Hi guys! When constructing ships with curved decks, like the Yamato, Scharnhorst, or the Le Requin xebec, how do you determine what shape to cut the deck? It's clearly not identical to the top profile, since the slope would stretch it out some. But it's also not a straight line, so a simple stretch wouldn't work either. Any hints or tips?
What I have done, lay large sheet of plywood on top of hull, trace it. If you don't have the hull, you can work it out using the side view and top view, and by assuming the plywood is thin, and radius of curvature is large. line up the width from the top view with the side view. then flatten the side view, that will stretch the profile to be correct. (easy to do with cad). but if you don't have the hull and are not scratch building it, then it probably deviates from the top view/side view of the plans by a not insignificant amount.
On all the builds except for the LeRequin, I used the top hull outline with an added 1/8" around the edges. The added material let me sand down the subdeck to fit the angle of the hull if needed. Since the top view of most plans show the deck as the highest point of the hull, this works out for the most part. The Requin is a different animal all together. The plan's rib sections did show where the deck outline was ... it would have been very easy to just mark the deck on the rib templates as they were drawn. But I moved the deck edges up 3/8" on the ribs to flatten the deck across the beam. This worked fairly well except for the last 3" of the stern part where the angles really get funky on the rib sections. I could not use the top vew since the hull beam above the deck is so much wider than the deck beam. I did not worry about any distortion (shrinkage) of the subdeck length due to the curve. It is so small of a change that the hull will still fall within the allowed +/- leeway given in most rule sets.
On my kits I don't worry about the additional length. Even though I have a 3-D deck in CAD and could do what Rhino calls "unroll surface" it's not worth my time. I checked it on the Baltimore and the difference was so miniscule that it wasn't worth the effort. Now I just take the top plane view of the deck and generate the parts from that.
I wrote a program to unroll the deck for me, it also generate the ribs, keel, deck all from the hull mesh that I make with Delftship.. On most ships the difference (unrolled vs top view) is barely noticable.
