[CA] [CA11] St4000+ tracking Garmin MFD

[JDGALE0070]

Autohelm steers in auto mode fine. When put in track mode, Autohelm sees nmea 183 commands and asks to advance to first waypoint. Soon after operator confirms track, autohelm makes initial course correction but then seems to hold the initial heading it’s provided and does not correct for cross track or other heading info provided my mfd. I have confirmed that cross track and other heading information is visible on autohelm data pages. I have tried using NMEA 2000 to seatalkng cable and Raymarine seatalkng to seatalk bridge running latest software too ( with nmea 183 disconected), In that instance all autohelm wind and depth data appear on mfd, but the tracking result is the same and auto route from Garmin MFD does not pass waypoint data, but regular track data is passed. Any ideas?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum JDGALE0070,

While having a correctly aligned autopilot compass is not necessary for an autopilot to operate in Auto (point and shoot) mode, it is necessary for the autopilot compass to be correctly aligned to properly support operation in Track mode. When the vessel is operated in the absence of current at the cardinal headings at a constant heading, do the system's heading and COG value match? If not, how much do they differ by? Additionally, there were several versions of software released for the ST4000+, some of which specifically addressed performance when operating in track mode. Which version of software is installed within your ST4000+?

[JDGALE0070]

The autopilot compass agrees pretty closely to the magnetic heading and the MFD heading the total variance between the Magnetic and Fluxgate is about 2 degrees at dock with a known heading, while underway the MFD report GPS headings that vary between 5-8 degrees depending on seastate. The software version level is 11.

[Chuck - Raymarine - Moderator]

JDGALE0070,

One option may improve the reported operation in track mode:
- change the Response Level to 2 ... this decrease deadband.

Based the other information which you have provided, all else appears correct with your autopilot. The autopilot will limit XTE and if it becomes too large will report that the XTE is too great.

[JDGALE0070]

Thanks for this idea, I’ll give it a try...BTW is there a documented deadband error in feet or meters that this setting effects (e.g. setting 1 has a tolerance of 100 feet to port or starboard of the course and setting 2 is 50 feet) or is it a relative setting?

[Chuck - Raymarine - Moderator]

JDGALE0070,

Q. Is there a documented deadband error in feet or meters that this setting effects (e.g. setting 1 has a tolerance of 100 feet to port or starboard of the course and setting 2 is 50 feet) or is it a relative setting?
A. Negative. It is a relative setting.

[JDGALE0070]

Final question on this topic I think, what is best practice or required configuration of the MFD heading source. It has options to use GPS heading, magnetic heading (supplied by NMEA 2000 and my st4000 is supplying that through appropriate bridging devices) or both... another weird Garmin option I think....I assume that for autopilot tracking functionality, both devices should refer to the same heading source...but I’ve learned not to blindly assume anything about these devices!

[Chuck - Raymarine - Moderator]

JDGALE0070,

This is a better question for MFD's manufacturer. Raymarine MFD's will most often be configured to use heading data from the system's magnetic north seeking source should the source be operational, properly calibrated, and accurate. The ST4000+ autopilot is exclusively designed to utilize heading data derived from the fluxgate compass which has been interfaced to the ST4000+.