This past summer I sailed from Green Bay east across Lake Michigan to Traverse Bay. There were light to non-existent wind and I used my ST4000+ wheel mounted auto-pilot extensively. On the return trip, the auto pilot started operating erratically, making huge course corrections only about once every ten seconds. The drive motor also got very hot. I dis-engaged the auto pilot and took the wheel for the return trip to my home port in Sister Bay WI.
After reading the ST400+ manual, I recalibrated my compass and checked the various settings to assure I was using the correct "Catalina Cocktail" settings. Still no help. After a few calls to the Raymaring tech support group (generally very helpful) they asked me send in my electronic control screen which also includes the 'course computer'. They returned it and said it checked out AOK.
When talking to one of the tech support guys I asked about my motor and said I assumed it was OK as the motor probably worked or it didn't work at all. He said that it was possible that I had carbon build up from wear of the motor brushes, and that could be causing a problem. He said to use compressed air (electronic air cleaner can) to blow out any potential debris from the motor. I removed the motor and could not believe how much dirt / grit / carbon black I was able to blow out of the motor brush area. After re-assembling, every thing is working OK again.
Use caution when removing your wheel mounted drive motor. Follow the detailed instructions in the manual. If you do it incorrectly, you can twist off the power wires at the back of the motor that are very difficult to repair (speaking from experience here). You have to dissassmble and reassemble in the motor, collars, and sleeves in the right order.
Hope this is helpful to some of you.
Ken Enstrom
2004 C-36 MKII #2199
Tall Rig, Wing Keel, M-35B
S/V Valkyrie - Sail Great Lakes
Interesting find. How much time would you say you have on that drive? I assume that's the newer drive, not the 1st version, which was just a dreadful piece of junk. I have an S1 with the newer drive, much improved, though I'm not sure there's much difference in the motor itself.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
We bought our 2004 boat used in 2009. I assume our autopilot was original equipment. The autopilot system is 'gray' which evidently means (after talking to Raymarine tech support) that it is a later model ST4000+. I don't know how many hours it has on it or how hard it may have been used.
Interestingly I found that a replacement motor (with correct gear on the shaft) from Raymarine costs about $65, but after looking up the actual elec motor number shown on the side of the motor on the internet, it appears you can purchase a similar motor for about $5. (it is mainly used in small rotary hand tools) Not sure how you get the correct gear off of the old motor and onto the new one however. Maybe only a press fit?
Ken Enstrom
2004 C-36 MKII #2199
Tall Rig, Wing Keel, M-35B
S/V Valkyrie - Sail Great Lakes