The screw is controlled purely by the throttles on US boats. If you're steaming ahead and want to stop or go in reverse, the ahead throttle is shut and the astern thotle is opened. This is done simultaneously, in a very smart and military manner! The kid on the wheels is usually a pretty sharp dude, even if he is an Electrician's Mate!
Controllable pitch screws are not used by the USN for many reasons,SubSafe and arrangement issues among them.
"If you ignore the problem long enough, it will go away. Even flooding stops eventually!"