Heading Sensor vs. Solid State Compass???

Duane Siegfri

I'm confused with the terminology.

My new chartplotter manual says it needs a Heading Sensor in order to overlay the Radar on the chart.

I'm thinking of using the Airmar 220WX for wind at the top of the mast, especially since it incorporates a GPS and a "three axis solid state compass with dynamic stabilization".

Is "Heading Sensor" just another term for "solid state compass"?  

One other thing: Is a compass at the top of the mast subject to error or wide swings due to mast movement in a sea?  What about the GPS...same question?



SV Perigee

re:  My new chartplotter manual says it needs a Heading Sensor in order to overlay the Radar on the chart.

You may not need to install a dedicated heading sensor; but may be able to take Heading data from your autopilot, if it is available as an NMEA output to be placed on your NMEA-183 or -2000 bus.

Further info: our original 400-series Raymarine autopilot was upgraded to the 'G' specification by the addition of a rate gyro input, specifically a Raymarine "Gyroplus2 SHS" (Smart Heading Sensor).   As I understand it this was necessary because the original fluxgate compass (the black puck) did not by itself provide the quality of heading data needed by the new chartplotter+radar combo, for display in the "heading up" mode.  The heading hold and performance of the autopilot is also improved by the additional of the rate gyro input.

The A/P needs to be powered up for the "Heading Up" mode to be available; when the A/P is off, then only "North Up" display is available.

Hope this is helpful.

SV Perigee, SM#396
On anchor, Sint Maarten

Duane Siegfri

Wow!  Lot's of great information/interest.

I spoke to Airmar today and they told me the compass in the 220WX is the same as the GH2183, which had a great review from one of the sailing magazines.

I also spoke to them about the DX900+ (a transducer that is solid state depth/boatspeed/temperature with no paddlewheel).  I was told that they recommend against anti-foul, but that the unit is inherently anti-foul by material selection...  That sounds a bit hokey to me, but I'm thinking that it's not a big deal to pull it prior to a bottom scrape or every three months to give it a rub.



I should mention that our main GPS sensor and the AIS GPS sensor, both from B&G, came with big warnings that these should not be installed up the mast.  So both were installed at deck level.  

Incidentally, I recall noticing that Amel is now installing what look to be a couple of GPS antennas on deck, forward of the pilot's windshield.  I saw this on either a '64 or a '55 in La Rochelle.

Along the same lines, the Amel-factory Furuno heading sensor that was original to #350 sat at nearly water level in the forward closet opposite of the head.  We now have replaced it with a B&G heading sensor sitting in the same little shelf.  

Finally, the original Amel-factory Raytheon/Raymarine heading sensor is still outboard of the dining table, behind the seat, and just aft of the air conditioning vent, i.e, just above the waterline.  It works very well and still provides reliable heading to the Raytheon autopilot.


SM2K Nr. 350 (2002)
At anchor, Spinalonga, Candia (Crete)