Giving the user a GUI means of setting a rudder angle seems entirely wrong for a game at this level. It is just too close to the hardware and demanding of the player's attention when he must also attend to other duties (I'm guessing this advances beyond one ship against one ship ... I am on level 3 of the tutorial).
Fleets of this era (indeed, since Trafalgar and earlier) maneuvered in divisions, usually in line ahead. Divisions, in turn, took up position relative to another division or were told to turn to a given heading.
There have been plenty of games which answered to such a design. It produces orderly (well... YMMV) battles that are easier to command at the high level and a rather chess-like match of position and maneuver.
I would be happy to share a copy of the Royal Navy or the Imperial German Navy's signal books, which provides a good overview of their systems of maneuver and command. They lend themselves to simplification, but you would see that their very nature is quite different than what your design is offering players.