"Brian D" wrote in message news:m9NAb.460002$Fm2.453789@attbi_s04...
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 just got my design for a 20 footer I am building back from the
engineer (who I had go over the design a one time). I designed the
boat in Carlson and was able to shape the bulkheads there. I was
thinking about expanding the panels out and building that way but the
more I read, the more I think I might just get them out the old
fashioned way.
Scotty from SmallBoats.com