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Raymarine forum - [CA11] Rudder indicator reading incorrectly

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Full Version: [CA11] Rudder indicator reading incorrectly
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Earlier this year I fitted an ACU 300 to my yacht, calibrated it successfully and had it working well for the short trip across the bay back to my mooring. That was back in February this year. A couple of months ago, thanks to a Raymarine forum append I read, I found I could use one of my i70s units to display the rudder position. Apart from configuring the screen, this also included having to configure a small offset (2 degrees) via my Axiom autopilot setup screen so that the display indicator was correct relative to the actual rudder position. So far so good.
Since then, I have updated the software for all the Raymarine components on the boat, using the Axiom MFD software update function which lists all the updates that can be applied. I also updated my Navionics charts (both chart and sonar). Apart from that, no other changes have been made and the autopilot has not been used since the initial trip back to my mooring earlier in the year.

So here's the problem. Yesterday I switched on the instruments to check they were still working and found that the rudder indicator on my i70s was reading completely wrong. With the rudder centered, the display was showing 42 degrees Starboard. I then tried using the Dockside Assistant to configure the autopilot, went through the normal centre, wheel to port, wheel to starboard, centre sequence but then got the error message 'inconsistent values'. I've since tried this several more times and get the same error. I've also checked the sensor but this is positioned correctly and hasn't been interfered with. I removed the sensor linkage and manually positioned the sensor arm to get some readings.
With the sensor arm secured in a fore and aft line it is reading 42 degrees Starboard
With the sensor arm released so its internal spring pushes it as far as it will go in my installation, it reads 4 degrees Port.
Clearly something has gone wrong with either the data being emitted by the sensor, or the interpretation of the data by the ACU 300. Seems to me more than coincidence that this appears to have occurred only after the software updates, but maybe that's just the paranoia of an experienced IT person!
Would appreciate advice on how to address this.

Welcome to the Raymarine Forum Mike,

Is suspect that there is a fault within your rudder reference transducer. Please click here to view a FAQ addressing how to test the transducer.
Hi Chuck

Thanks for pointing me at the diagnostic notes. I'l run those tests when I'm next on the boat.

You're welcome.
Hi Chuck

The reading are definitely way off.

Red to Green: 5K Ohms (+/- 10%) Steady. Mine is around 4K7 so within tolerance.
Red to Blue: Variable no less than 1.5K no more than 3.5K as the wheel is spun hardover to hardover. Mine is 23M with no real change as wheel is turned.
Blue to Green: Variable no less than 1.5K no more than 3.5K as the wheel is spun hardover to hardover. Mine is the same result as the previous reading, i.e. in the mega ohms.

Given that this is a brand new installation and unused, and that there's not much more than a variable resistor in the unit, I'm a bit taken aback by this sudden failure. I hope this is an anomaly?
Anyhow, next step is to get it replaced. What's the process for that?


The rotary rudder reference units are generally quite reliable. Most failures are the result of physical damage. I have reached out to one of our reps in Australia to assist in getting you a replacement rudder reference transducer.
Thanks for helping to get this sorted Chuck.
I'll wait to hear from the local rep..

You're welcome.
I have an update... and a kind of confession to make!
After speaking with the FLIR technician here I was advised to remove the sensor and bring it to him for replacement. When I got the unit home I re-ran the diagnostic tests and was surprised to see that the was now working! Further investigation showed that a cable join I'd made had a dry joint - the downside of doing delicate soldering onboard without my spectacles I guess. So the cable and the connection must have moved after the autopilot was fitted and tested, resulting in the failure.
I've now resoldered the connections, at home, in my workshop and with my glasses on!
The sensor is now working correctly.
Sorry for any waste of your time Chuck.
Thanks for the follow-up. I'm glad that it is now working properly.
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