Many ships have a main deck that is anything but flat, ie most Japanese ships of the WW2 period with their notoriously wavy deck lines. Other just have a deck line that is shaped like a shallow bow. High at the bow, dipping down amidships and rising again at the stern. How do you make a wooden subdeck and deck do that? Steam it? Multiple sections? Damn it all and make the decks flat?
Both. For ships like the Verite and Erin which had a slight crown from beam to beam, I built them flat upside down on the building board without the crown. My latest technique for curved deck ships is shown in the Omaha CL build thread. To get the curve set, the deck/subdeck was laminated from two pieces of 3/16" plywood. The first 3/16" layer was flexible enough to curve and tack glue into place on each rib. Then a second layer of 3/16" ply was laminated in to set and stiffen the deck curve into place. Once the hull bottom was glued in place, the entire ship was stiff enough to prevent the curved deck from warping the frame and keep the graceful deck slope from stern to bow.
I've seen a few ships with flattened hulls, and it is quite ugly. On the other hand, you don't need to perfectly duplicate a ship's curves in order to look good. When making a wooden hull, you can often section the subdeck one or more times. For example, my battleship Mikasa has a rising bow, a flat middle section, and a rising stern. I built the ship in three sections, then joined them together. Each section is flat, but the net effect looks like a beautifully curved hull. For other ships, like the South Dakota and Richelieu, you can do something similar. Technically it's supposed to curve upwards, but you can cut a straight, upward-sloping line and nobody will notice. Fiberglass hulls are already curved, you just need to bend your subdeck and glue it. And RichelieuBB described an excellent technique for the more curvy ships.
I had my first run in with the rising deck line of the bow. It is my first wood hull and it is the USS Commencement Bay. She is an escort carrier. I at first used a 1/4" subdeck with a 1/8" deck. I ended breaking the keel before discovering the rise of the deck in the bow. I ended up cutting slots in the 1/4" subdeck and fixing the keel. Looks good and rise is now evident. I guess, I shouldn't have used high quality aircraft grade 5 ply plywood. I would try using 1/8" for both decks and still cut slots beam wise to achive the rising bow line the next time. Kim
