Replacing Canvas With Ballistic Nylon?

[garypete]

I just ran across a 1931 20' Old Town Guide in remarkable condition, needing only new outer gunwales and the canvas replaced. I weighed the old canvas when I tore it off and it was 22 lb. A 20' cedar/canvas is ungodly heavy enough for my 72-year-old body to portage so I don't want to add back another 22 lbs for canvas, filler, and paint.

Instead of canvas, I'm looking at using either dacron that Alex Comb at Stewart River Boats has posted a video on, or ballistic nylon and marine epoxy paint. Has anyone tried using ballistic nylon rather than canvas on a cedar/canvas canoe? The boat's joints are remarkably tight and with sanding should not show with a thin lightweight coating.

I realize an alternative covering rather than canvas will affect the resale value of the canoe, but the nylon can be easily removed and I don't plan to ever sell it. When I can no longer handle this big canoe, I'll offer it as a donation to the Wisconsin Canoe Heritage Museum in Spooner, WI.

 

[Todd Bradshaw]

I think you will find a whole bunch of problems trying to cover a canoe with ballistic nylon. It stretches when wet. It is treated with a fluorocarbon water/stain repellant which will most likely seriously reduce the filler's ability to stick well and I doubt you'll easily find some wide enough to do the job. Paint isn't likely to fill that course weave unless you put a heck of a lot of it on there. The thin Dacron covering on the other hand, has a proven track record. No reason to try to re-invent the wheel.

 

[garypete]

Thanks Todd; I'll probably revisit Alex's excellent video and go with the dacron unless someone comes up with a better solution.

Gentry Custom Boats uses and recommends ballistic nylon for his skin-on-frame boats. How do those boats get around the stretching problem when wet? The designer, Dave Gentry, does not mention any type of special filler for the nylon in prep for paint.

I built a couple skin-on-frame kayaks years ago. I used lightweight canvas for one and brushed on a couple coats of airplane wing dope before painting and it seemed to work well.

 

[Nick Dennis]

John Wilkinson of Valkyrie Craft in Northern Ireland is building canoes covered with ballistic nylon. I am sure if you contact John he can lead you through it. He successfully covers sea kayaks and cedar canoes

See here http://valkyriecraft.com/overview-of-boats/skin-frame-open-canoe

He came to UK Canoefest last year with the Merlin which was very well received.

Nick

 

[Todd Bradshaw]

This shot taken from their video pretty clearly illustrates the problems that I mentioned before with the idea of using ballistic nylon. I guess it's a matter of what level of fit and finish you are willing to accept, but there is no way I'd be satisfied with that level of it on one of my canoes.

 

[garypete]

You've convinced me–overwhelmingly.

Dave Gentry mentioned the problems you cited with nylon and he has discontinued its use in favor of the polyester which George Dyson (of Baidarka fame) uses. I have some samples coming from George.

So now it's a choice between dacron and polyester.

 

[Todd Bradshaw]

Dacron is simply Dupont's trade name for the polyester they make. There are also other trade names for some of the polyester fibers made in Europe. Naturally, there are various weaves, weights, thread counts and finishes produced, but the basic material is the same stuff. I personally recommend it. I got 30+ years of income making sails from it and about 4" of my upper aorta is made from Dacron tubing due to an aneurism repair.

 

[garypete]

If I buy the polyester, should I save a little piece of it in case I have an aorta aneurism?

Congratulations on pulling through that dicey surgery. 97% of people who suffer a ruptured aorta don't. A good friend catastrophically ruptured his and the ER surgeon told us the 3% survival factor for the surgery. Thankfully he waited until after the surgery to divulge that info to us.

What weight polyester would you recommend for a cedar/canvas canoe and do I need a special paint? I'll be using this canoe gently so toughness is not as important as weight. I use a dented up Alumacraft tub when banging down whitewater.

Gary

 

[Andy Hutyera]

For what it's worth:
I have done two canoes with Dacron. It's fun to apply and shrinks amazingly tight with the use of a carefully temperature regulated iron. I used heat sensitive glue along the gunwale (available from Alex Comb) and a special small iron to apply the material. You will need some bias cut tape to apply along the stems. I used aircraft filler to fill the dacron. The canoes came out looking great and weighed about 10 lbs. less than canvas but there the honeymoon ended.
As the hulls naturally expanded and contracted with moisture the dacron would become loose and a bit baggy. This didn't hurt anything but it was not aesthetically pleasing. I could easily remedy the problem by dunking the canoe underwater and letting it sit for a day. The hull would expand a little and the covering was again tight.
The deal breaker was durability. The dacron was far too susceptible to damage from the normal abrasion one encoutners on the average river trip or encounter with an unseen underwater obstruction. In the end I wound up removing the dacron and canvassing the traditional way.
Also be aware that if you use dacron you must use extreme care to fair the hull properly as every high tack head and small imperfection will show through the dacron.
If you go this route I strongly suggest you obtain the issue of Wooden Canoe that has an excellent detailed article by Alex Comb explaining the entire process of covering canoe with dacron. I'm sure Dan Miller can advise you which issue you need to order.

 

[samb]

This shot taken from their video pretty clearly illustrates the problems that I mentioned before with the idea of using ballistic nylon. I guess it's a matter of what level of fit and finish you are willing to accept, but there is no way I'd be satisfied with that level of it on one of my canoes.

Bear in mind that this is a boat with ribs but no planking. I don't know how good you would get it with planking, but it would be better than that.

Sam

 

[Benson Gray]

If you go this route I strongly suggest you obtain the issue of Wooden Canoe that has an excellent detailed article by Alex Comb explaining the entire process of covering canoe with dacron.

The old Wooden Canoe Journal index at http://wcha.org/catalogs/Index-to-Wooden-Canoe.pdf identifies this article as being in Issue number 142 from August 2007 which is available from http://www.wcha.org/store/back-issues in the store.

Benson

 

[Todd Bradshaw]

The lack of planking doesn't explain the big saggy wrinkles along the gunwales. I'll second what Andy said, but I've personally never thought aircraft heat-shrunk Dacron was tough enough to want it on one of my boats, so I have no experience using it as such. One thing to know about Dacron and the other polyesters in comparison to nylons, cottons, and some other fabrics is that the polyesters have much less stretch. This is why it's good for sails and usable for canoe covering, as it will pretty well hold its designed shape when wet or when under pressure.

At the same time, this lack of elasticity has a substantial effect on the fabric's tear strength. In a nutshell, when you tug on a hunk of nylon, the local threads tend to stretch a bit and help each other out, spreading the strain over a larger area than just the point of attack. With Dacron, it is a different scenario. The low stretch tends to cause the first thread to try to take all the strain with very little help from its neighbors. When it breaks, the next thread tries to do the same thing, with the same result. This will then be repeated over and over as the tear expands. This is why I can take a piece of brand new 12 oz. (very heavy) Dacron sailcloth, cut a tiny slit in its edge, grab it on either side of the slit and easily rip it in two. The stuff is hard and slick enough that it isn't all that easy to puncture, but if you do hit anything sharp enough to start a tear, there isn't much there to prevent if from expanding rapidly and substantially. So along with the reduced weight, Dacron also comes reduced ability to hide planking irregularities and lower tear strength compared to some other fabrics. Like just about everything else, it is a compromise which may or may not be the best solution for your particular needs.