How tough are skin on frame boats?

Have you seen this video? Yes it is mine, I shot this in the shop yesterday. Got to say it was fun to try to destroy a boat too.

Great video, it certainly lays to rest any concerns I had about durability of SOF boats. What is the type andgauge, or thickness of the fabric? And what is the coating applied?


– Last Updated: Dec-23-10 2:14 PM EST –

Watching it again and I did beat the crap out of that boat didn't I?

That is a a 7 oz. (maybe 8 oz?) nylon. That boat was built a few years ago so I don't remember but that is lightest weight fabric I use. If you were really going to beat one around I would go with the 12 oz nylon.

That boat was coated in ZAR oil based poly. I has been sitting outside most all summer since it's accident. I was surprised at how the coating came off but then again you don't repeatably beat on one either. Good thing is it would be easy to touch up. I think Dura-Tuff would hold up better to that kind of abuse.

With each strike, it hurts. Sacrilege.

I liked the video - thanks for posting. I was impressed by how the fabric, once punctured, was not prone to ripping more like a zipper.

Here are my criticisms (since nobody asked) - at one point it says “try this with your composite boat”, and I’m confident my Souris River boats could withstand that rasp, as well as the rest of it just as well. Secondly, and this is common in these sorts of demonstrations, I am not convinced that the low-mass-high-velocity forces applied are directly comparable to the high-mass-low-velocity forces often encountered in the field. Put another way, walking into a wall is not the same as being hit by a whip.

The point that skin-on-frame isn’t as fragile as one might think was well made, however, so thanks again for posting.

This would turn your FG boat into dust

But fear the oyster :wink:

(Yup I have both FG & Skin boats)

Thanks for posting!
That really surprised me.

Great demo!

– Last Updated: Dec-23-10 1:04 PM EST –

That nylon is tough - but I've paddled with folks who use skin-on-frames, seen them in use, considered building one myself, stripped and retied one that had been canvas-covered and gotten some rot in it - I expected the nylon skin to be that tough or nearly so. The flexibility of both the skin and the frame is part of the strength of that type of construction.

So what kind of accident caused it to be sitting outside all summer? Just curious.

PS: Don't mean to be a wise-ass about it. I'm sure whatever it was would have damaged any boat.

>So what kind of accident caused it to be sitting outside all summer? Just curious.<

Nose job on the asphalt. Tied if off on the trailer in the dark and the front line was caught over something. On the way home it came loose and the kayak was half off the trailer hanging out over the shoulder but I couldn’t see it in the dark. Crossed a bridge and I heard wood snap, not a good sound. When I got to a street light this is what I saw.

Snapped the nose end off and shredded the skin where it drug down the pavement. This was a boat I didn’t like much so it was no big loss. Just glade it wasn’t one of the other on the trailer! Notice how it bent the bars?

Interesting points.
I may be wrong but I still think the force of the hammer is at least as much as hitting something in the kayak at 4-5 mph.

But what really matters in the real world is how sharp is what you hit? Lily dip over a razor blade and your probably sunk!

Like ragwing aircraft…
You mention “fuselage” type construction. You might also mention the covering is typical rag wing aircraft style, like a Piper Cub. Slamming into hail and rain at 100 kts (some MUCH faster), and lasting 30 years, fabric covering has been well proven and makes perfect sense for kayaks. Nylon is amazingly stout stuff but many airplane owners are still using cotton. I’ve always wondered why SOF kayak builders don’t use aircraft dope which draws the fabric drum head tight? In fact, there are other techniques such as stitching and seam tape that haven’t crossed over to boat building. Covering an airplane is basically the same thing.

My next boat will be SOF.

I’ve built two sof with canvas skins. tough…I’ve paddled my baidarka through ice, never any damage. But, I have yet to run into a hammer while paddling…

Nice demo.

Tradition probably
I am not well versed in airplane covering methods but I have looked a little about it. I have seen a boat that had the skin glued on and the seams taped and honestly I didn’t care for the look. Maybe it was not done well but the taped seams looked… well taped. They were very obvious. So I have never tried it.

I don’t think Dope is used on the polyester fabric is it? Wasn’t that just for cotton/canvas and help to shrink it. The polyester will heat shrink and accept paint as a finish.

For almost all of my boats I now use polyester because it is so easy to finish and I love the heat shrink ability. I find it has some advantages for me over nylon. What I use is not aircraft weight, it is about twice as heavy. Aircraft weight is very light and would damage way to easy on a kayak.

I love it! I haven’t found any hammer on the water yet either.

One of these days I am going to try canvas. I live inland and paddle fresh water. Always read that 3 years ia about as long as canvas would last in fresh water so I haven’t tried it yet.

After seeing the demo, I would not say
that SOF is fragile at all. But I also think that hammer blows are not like the lower velocity, longer persistence displacements that my composite boats have survived.

To the extent that SOF construction can give people the kind of kayaks and canoes they want and need, it deserves more of the market.

I think the best composite construction
(S-glass outside, Kevlar inside, epoxy resin) could withstand that vehicle roll just as well.

Dope isn’t durable enough

– Last Updated: Dec-25-10 9:24 PM EST –

I've seen SOFs with doped canvas skins and it doesn't hold up well to the kind of abrasion a kayak sees. Aircraft aren't subject to the large, skin-stretching impact that are common when kayaking. I also suspect that part of the problem is that, unlike in an aircraft, the skin on a kayak gets soaking wet on the inside, which probably helps to undermine the adhesion of dope the the fabric.

While dope does shrink cotton, it doesn't have the same effect on other fabrics. Aircraft polyester (Ceconite) is shrunk with heat and it's specifically manufactured for that. Although I haven't tried it, I wouldn't be surprised if dope doesn't bond well to Nylon.

I thought this was the gold standard
for SOF abuse:

Or maybe this (the 1:50 mark):

What’s the point?
Nylon or polyester is more durable and won’t rot like canvas will. “If it ain’t broke, don’t fix it.”

Reply: Skin on frame kayak
On the water, there is nothing like the lively feel of a skin boat silently gliding through the chop and how one can feel the waves through the skin as the frame subtly dances and reacts wonderfully to each wave. It feels like you are part of the water. They feel organic and alive.