David,
Seriously, although the smaller boats can be driven like bumper-cars using the left & right keys with short taps, true steering of large vessels such as Titanic is best done by turning the wheel with the mouse. If you click on the wheel and drag the mouse away from the center, you can work with a large diameter circle and set the rudder angle to within a degree. You can also return the wheel to amidships rapidly by double clicking the hub of the wheel.
Probably very few users ever acquire, or attempt to acquire, skill in accurately steering Titanic, or other large ships, with any precision.
If, for example, a mission requires you to make a turn in dense fog at a rudder angle of 12 degrees, you might find it difficult to do other than with the mouse.
Good luck,
Marty