Just built my first large ship with 1 large mast, 1 fore bit, 1 aft bit, and a helm. Nothing special. And when I try to take the helm, it gives me an error about it requiring either sails or an engine. The mast is flush with the ship's surface, so it should work.
Also, can anyone explain why the base part of the ship is surrounded in these sparkly lines as if it's not really there?