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Re: Skin-on-Frame: Too light? 11 lb Canoe.
By:Paul G. Jacobson
Date: 10/20/2009, 9:56 pm

: Just tested out my new canoe, its a temporary boat, the plan is to section it
: and turn it into a folder, but before I went to all that work I wanted to
: see if the hull was right, and the parts strong enough.

Since it works, you can probably lighten the parts a bit even more. Personally, I'd like to see the keel a bit more robust than the gunwales, or, have a few more frames or ribs to transfer stresses from a thin keel to a strong gunwale set.

: The frame is constructed of western red cedar, with plywood cross sections.
: The plywood is also temporary, I am planning to gluelam the final ribs out
: of veneer strips.

Hey--Plywood works and the weight is not bad, You can stick with it. Or, try steam bending some ash.

: Frame weight is 10 lbs, including the plywood cross sections (which I think
: are about 2 lbs).

: The lumber is about as cut down as I dared, 1.5"x0.75" gunwales,
: stringers are 0.75"x0.5", and keel stringer is
: 1"x0.75".

You could probably get the gunwales down to the same dimension as the keel. Tying the gunwlaes and keel together with your frames or ribs creates a very strong bridgework. the stringers support the skin away from the frames (ribs) and could be thinner than what you have, too. I've seen 1/2 x 1/2 and 1/2 x 3/8 stock used for stringers. You can use a pair of them or three to a side for better skin support at about the same weight as what you have.

: Overall dimensions are 11' x 27", and the design is my own, though
: really I just built something that looked canoe like.

Judging from the pictures it seems to fit your body pretty well. You don't have a lot of "freeboard", though. Freeboard is the amount of the boat that is above the water. On an open canoe you usually want 6 inches at a minimum. anyting less catches even small waves and you spend more time bailing than paddling.

You've wrapped the frame and covered over the top of the canoe. That would usually be called a covered canoe, a decked canoe, or a kayak. Whatever name you use, by limiting the amount of open area on top of the boat you keep out waves and splashes. That is a big advantage, and lets you get away with less freeboard. It gives you a lower boat which doesn't catch as much wind.

I'd capitalize on this by putting in a real deck. Consider adding a deck chine running down the center. You can support it by the same frames or ribs that tie the keel to the gunwales, or make separate supports to tie the deck chine to the gunwales. Or, if you are hiking with the boat, consider using your pack to support a deck. Raising the center helps to shed water.

: All in all it feels pretty strong. It sits with the keel hogged on land, but
: straightens out when you sit in it. I think I am going to cut some up
: sized hull stringers, the current ones flex a little too much.

Double check this with a sandbag weighing about what you expect your pack and ger to weigh.

: Has anyone had experience with how red cedar this thin holds up? Or is this a
: little too light?

Right now it works. You are using solid wood. If you are going to be cutting your stringers, chines, keel and gunwales into shorter pieces, and the rejoining them with some form of connecter then you'll need to retest to see how much strength you are giving up to the connector.

You can increase the strength of the wood with a small increase in weight by wrapping it with a layer of glass cloth soaked in epoxy resin. Spiral wrap a long, thin strip of glasss cloth, or lay up cloth straight in line with the wood.

You can also make your own fiberglass ferrules for joining the shorter wood strips you'll use for your collapsible version.

So far it looks pretty good. have fun playing with all your options on this project.

PGJ

Messages In This Thread

Skin-on-Frame: Too light? 11 lb Canoe. *Pic*
dbynoe -- 10/18/2009, 10:28 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe. *Pic*
Aaron H -- 10/22/2009, 3:06 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe.
dbynoe -- 10/23/2009, 1:30 am
Re: Skin-on-Frame: Too light? 11 lb Canoe.
Bill Hamm -- 10/23/2009, 11:48 am
Re: Skin-on-Frame: Too light? 11 lb Canoe.
frankp -- 10/22/2009, 12:35 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe.
Paul G. Jacobson -- 10/20/2009, 9:56 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe.
Steve Rasmussen -- 10/19/2009, 10:34 am
Re: Skin-on-Frame: Too light? 11 lb Canoe.
Charlie -- 10/19/2009, 1:52 am
Re: Skin-on-Frame: Too light? 11 lb Canoe.
dbynoe -- 10/20/2009, 1:10 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe. *Pic*
dbynoe -- 10/18/2009, 10:29 pm
Re: Skin-on-Frame: Too light? 11 lb Canoe.
Charlie -- 10/19/2009, 11:24 am