If you were have a double-hull I would suggest the piece Capt. Dan was referencing, it's just like that but only six wide. IMO a double hull would not look good, at least not for a sailing ship, especially with the twelve wide. That is just my opinion. Possibly a tri-hull, with the twelve in the center and a six on either side, would look better, it would be the same width as your original idea. Good luck with whatever decision you choose.