Autopilot problen during missions

Went out testing my baitboat today and need some input:

When I set a waypoint behind the boat and start the mission the boat only operates the rudder but no acceleration happens. With water that is calm it takes forever for the boat to point in the correct direction and then it will start driving to waypoint. Also when it turns after reaching a waypoint it oversteers, stops throttling till it points in the direction of next waypoint then starts throttling again. What can I set to correct this behavior.

Using rover V4.6.1

Using dc motor with esc x1
Using servo to steer rudder