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lumber for skin and frame kayak
By:Paul Jacobson
Date: 3/7/1999, 8:50 pm
In Response To: Timber for skin and frame kayak (Norman Bull)

> I've just got the Greenland kayak plans by Chris Cunningham from Sea
> Kayaker magazine and would like some advice about which wood to use. The
> choices here (Sydney, Australia) are limited compared to North America.

> Commonly available softwoods are Western Red Cedar, Douglas Fir (locally
> known as Oregon) and pine, which is pinus radiata or "radiata
> pine", OK for furniiture and some construction work but often full of
> knots. Also Pacific Maple/Meranti which is very open grained and I
> wouldn't think suitable for marine use.

> Common hardwood is Tasmanian Oak, generic name for a number of eucalypt
> species.

> Any thoughts on what to use, given these choices?

In his book on canvas covered boats George Putz mentions pine and cedar (among others). When I built the frame for my small skin-on-frame kayak (an 11 footer, originally designed as a folding boat) I used the red cedar I had purchased for a strip canoe. The original plans called for ash for the long, straight pieces (chines). Most of them were 3/8 th inch or 1/2 inch thick. Putz had recommended using wood of the same dimension for his 17 foot boat, and slightly thicker for his 18.5 foot boat.

I took that as a good sign that thin cedar would be acceptable, and then I made those chines thicker anyhow. Substituting cedar for ash I used 1/2 inch thick pieces of cedar where 3/8 th inch pieces of ash were specified. When it called for 1/2 inch, I used 5/8ths inch stock. It was easier to get fatter pieces of knotfree cedar than to find a supplier of another species. All I had to do was rip them to MY specs.

This boat uses plywood frame, with notches for the chines to pass through. Since the chines were fatter I had to recut the frames to enlarge those notches. It is simple project, but had I thought ahead, I would have just cut them to size the first time. (When building boats it's: Measure once, cut twice isn't it )

The only area where I was a bit hesitant about the strength of this substitution was in the cockpit area. I am a LOT heavier than the average kayaker, and I feared that I would crack those thin pieces of wood the first time I entered the boat -- so I reinforced the areas on the left and right of the cockpit opening with a hefty chunk of lumber (about 1 by 3 inches in cross section) The added weight is negligible. The added strength is considerable.

Of the woods you have listed, Douglas fir would be my first choice. Second choice would be Western Red Cedar, and that would only be because I have not had experience with the other woods you mention. Ignore the open grain structure of the Meranti. You can seal that beautifully with a single coat of epoxy resin. If the Meranti or ``Tasmanian Oak'' are strong, flexible, and available in long clear boards, try them.

I'd get knot free sections and scarf them into long planks using epoxy and tapers of anything from 1:8 to 1:12. I like to use 1 x 6 stock and scarf the entire board using a table saw to cut the scarf angle. From these long planks I cut my strips.

By carefully rummaging through the stack at the home discount store I was able to find some clear 10 foot lengths of red cedar. I ripped these in half to get boards that were nominally 1 x 3s. Try to imagine, if you will, one end of the original 1 x 6 plank pointing north, and the other pointing south. After ripping each I had two pieces ( A and B) that each had ends pointing north and south. I took piece B and flipped it so that the ``north'' end of it matched up with the ``north'' end of piece A. This kept the parts of the wood with the closest color and grain match together at the joint -- making the joint very hard to recognize.

I put A on top of B, overlapping them about 2 feet and ran the stack through my saw at an angle to create a scarf joint. Since both pieces were cut at the same time the scarf fit perfectly. Since the pieces of wood were a bit over 2.5 inches wide the scarf ratio was about 2.5:24 or somewhere around 10:1. 3 clamps secured the joint until the epoxy set. A few passes with a hand plane smoothed the joint so I could run this long, narrow plank through my saw again to cut the chines. My wood was a nominal 1 inch and was somewhere between 3/4 and 7/8ths inches thick. I cut 1/2 inch wide strips and got chines that were 18 feet long and had a cross section of 1/2 by 3/4 inch (or maybe a bit bigger).

I think I got 5 long strips out of each 10 foot 1x6 I started with, so my materials cost was not too great: Two--10 foot long, 1x6 boards, at somewhere around $8 to $10 each. If your materials are in that neighborhood it is not an extravagant expense to buy one board each of two or three different species and experiment with them.

Best of luck with this. Keep us informed on how it goes.

Paul Jacobson

Messages In This Thread

Timber for skin and frame kayak
Norman Bull -- 3/7/1999, 6:16 pm
lumber for skin and frame kayak
Paul Jacobson -- 3/7/1999, 8:50 pm
Re: lumber for skin and frame kayak
Rob Cochrane -- 3/8/1999, 6:47 am
Re: lumber for skin and frame kayak
Norman Bull -- 3/11/1999, 4:23 pm