> I am constructing my 4th wood and canvas kayak. This project
> is an 18 1/2 ft double based on Norman Skene's 1923 Walrus.

> I've never run into this problem before...but I'm sure that it
> isn't unique. I stretched the skin onto the frame 2 days ago. I was
> very pleased with the results. Yesterday I killed the weave with 2
> coats of oil based paint and talcum powder. Last night it was still
> tight and the paint was fairly hard. We had a heavy dew and now my
> 'yak sports an "elephant skin". I am sure (I think) that
> the humidity allowed the skin to stretch and suspect that it will
> shrink (somewhat) when and if the humidity drops. What can I do to
> correct this (I suspect nothing). What can I do to avoid this in the
> future? Apply canvas damp? Only canvas on foggy days?

> Thanks...I'm about ready to break her up for matchsticks!

Before you break her up, put a ``for sale'' sign and a price on your white elephant. Even with sags it is probably worth a lot more than the equivalent weight of matchsticks or toothpicks.

Try using a heatgun or hairdryer on the inside of the canvas to see if it shrinks back when it is heated. If so, you might try coating as much of the interior as you can reach with a coat of paint. Either that or travel with a hair dryer or a blow torch.

George Putz`s book covers that Skeene design. Putz suggests in the text that you paint the skin after getting it wet. The oil based paint goes right on the damp canvas. This sounded strange to me, but maybe you have found the reason behind these instructions. With birchbark and canvas covered canoes, it is common to insert slats of wood between the ribs and the skin. The slats are somewhere around 2 to 3 inches wide by 3/16 to 1/4 thick, and maybe 2 to 4 feet long. These servet to tighten the skin, kinda like shims or wedges. It would add weight, but might be the idea for you if you don't want to pull off the skin and redo it..

Speaking of redoing things. You may just want to pull off a few tacks or nails and restretch the skin ( while it is damp, and at its saggiest). Before you do this, though, let me suggest you head over to the local art supply store and buy a canvas pliers (assuming you do not have one already). I've never seen this tool mentioned in books or articles on building kayaks, but it is commonly used by artists who stretch canvases for painting all the time. The canvas pliers has a wide pair of jaws that grip the canvas, and is built so that it supplies a lot of leverage as it pulls the canvas taut. Now that the oil paint is on the canvas you will NEED that added leverage. For mail-order supply, the first name tha comes to mind is Dick Blick Art supplies, but I am sure there are other artist supply firms on the net. Maybe someone can find a picture of these things.

Troubleshooting: Did you get this batch of canvas from a new supplier? Is it a different lot? Was it previously damp, or `prestretched`? Might want to find out how this batch is different from what worked, and let us know. It might save someone else from a problem.

Best of luck to you with this.

Paul Jacobson