[CA] [CA11] GyroPlus 2 and Heading error

[rmclaughlinmo]

I'm a relatively owner of this 36' sailboat. I recently replaced an circa 2003 Raymarine MFD and Radar with an eS97 and Quantum Radar. Other, older gear includes an ST6002 autopilot ctrlr, SmartPilot, fluxgate compass sensor, a below deck drive unit (I'm not sure how to ID it..) and several ST60+ displays on SeaTalk. There is also a GyroPlus 2 E12102 with its associated second fluxgate compass.

I was experiencing my Heading readout and vector on the MFD "jumping" back and forth ~30-50 degrees every second or two. It was suggested I disconnect the GyroPlus and its associated fluxgate compass. This has eliminated the jumping Heading output (seems maybe it was getting differing inputs form each unit and was switching back and forth between each?) but I still have a varying difference of 10s of degrees between the COG and Heading when moving at 5-7kts in a straight line in an area with no current. I notice the error seems to vary based on my cardinal direction and am suspicious I have magnetic interference with the fluxgate compass.

(Note too that my radar, while perfectly aligned when it itself is viewed, however when I overlay it onto the chart view, sometimes the return is where it belongs, sometimes it's to the left, and sometimes to the right. Does the Heading output attempt to align the chart "under" the radar returns?)

I have performed the compass/seatrial/swing calibration and come up with 14 degrees deviation. That is 1 degree less than the SmartPilot Commissioning manual says is the acceptable maximum. (I've also used the Heading Alignment to attempt to minimize the "error" but it still varies widely.)

Do my symptoms suggest a likely problem and best next troubleshooting activity?

- Does it seem right to have disconnected the GyroPlus and its fluxgate, or would I be better off keeping it connected and disconnecting the fluxgate connected to the Course Computer? (Both fluxgate compasses are near each other, about 3' apart.)

- Should I relocate the fluxgate compass (now armed with the Gemeco iNstall app recommended elsewhere in this Forum, though finding a new location for it is easier said than done)? When relocating it, how important is being on centerline vs off to one side of the boat or another?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum rmclaughlinmo,

Q1. I was experiencing my Heading readout and vector on the MFD "jumping" back and forth ~30-50 degrees every second or two. It was suggested I disconnect the GyroPlus and its associated fluxgate compass. This has eliminated the jumping Heading output (seems maybe it was getting differing inputs form each unit and was switching back and forth between each?)
A1. Should two NMEA 0183 sources of heading data have been interfaced to the system, then such dithering of heading could quite easily have occurred.

Q2. I still have a varying difference of 10s of degrees between the COG and Heading when moving at 5-7kts in a straight line in an area with no current. I notice the error seems to vary based on my cardinal direction and am suspicious I have magnetic interference with the fluxgate compass.

(Note too that my radar, while perfectly aligned when it itself is viewed, however when I overlay it onto the chart view, sometimes the return is where it belongs, sometimes it's to the left, and sometimes to the right. Does the Heading output attempt to align the chart "under" the radar returns?)

I have performed the compass/seatrial/swing calibration and come up with 14 degrees deviation. That is 1 degree less than the SmartPilot Commissioning manual says is the acceptable maximum. (I've also used the Heading Alignment to attempt to minimize the "error" but it still varies widely.)
A2. Experience has since shown that should the maximum detected deviation exceed 9 degrees, then a more suitable location should be found for the autopilot's fluxgate compass.

Q3. Do my symptoms suggest a likely problem and best next troubleshooting activity?
A3. See my response to Q2. Should continued problems persist and a location for the fluxgate compass be found which yields no more than 9 degrees of deviation, then it may indicate a problem with the autopilot's fluxgate compass (recommend testing the fluxgate compass) or with the autopilot's gyro (try unplugging the autopilot course computer rate gyro's cable from the course computer's circuit board, re-calibrate, and re-align the autopilot's compass.

Q4a. Does it seem right to have disconnected the GyroPlus and its fluxgate?,
A4a. Yes. Additionally, MFDs which are designed to run LightHouse II or LightHouse 3 software do not feature support for the Smart Heading System. Accordingly, these MFDs do not feature user interface options to linearize or align the SHS.

Q4b. or would I be better off keeping it connected and disconnecting the fluxgate connected to the Course Computer? (Both fluxgate compasses are near each other, about 3' apart.)
A4b. Negative.

Q5. Should I relocate the fluxgate compass (now armed with the Gemeco iNstall app recommended elsewhere in this Forum, though finding a new location for it is easier said than done)? When relocating it, how important is being on centerline vs off to one side of the boat or another?
A5. See my response to Q2. It is recommended that the fluxgate compass be located near the longitudinal center of the vessel. It is less important to be centered within the beam of the vessel.