Do we really need to 'fill' the canvas on a small canoe?

[Howie]

Yesterday I posted a thread about a 13 ft canoe I just picked up (let's call it a Langford). The thing only weighs 50 lbs. A few years ago I restored a 13 ft Old Town 50 Pounder, and it weighed 65 lbs. That's a 15 lb difference! Today I took the rails off the Langford and verified that it is indeed covered with canvas, but it bends somewhat easy in my hand. So what I'm thinking is that the canvas wasn't filled - that they simply painted right atop the canvas.

And I'm wondering, is that such a bad thing? Is filling the canvas critical in all cases? Sure, an unfilled canvas will be easier to rip & tear. But maybe it's easier to be gentle with a 13 ft canoe that only weighs 50 lbs.

On maybe you can 'partially' fill the canvas; maybe just stop adding as much filler, maybe stop while you still see the canvas weave.

I think I remember seeing some threads on filling the canvas recently. When I get time I'll do some more reading. Meanwhile I'd be interested in your comments.

 

[Gil Cramer]

Langford used airplane dope on the canvas. A long, long time ago we stopped at the Langford "factory" on our way to the WCHA assembly in Dorset. The dope smell was quite noticeable.

 

[Maxtoon]

Penn Yan used to have some hulls that they used a synthetic cloth as a covering that was doped on.The Swift was one, and there were others. It was not canvas. You can still buy similar supplies from Aircraft Spruce.

Pilot Supplies and Aircraft Parts | Aircraft Spruce

Aircraft Spruce is a worldwide distributor of certified and homebuilt aircraft supplies.

www.aircraftspruce.com

 

[John Sand]

Skin On Frame boats use paint on fabric, sometimes with filler. I think the old Trailcraft and PBK boats used only paint on canvas.

 

[Howie]

I'm thinking the canvas should be completely saturated with... something, and then followed with Epifanes (or some other mfgr) top side paint. The obvious answer is to use the same top side paint, but greatly thinned, for the first penetrating coat.

 

[Maxtoon]

The point of filling a canvas is three fold:
1. To make the material a membrane that is somewhat waterproof. This coating has to be durable, resilient to abrasion and flexible since the canvas is only stretched in place and will move.
2. To act as a preservative for the canvas
3. To add a smoothness to the canvas to promote lower drag in the water.

Doping synthetic materials like Dacron doesn't need to address rot and the weight of the material is light enough that it is easy to fill. Some modern materials are heat-shrunk in place before doping.