When we are on autopilot, and the waves get over 1.5m and are not directly on the beam, the following happens:


1. An autopilot alarm goes off accompanied by a ‘No Rudder Response’ message

2. The dog rises from his slumber, barks and starts running madly around the boat trying to find the cause of the beeping

3. The autopilot switches off

4. Panicked people start diving around the cockpit trying to regain control boat control

What is that beeping thing?!!??!!


We have a single NAC-3 autopilot running a Jefa steering arm with an RF25 rudder sensor. The problem, however, turned out to be none of these, but was a configuration issue on the Scheiber electrical system. 

Our diagnosis of the autopilot issue took several months:


1. We did the dock based calibration of the autopilot. No change

2. Garcia ‘fixed’ the problem. Based on the boats track we suspect they ran the dock and sea calibration of the autopilot. No change.

3. Garcia contacted French Navico (B&G provider) who suggested changing some autopilot configuration parameters. No Change. 

4. We contacted Navico UK (brilliant service & knowledgeable people).  Over the phone analysis suggested a slipping clutch on the Jefa steering unit could be the culprit. Jefa confirmed it was not slipping.

5. We finally worked out that the voltage getting to the NAC-3 autopilot dropped as soon as it attempted to move the Jefa steering arm. The NAC-3 didn’t have enough power to move the Jefa arm, detected that the rudder hadn’t moved when instructed, and chose to give up and go home.

Steering components require smaller agile person access.

The power to the NAC-3 comes from a Scheiber Bloc 9. Its not hard to open these things and with a multimeter we could confirm there were lots of volts (14) coming in to the Bloc. We measured the output voltage which was an okish 12.5V. But when the autopilot was engaged and attempting to engage the Jefa arm we could see the voltage drop from 12.5V to 3-5V.

The Bloc 9 for our autopilot was in the tech room near the inverter/chargers.

We moved the NAC-3 to another port on theBloc-9 and it worked fine with no voltage issues. It seemed like the output slot was fault.

We later discovered that the ‘faulty’ slot had the ‘Soft Start’ option turned on and this was causing the drop in voltage. This option can be selected on the Navicolor display. Once reconfigured, the original port worked with the autopilot.

We learnt that:

  1. Always check the Scheiber configuration if there is a hint of an electrical issue (or not)
  2. Its simple to open the Bloc 9 and test voltages with a multimeter
  3. Neurotic dogs do not like boat alarms