## 18180Re: Boat Offsets and Stitch n Tape

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• Mar 1, 2002
> I recall reading that Jim Michalak uses the method of joining
> triangles.

It's all based on the concept that the ply doesn't stretch, so the
triangles all stay the same size and shape. Suppose you have a chine
hull drawn with the usual 11 stations (0-10). To lay out the
topsides, you could start with the triangle that has the base at the
chine and rail at station 5, and the peak at the rail on station 6.
The next triangle would have a base at the chine and rail at station
6 and the peak on the chine at station 5. Etc, both ways.

So far as I know, all the fancy software works basically the same
way, except they use a larger number of stations (and/or cleverly
chosen triangles) to cut down the error.

Exercise for the student: What happens when you try this process with
a "non-developable" hull shape? Hint: the trouble begins because the
straight-line length of a triangle side is not the same as the length
measured along the curve of the hull.

Peter
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