon skins and what is your preferred treatment after the skin is on?  Is one sealant better than another for particular fabrics?

JayBabina

Mon, 10/01/2018 - 08:31

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I used artificial sinew.

Some people peel it off thinner since its a flat strand that's waxed composed of many thinner strands. Some use braided fishing line.

As far as leaks, most builders use a fabric sheet  that wraps around the boat and gets sewed on the deck and above the water line on the ends. Most people use poly/varnish for the finish.

 

Thanks, Jay.  I was planning to use a varnish of some kind but wasn't sure if people had found better options that I haven't read about lately...

JohnAbercrombie

Mon, 10/01/2018 - 18:39

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Frank:

A few of my friends have built SOF boats and they have all used untreated fabric that they shrank with heat and then treated with some sort of 'goop'.

https://www.skinboats.org/store

A known workable system might be easier, but it sounds like you already have purchased fabric for the new skin. (?)

JohnAbercrombie

Mon, 10/01/2018 - 18:41

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I forgot to add that those boats are quite rugged and seem to have held up over a lot of use.

John VanBuren

Wed, 10/03/2018 - 06:57

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I use dental floss to sew mine. I prefer the unwaxed kind but have found the waxed also works.

John Van Buren

Brian Nystrom

Thu, 10/04/2018 - 17:54

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For the three that I've built, I used 40# test polyester "squidding" line. One inexpensive spool is enough for several boats and it's very strong. After trying both Nylon and polyester fabrics, I will only use the latter now. Nylon skins tend to go slack when they get wet (Nylon absorbs moisture), but polyester skins are unaffected. Most polyester material with heat shrink to some degree. I use a steamer, which eliminates the possibility of scorching or melting the  fabric.

Nylon is also finicky when it comes to what finishes you can use. You have to use an oil-based or two-part product. I've used oil-based polyurethane varnish on all three boats, plus a couple of re-skins, and I've been satisfied with its performance.

The fact that your fabric is already "treated" concerns me. Coated fabrics don't conform well to the shape of the boat and many have a "durable water-repellant" (a.k.a. "DWR") on the outside, which prevents finishes from sticking to it. I strongly suggest that you sacrifice a bit of fabric and do a sewing and coating test, before committing to skinning the entire boat with it. That could save you a lot of grief.

Thanks all.  I ended up using artificial sinew, which I had and worked out great.  The skin was already a waterproof nylon so I did a test in my kitchen with a scrap and was satisfied after 5 hours of no leakage and minimal seepage that it would be fine on the boat.  Unfortunately, tragedy struck on the way to the water this morning.  I'm putting up a new post with pics...

 

frankp

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Skin on Frame