Keep in mind that shell plate expansion (what you are doing by hand and with
software) is one of the more challenging parts of a hull design program.
Even programs produced for more professional work, such as Rhino 3D and
ProSurf, do not do a perfect job until you learn the ins and outs and tricks
of the trade to make it work right ...a key one being tolerance management.
It's very easy to create an issue with tolerance stacking, especially in an
iterative calculation like what shell plate expansion uses. You can nearly
always tell which designers actually built the boat they sell plans to or
not by how large the errors are in the panels. I've heard of errors as
large as 5" in a 20' boat for example. Another key is management of curve
complexity. In a developable panel, this primarily refers to the
combination of rate of change of curvature and also the tightness (radius)
of the curves. To be accurate in such areas, the triangulation (what the
software is doing) either has to be very tight across the board or vary as
it goes. You'll find that every program is 'pretty good' to a point, then
once beyond that particular constraint, the accuracy drops off. Try
designing a boat with more gentle curves and see how it works out. If the
software allows you to define a measurement tolerance, then lean towards
making it tighter, not looser. You can loosen the specs after you have a
finished panel that works, but don't do it in the calculation stage (kind of
like not rounding off in precision until you report the final answer with
the right number of significant digits.)

So, the bottom line is: take heart, your experience is not out of the
ordinary. Look into the settings that Carlson makes available and continue
to try different approaches until it all comes together.

Brian

"William R. Watt" wrote in message
...
Has anyone sucessfully built a boat out of unfolded panels from this hard
chine design program?

I set up stations and made a cardboard scale model of a boat by wrapping
the cardboard around some frames, marking, unfolding, and cutting. Then I
put the offsets into the Carlson program and used the "Patterns/Nesting"
feature to arrange the panels on sheets of plywood and print out points
for hand plotting. I plotted and cut the panels from cardboard, same scale
as the model, and taped the cutouts togehter sticth-and-tape style. The
result isn't the same as the model. There is a big gap at the stem, the
topside panels are 25% wider, and the it just doesn't fit the frames.

(I've been back seeing if I can alter the offests to get a better fit and
find the auto spline makign S-curves in the keel at the stem. Very
strange.)

Am wondering if others have got good unfolded panels from the program.

(The boat is the 15ft solo cruiser design I've been documenting under
"Boats" on my website.)


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