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Some thoughts on weight

hairymick01

Well-Known Member
Back to some serious thoughts on weight.

Over the past few years, I have been obsessed with building my boats as light as I could. With this in mind, I researched pretty well into the thoughts of some of the thoughts of the well respected designers of timber/composite,canoe andkayak building. There was a similar train of thought in all of them.

In relation to canoes, the gunwhales, thwartes and breast hooks are the heart and soul of the overall strength and integrity of the hull. Each plays its own part and the combined sum of them is greater than the parts on their own. For what my thoughts may be worth (probably not very much) I agree with this.

Most of the force applied to a thwarte may well be mostly tensional, and a rope tied across the boat might seem adequate. likewise, the forces at the ends of the boat and at first clance, a simple dowell might appear to be sufficient.

Thwartes, are an integral part of a canoe's structure. They do much more than just hold the sides together. They might be enough in flat still water but I think eventually the boat would fail if they were all that was relied upon.

Breast hooks, do much more than simply spread the ends apart. They provide a much longer and stronger gluing point for the sides of the boat and the gunwhales. Compare a scarf joint to a simple end glue joint. I know which one I would rather rely on.

Gunwhales made from western red cedar might well do the job in most cases. Our WRC (toonis australis) has the tensile strength of a pound of butter on a hot day, that is to say, practically none so I would question the wisdom of using it as gunwhale material. It certainly has weight advantages when building a strip plank hull tho.

Paddle craft, in particular open canoes are exposed to a whole raft of different forces, particularly so in moving water. Each and every time one of my boats has failed it has been because I deviated from the designer's plans and recommendations in my efforts to make a light boat. i.e. I have used lighter than recommended fibreglass or thinner ply or smaller or not as many thwartes or minimal breast hooks. Each and every time one of my boats have failed, it has been MY FAULT and I have learnt my lesson well.

respectfully,

Mick