Hi kpj1,
As saltydog said, you will have better luck with precision steering disabled. For one thing, it allows you to return the throttle to stop, or the steering wheel to amidships, quickly by just pressing one of the arrow keys. This is useful when you are about to lose it on the Jetski.
It is best to steer with the mouse on the wheel for small corrections, especially on the Jetski.
For the larger boats in a heavy sea, you can often just tap the left/right arrow keys for course corrections.
Enjoy!
Marty