I commend you addition of waves and how they work on boats. But how boats move is in need of some larger changes to make a boat feel closer to true life.
I've been driving all types of speed boats for years so here is the main issues.
the turning circle is generally far too limited. A assault boat can turn its motor almost 90 degrees and rotate on the spot. where as duel engines boat turns more like a van.
Inital low end throttle is way too weak. by the models its safe to assume each engine is at least >= 40hp. The effect seen in the game is a slow reverse takes a long time to overcome with a forward throttle.
reverse and breaking is also too weak water is very resistant so simple Idle and turn will stop a boat very fast.
Boats roll allot like a plane when turning at speed. Too much speed causes the boats to either roll over to the outside of the turn as the hull rolls over its own wave or the props will loose traction and the boat will spin flat.
Beaching seriously as long as the prop is free it can usually pull its self off unless the majority of the boat is beached.
TLDR: need tighter turning circles, far faster acceleration and breaking, roll turning at speed and more forgiving over beaching.