Registered users don't see ads

Autopilot: No Rudder Reference

Discussion in 'Ask All Sailors' started by Rick, Feb 13, 2018. Add this thread to a FAQ

  1. Rick


    Joined Oct 5, 2004
    1,027 posts, 17 likes
    Hunter 420 Passage
    US San Diego
    2.jpg 4.jpg 1.jpg 3.jpg Not sure where to go with this one. When I energize ST6000, I get helm showing hard to port. When in standby, no rudder indicator. When I engage autopilot, I get no rudder reference message. If I push engage a second time, auto pilot engages and indicates normal. Wiring on rudder sensor is normal and hooked up to steering quadrant. Any ideas?

  2. justsomeguy


    Joined Feb 20, 2011
    6,798 posts, 1,098 likes
    Island Packet 35
    US Tucson, AZ/San Carlos, MX
  3. jssailem


    Joined Oct 22, 2014
    7,730 posts, 3,058 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Rick. The ST6000 comes in two versions. ST6000 and ST6000 Plus. These units have different calibrations procedures.
    These AP's are made up of: a display, a computer, the motor drive system, a transducer to identify the rudder position, and your boats steering linkage.

    Impossible to guess from the info as to which module is a problem. Here are 2 tests to help identify (at least the electrical side) which of your modules may be at issue.
    Checking the Course Computer

    It may be that the course computer is not outputting enough or any voltage out of the Motor terminals. To see if the course computer is the cause. if you remove the motor connections out of the course computer:

    • and place a Multimeter in the wires place and then press Auto and then make a +30 course change
    • You should see voltage increase
    • Make a -30 course change and again you should see a change in the voltage but the polarity would be reversed

    Also place your Multimeter on the clutch terminals and check that there is a 12v output when in Auto.

    Checking the Rudder Reference Unit

    The rudder reference transducer is the device that measures the travel of the rudder. The course computer watches the rudder reference transducer to see that the drive system is actually turning the rudder. Running the rudder reference transducer beyond the range of the pilot's electronic or boat's mechanical rudder stops, or a total failure of the rudder reference transducer will prevent the computer from seeing any rudder motion. If it sees no change in rudder angle after commanding the drive to turn, it assumes the drive is not responding to commands. To test the Rudder reference do the following:

    1. Looking at your display watch the rudder bar indicator and move the rudder. Does it move as it should?
    2. Does the rudder indicator wobble/move not as it should? If it does it indicates that the rudder reference unit is malfunctioning.
    3. Disconnect from the course computer and then Using a Multimeter cheeck the following,
      • Cable colour ---- Arm position ----- Resistance
      • Green/Red ---- Any position ----- 5k ohm +/- 5%
      • Blue/Green ----- Anti clockwise stop ---- 1.66k ohm +/- 10%
      • Blue/Green ---- Clockwise stop ----- 3.3k ohm +/- 10%

    Should a test fail then that unit will need to be looked at by a Raymarine service agent. Please make sure that you carry out all the above checks.​

  4. Ron20324


    Joined Jan 22, 2008
    6,596 posts, 750 likes
    Beneteau 323
    US Annapolis MD
    My experience would say the link between the rudder and the rudder sensor fell out of the ball joint. It happens to me when someone goes hard over and pops the ball out of the socket.

  5. Rick


    Joined Oct 5, 2004
    1,027 posts, 17 likes
    Hunter 420 Passage
    US San Diego
    @js im thinking the rudder reference unit is working because it indicates normal and accurate helm angles with the AP engaged. Its just not displaying rudder position when in Standby mode. Thank you for the response however, and I will run your simple tests this weekend.
    @Ron Yep everything is intact and connected. Was the first thing I checked. No corrosion, etc and the transducer has power.
    Im thinking a calibration exercise and a multi meter.

  6. jssailem


    Joined Oct 22, 2014
    7,730 posts, 3,058 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Rick. I use one of the new Raymarine AP’s. I used the link to their knowledge database to get you the test procedures and the reference voltages. You may want to check there for other possible ideas should the voltage info not lead you to a solution.

  7. Ken13559


    Joined Oct 29, 2005
    1,917 posts, 72 likes
    Hunter 326
    SG Singapore
    I had same happened to my Autopilot last weekend. I had disengage link arm from rudder to do some repairs work couple weekends. RRU wiring still connected to SPX-5 Course Computer. Upon attaching the link arm and power I get same problem. No indication of RRU travel/angle. Tried pushing buttons to no vial. Finally power off and on again and everything back to normal after system goes thru Start-Up.

Merriman pedestal control head
Finally, an aluminum replacement for this YS Merriman part.
Leaky Lewmar ports?
Start by replacing lens gaskets in stock now
Sail Trim Chart and Guide
When it comes to sailing, as basic as salt and pepper and just as indispensable!
Sunbrella lifesling covers
Any color, fits over existing bag to match your existing canvas.