I was wondering if anyone has a good solution for going from a molded hull form to a riveted hull form.
If I have the molded line (red), the exposed edges of the plates (green), thickness of each strake and know whether the the edge is on the inside or outside of the molded line, and amount of overlap, is there some tool to build a hull shell?
My understanding is “molded lines” for most ships are to the outside of the frames. The frames are built based on the lofted lines, and then the plating is applied. To the extent the plating fits tight against the frames the molded lines would also be the inside of the plating.
I have modeled lapstrake wood hulls but not riveted metal hulls. For the lapstrake hulls I start with the inside of the bottom strake. OffsetSrf (with loose option) to obtain the outside of the plank. Then work my way up the hull by modeling the inside surface, OffsetSrf for the outside surface, and then the next strake.
What will the Rhino model be used for?
That is the simplified description. The molded lines are are really the reference lines that define the shape form of the major structures of the ship.
Normally, the molded lines for deck go under plating. But, if the plating thickness changes, you’d want the deck to be level on top. In some areas, the plating goes under the modeled line.
In the case of a riveted hull, the plating can zig-zag across the molded line because of overlaps. Ship designers appear to have taken artistic pride in how many variations they could come up with. In some cases adjacent strakes may be flush and have a cover plate. In other cases a strakes can alternate such that one is along the molded line on the inside and the ones above and below are on the outside. In other cases, they just zig-zag.
This is why riveted ships were built from the shell in. The frames were templated to the hull shell as the shell was constructed. Consequently frames invariably have jagged edges. This is also why the actual measurements of large riveted ships deviates from their designed measurements by several inches.
The model will be used for illustration.