The Carlson program develops panels correctly but that doesn't mean that
those panels are developable.
Let's explain: the development method is simple, the program divides a panel
in a bunch of parallelograms and then unroll them BUT that doesn't mean that
the surface is developable.
A developable surface must fulfill some conditions: a cone is developable, a
panel made of cones is developable but the Carlson program does not check
that.
There is another program with that flaw, Plyboats.
Good programs like Rhino, Prolines, the old Nautilus and many others will
create a developable surface that fills some conditions and can be developed
within certain limits. All the ones I know are based on the Kilgore
algorithm. Through an iteration process they check for ruling lines:
straight lines that are included on that surface and run from one edge to
the other without intersecting. There is more to it but that is the basic
problem. You must create a developable surface first. It is a much more
complicated task than to develop the panel.
A test is to design a hull with some nice curvature at the bow then cut
stations through it. If the sections close to the bow show stations with
straight sides, then the program does not do a proper job because that part
of the panels should be generated by cones.
Over the years I wrote about that in this group several times: the Carlson
program is good if you start with a hull that is developable. It is a valid
tool to scale up and down an existing boat, create patterns etc. It can even
be used to design a very simple developable hull like one with cylindrical
panels, "a la Bolger", all station sides parallel.
Who said you get what you pay for?
--
Jacques
http://www.bateau.com
"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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