[DG] [DG11] ST7001 Autopilot Not Displaying HDG or COG

[mikeyor]

I have the following Raymarine equipment installed on my Catalina 470 sailboat:

eS98 (master), eS128, ST7001 autopilot with type 100/300 course computer, heading sensor and fluxgate compass, ST60 wind, speed and depth. The ST and autopilot equipment was factory installed during the boat build in 2002

Everything was working normally until two weeks ago.

When I switch on the autopilot the ST7001 is no longer displaying the heading in Standby or a COG if I switch it to Auto. All that displays on the ST7001 are the words “standby” or “ automatic”. The rest of the display is blank except for the rudder reference bars which move normally as the wheel is turned.

On my mooring, with the boat moving around, the MFD shows a heading of 050 degrees no matter what the real heading is as the boat swings around. If I select Autopilot 050 degrees shows up as the locked heading. The boat’s icon on the MFD points to about 050 degrees regardless of the actual heading. If I move the boat along a straight line course the boat’s icon still shows an incorrect orientation but the COG arrow extends from the icon in the correct direction.

I have disconnected, cleaned and reconnected the SeaTalk connections. No change in status. I have not yet recalibrated the autopilot.

I would be most grateful if you could suggest any diagnostics that would help me zero in on the problem. I am guessing, possibly incorrectly, that either the fluxgate compass or the heading sensor may be at fault.

I look forward to seeing your always excellent advice.

Many Thanks

Michael Yorke

[Derek - Raymarine - Moderator]

Hi Mr Yorke

The total lack of Compass heading displayed on the ST7001 control head can be caused by several issues, in addition the apparent locked heading of 050 degrees also indicates a compass issue too.

Firstly select the compass linearisation calibration in the ST7001 set up and go to the section where you can adjust the compass heading to match the current magnetic heading of the boat, in this section it is possible to turn the compass display OFF, by increasing the heading 1 degree at a time by pressing the +1 button from 359 degrees to OFF. If this has happened, then use the -1 button to deselect OFF and the heading should now be displayed on the ST7001 control head. If you are unable to do any of this - then this is pointing towards the Course computer as the source of the failure.

Next, disconnect the fluxgate compass and test as described here. If the compass tests out OK, this also points towards the computer as the cause of the failure

regards

Derek

[mikeyor]

Hi Derek,
Many thanks for your swift reply to my ST7001 problem posting.

Your advice to look at the compass calibration was excellent.
On a breezy mooring with quite a swing today I entered the align compass adjustment mode and found that the setting was OFF (how does that happen?). I set it to ON with the -1 and immediately saw a HDG displayed on Standby. the heading was off by a considerable amount. After the align heading adjustment I saved and went back to standby. The good news was that I now had a heading displayed where previously there was none. I noticed, however that the ST7001 heading was swinging somewhat and differing from the steering compass by 20 to 40 degrees and would then "catch up" for a brief time before wandering off again.

I put the heading differences down to the fact I did not do a seatrial calibration before doing the align heading adjustment. Do you think that would account for large differences between the steering compass and the ST7001?

Many Thanks

Michael Yorke

[Derek - Raymarine - Moderator]

Hi Mr Yorke,

Thankyou for the feedback.

The SeaTrial calibration would now be a good thing to complete, pick a calm day and turn the boat slowly and steadily whilst in COMPASS ADJUST mode, keep turning until the DEV display shows the amount of deviation local to the fluxgate compass has been measured. Note that if you turn the boat too fast at any point and the message FAST appears, then that complete 360 turn will be scrapped and You will need to complete another one.

This process allows the fluxgate output to be measured and 'smoothed' by the computer to give a reliable and steady output, compensated for all local sources of deviation local to the fluxgate. Once this is done and the deviation measured as below 10 degrees, you should find the output is very stable and if cross checked with a hand-bearing compass should be very accurate. Unless the ship's magnetic compass on the binnacle has been swung within the past 6 months, then do not just rely on that as an accurate source of heading.

regards

Derek

[mikeyor]

Hi Derek,
Conditions were ideal today to do the seatrial calibration. I carried it out and the deviation screen showed 6 degrees. I carried out the steering compass aligment and saved the results. I then did four hour trip under power mostly using a stored route. The autopilot displayed a heading that matched the steering compass and it now seems that everything is back to normal.

Do you have any thoughts on what might have caused the autopilot compass display to be turned off? Could it have been a voltage spike?

Thank you again for your help. I have always found the forum to be a super source of excellent advice.

Michael Yorke

[Derek - Raymarine - Moderator]

Hi Mr Yorke,

If there have been no cases of guests onboard having an 'experiment' with the control unit, then the next most likely cause is a voltage spike or brownout.

You should check the battery status, the charging system, other sources of electrical noise onboard which may have triggered this reset, also check out power cables for any loose connections or dirty switch contacts. Also check out this link here for further information.

Kind regards
Derek