Comment by akavel

As others mention, show the keys in the interface. It took me a while to discover accidentally, by pressing space, that I can trim the sails. You could make a graphical guide, showing a ship with arrows around, some arrows attached to the hull with keys responsible for turning the ship, some arrows attached to sails with keys responsible for trimming them. Yet another key by the cannons fire to show which key... umm... fires the cannons...