I had a Raymarine ST6001 autpilot installed on my boat last season an had repeated problems with it holding a course. At trolling speed for the most part, the boat would hold it's course. But on occaision at trolling speed, after a few minutes the boat would turn hard to starboard. At cruise speed (3500-4000 rpm) The boat would almost always after a few minutes on autopilot turn hard to starboard with one occaision throwing a passenger over the side. Does anyone know what the problem is what the fix is???