Boat Building Forum

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form spacing

: Strip building is not my thing, but it looks pretty obvious to me
: that you do not have enough forms. To big a gap between the ones
: you have. But I could be wrong.

Or you could be right. Modern kayak plans tend to have forms spaced evrey foot, while canoes designed 30 and more years ago might have forms spaced every 18" or 24". There were not a lot of strip built kayaks back then to compare the designs to, but as I recall, David Hazen's book had widely spaced kayak forms, same as for his canoe design.

On the other hand, you can define the curvature of many hulls with just 1, 2 or 3 control points, plus the ends, and you really only need to have forms at those points. If your strips are uniform they'll bend evenly and fit the proper curve. Yost does this with his aluminum frames--the aluminum tubing is very uniform in its ability to bend. While he has 5 to 7 frames in most of his designs, a lot of that is for structural support against water pressure. The shape of the hull is pretty much established with the center form and the forms closest to the ends. In greenland design, the boat's shape is taken from the curve of the sheer, or gunwale--and that is defined by the center thwart and just a couple of other thwarts. The ribs follow that shape.

As I see it, when curves are simple, forms can be spaced widely. but in areas where the curvature makes a rapid change, the forms must be spaced closely. It is possible to build beautiful boat with fewer forms, but I think most designers have simply gotten in the habit of using more and closely spaced ones.

Just a thought.