client/ server rotational values desyn with actor speed?

I have an actor that is a ship, with a child actor that is a helm. Characters interact with the helm, the server authenticates the player and the player is then given control over the steering wheel rotation. The steering wheel rotation is then set by input and a repnotify.
If the ship is not moving, or in single player, everything works as expected. all of the stations (helm, sails) are useable and work properly in multiplayer. If the ship is moving about 25% of its speed, the steering wheel values desync, the server reports a different value than the client, and the gap varies and slides around. If I am moving anywhere above 50% of the speed of the boat (not that fast in game terms), the server completely desyncs and stops reporting ANY rotational value change at all. Only the client registers a change.
Any help would be amazing.
Thanks in advance.