[TG] [TG11] SPX-5 Virtual Rudder Indicator Shows Rudder Hard Over

[spencerdd]

Hi Tom,
Thanks for your quick reply although you sound as frustrated as I am! :-)

It looks like the pictures I was trying to upload in my last post didn’t take. I’m reposting them here although they may not be extremely helpful.

Lets set aside the 2013 warranty issue. I was advised that they repaired or replaced the ST6002. The tech that handed me the package when I picked it up may have been mistaken and, based on your comments, he likely was. Nevertheless, the autopilot system failed in 2013 but worked well for the 2014 through to 2018 seasons after the warranty repair… whatever it was. I had the trouble I described for the entire 2019 season.

Answers and further comments:

Q. Can we do useful tests on the boat before May?
A. Yes, however, at present the boat is covered in snow and I have disconnected the batteries for the season. I expect to be able to start meaningful spring work on the boat by late March.

Wheel Drive Performance
During sea trials and normal sailing, I became convinced that the Wheel Drive is working fine although I didn’t measure voltage to the drive whilst commanding turns. I did verify that the wheel drive responded to change of course demands from the ST6002 smartly for the following manoeuvres:
- Small change of course port and stbd using the +/- 1 Key
- Large change of course port and stbd using the +/- 10 Key including repeated commands… i.e. pressing it 4 times resulted in a 40 deg change of course
- Autotack by pressing the +/- 1 and +/- 10 Keys together. I performed autotack manoeuvres to both port and stbd.
- I have never used the “Track” or “Windvane” modes
I am almost 100% convinced that the wheel drive is performing well. When the clutch is engaged, the wheel is solidly locked by the wheel drive and will not turn unless commanded by the autopilot system. I have never observed, felt or heard anything that would suggest to me that the wheel drive is not performing or that there is any slip in the system or undue resistance at the wheel.

Taking Each Component One by One
There are five elements to my autopilot system. Looking at them one by one as I understand it:
1. Fluxgate Compass. It appears to be functioning correctly since it knows the boat is falling off course and correctly reports heading of the boat when the AP is not engaged. I agree with you that it is unlikely that the fault is here.
2. ST6002 Display. It appears to be reporting correct information including vessel heading and locked heading. It is incorrectly reporting rudder position, however this information is fed from the below decks computer. I agree that it is unlikely the fault is here.
3. ST4000 MkII Wheel Drive. It appears to be functioning correctly based on my report above. It responds smartly to commands to alter course and I haven’t observed any slipping or any undue helm resistance. I know you are suspicious of the wheel drive and it may indeed be the problem but I am almost 100% certain that it is functioning correctly and is not the cause of the boat falling off course.
4. Cabling / Wiring. I’m fairly certain the power and signal cables are correctly connected and routed. However, connections are the cause of many boat problems. I’ll recheck every connection when I’m able to do so but I think it’s low probability that the cause is here.
5. SPX5 Below Decks computer. This is the brains of the system and it receives heading information from the fluxgate compass and commands the wheel drive to make course corrections to maintain heading. It also accepts commands from the ST6002 display and reports vessel heading, locked heading and virtual rudder position to the display. This appears to be where the fault lies since it appears to be receiving good heading information and it thinks it is commanding the boat to make corrections as it falls off course as demonstrated by the virtual rudder indicator, however, the commands aren’t making it to the wheel drive. I am fairly certain the the fault lies here.

Based on everything I’ve seen and learned from reading and your useful replies, it appears that this is an unprecedented problem or at least one that you have never seen in 20 years of supporting Raymarine products. If I am reading your notes correctly, and if the problem is in the below deck computer, this fault is unrecoverable / unrepairable and the autopilot system must be replaced.

This would be disappointing as I only got 5 seasons out of it but if that’s the case, better to know and deal with it than continue to troubleshoot an unrecoverable system.

Does this sound about right? I hope you have some other suggestions but maybe not.

Hopefully the picture is successfully attached to this post.

Thanks
Dave