How I fixed our autopilot and saved €2000! (Garmin GHP 12)


"Rudder Near Limit" autopilot problem 

Coming down the Croatian coast aboard our sailing yacht NISI, on our way to Greece, our Garmin GHP 12 autopilot started to loose rudder calibration. It 'thought' that we had the rudder to starboard, when it fact it was centered. Soon we had a message "Rudder Near Limit" and the autopilot was unable to steer. That's when we knew  we were in for an expensive repair.

Our rudder calibration was drifting no matter how many times we turned it off and on or performed the calibration wizards.

Back in Greece, we contacted a Garmin dealer who told us that the unit has gone bad and that those units, made by Jeffa, don't last more than a few years before that problem occurs (ours is 6 years old). Steering hard over either way and going to the limit of the rudder can cause this problem.

"No one told us about the third option: fix it ourselves!"

Our options, as we were told, were two: get a new rudder unit from Garmin at the cost of €2000 plus shipping, or mount an external rudder reference unit for about €300 plus the extra work required to fit it on the boat (about another €500). No one told us about the third option: fix it ourselves!


Our Garmin GHP 12 connected to the rudder

The solution was somewhere out there...

After doing some research on the web, I came across an old post in about someone having the same problem with their Garmin GHP 12 autopilot. There, I learned what problem was, how to fix it and where to get the spare parts to do it myself. The total cost of the repair was €27 and a bit of work.

The offending part was a small 'Rotary Potentiometer', and all it need was to be un-soldered and then solder the new one on in its place (you can find the unit Here).

Tearing apart the autopilot was not a problem, I just made sure I took pictures of the process to be able to remember how to put it back together. This was a quite straight forward task as the unit is pretty well designed.

Alex at work

Access to the autopilot was tight

The only new skill I needed was to be able to un-solder the old unit and then solder the new one, but that was a skill I should have had anyway ( thank you YouTube for your infinite wisdom ).

Once the unit was on my saloon table, it was easy to work on it and to replace the Potentiometer, reassemble the unit and crawl back into the boat stern to put it back.

Autopilot inside

You need to open the unit to gain access to the faulty part (in blue)


The new Potentiometer and the faulty one.

All I had to do was to run the Dock Wizard and the Sea Wizard (you'll need to get access to the Dealer Wizards)

Happy days!

Since then my autopilot has been working fine, giving me the satisfaction of not only having saved a lot of money, but also to learn what the problem was and how to fix it. If it goes bad again in a few years, I now know what to do and how to fix it... and also my single handed days have become much easier.  🙂

Sailing single handed

Selfie aboard our SY NISI

Your Skipper

Alex Fajardo

About the Author

Co-Owner of NISI Sailing Adventures, Alex is an RYA Offshore Yachtmaster Instructor. He has over ten years experience teaching sailing all over the world and a special knack for having fun while keeping everyone safe. 


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