Needing electronic compass for Radar (AIS)

[CarinaPDX]

You might have an adequate electronic compass in your autopilot, but maybe not. The older RM compasses are definitely not up to it. The spec to look for is 10Hz (10 times/second) updates, as stated above - slower won't meet Furuno's specs.

I would recommend either the Airmar or Maretron compasses - both provide the required output. I bought the Maretron compass, and wired it into my RM SX-5 to replace the crappy RM one (the old style that has been around forever). Some MFD manufacturers relabel the Airmar as their own, at a markup. Before you buy you should read the manual and see what is required to calibrate the compass. For the Maretron I used a terminal program on a computer to talk to the compass via NMEA 0183 (a bit too technical for some); otherwise it may be necessary to have a display/MFD which can provide the front end for calibration.

Airmar

https://maretron.com/products/ssc300.php

Greg

[IslandHopper]

Originally Posted by sailon46

I am lost with the original post. I have a Garmin 740s still working brilliantly and a Garmin HD18 radar connected to it. No compass needed since it works off the 740s. This Furuno stuff I don't understand, anybody willing to enlighten me.
Thanx,
Ernie on the Mary Jane

Well just going on the specs you are not utilising the unit to it's full capability if you don't have a heading sensor fitted....

https://buy.garmin.com/en-AU/AU/p/13489

To help you avoid traffic on the water, the GMR 18 HD provides MARPA target tracking when combined with a multi-function display and an optional heading sensor. MARPA tracking allows you to track the bearing, course, speed and predicted closest approach of up to ten targets. In addition, like all Garmin radars, GMR 18 HD has self-contained signal processing, which provides you with a more precise, easy-to-read signature.

[chouliha]

Originally Posted by captmikem

Check to see if your autopilot uses a Fluxgate compass, if not you can buy a new or used one pretty cheap. Quick internet search shows a Raymarine Fluxgate for $161.

M

We have a WH autopilot and just contacted owner who said there is no way to pick up signal from compass without opening his sealed box. I am very reluctant to do that.

[chouliha]

Thanks everyone who responded. I may just pass on this extra expense(until we are back in the States again) and just rely on my Vesper Marine Watchmate 850 which resides next to the radar unit to track targets. So far its been terrific. Targets will still show up on radar but not identified.

When we are back in the states I will explore buying a fluxgate compass that will work with the Furuno 1815.

Ahhh more $$ and more gear to install!

Thanks everyone!

Chuck
Mo'orea, FP

[IslandHopper]

Originally Posted by alctel

It's totally fine for MARPA - I used it for that for almost two years. As I said, I wouldn't recommend it for a primary unit for autopilot. What makes it fake?

Read the bottom sentence on the page you linked to....

Simrad GS25 GPS Antenna | SIMRAD

*Please note this product is not suitable for use with MARPA or autopilot systems, this requires a rate compass such as the RC42.

The exact same unit from Lowrance is the Point-1 which states the same "Not recommended for use with MARPA"

http://ww2.lowrance.com/en-au/Produc...t-1-en-au.aspx

For my Lowrance MFD and 4G Radar i use the recommended (read correct) RC42N Rate Compass for the MARPA function, the previously mentioned GS25/Point-1 units are just not up to the task.

[Wayne hoath]

Originally Posted by sailon46

I am lost with the original post. I have a Garmin 740s still working brilliantly and a Garmin HD18 radar connected to it. No compass needed since it works off the 740s. This Furuno stuff I don't understand, anybody willing to enlighten me.

Thanx,

Ernie on the Mary Jane

It’s the AIS overlay that requires the heading I believe. I have an 1835 and it gets the heading from the autopilot. If that isn’t powered on then the AIS signals aren’t overplayed onto the radar screen.

[Kenmonty]

if you are only going to stay at anchor , or in a marina or on the hard a cheap compass will do nicely and you won't experience any navigation problems with your radar heading.........buy a Furuno compass!

[Suijin]

Originally Posted by alctel

It's totally fine for MARPA - I used it for that for almost two years. As I said, I wouldn't recommend it for a primary unit for autopilot. What makes it fake?

Interesting. I have that same unit...removed it and added the rate compass when I switched to B&G Zeus and 3G radar. It may have worked for you, the issue is how well.

At the bottom of that product page you liked to, last line:

*Please note this product is not suitable for use with MARPA or autopilot systems, this requires a rate compass such as the RC42.

[Paul Elliott]

You really want a high-quality compass when using MARPA or radar chartplotter overlay. Fluxgate with rate/gyro/inertial compensation, or perhaps the multi-GPS heading sensor units are what you should be considering.

Back in 2003 or so my Raymarine radar / chartplotter was set up without a compass. Instead it was using the GPS COG as a substitute for heading. That was a dangerous arrangement, because it was wildly in error when we were moving slowly in swirling currents. Our bow was definitely not pointed in in the direction of COG, so ships and other dangers were not shown in the correct location on the chartplotter.

When we were sailing so our actual heading and COG were in close alignment (as was usually the case), then the MARPA and chartplotter overlay were reasonably accurate.

Once I figured this out I quickly installed a modern fluxgate compass.

[DennisRyan]

No compass heading available from your autopilot?

[seandepagnier]

Get mpu9250 or mpu9255. These cost $4 dollars and has all rate sensors. I have nmea output, and the data is as good or better than all what people have suggested.

Originally Posted by Paul Elliott

Once I figured this out I quickly installed a modern fluxgate compass.

There is no modern fluxgate. Modern compass do not use fluxgate, they use magnetoresistors or hall effect.

[KeelMe]

The Airmar H2183-10 and the Maretron SSC300-01 are both top notch compasses for a great price. For a few more dollars you can't beat the Simrad HS60. As for me and my boat I'll stick with the Furuno SC130.

COG is only accurate for heading if your speed is over 10 knots. Even the cheapest heading sensor will greatly improve the accuracy of your chartplotter. That is what the Simrad GS25 is made for.

[sy_gilana]

Originally Posted by boat_alexandra

Get mpu9250 or mpu9255. These cost $4 dollars and has all rate sensors. I have nmea output, and the data is as good or better than all what people have suggested.



There is no modern fluxgate. Modern compass do not use fluxgate, they use magnetoresistors or hall effect.

Can you please expand on this? do you have NMEA, RSnnn, or USB out?

[stnick]

Yes it all needs to be linked to the NEMA network. You want everything talking to everything else. Morgan 38 auto pilot , Garman 741 AIS, depth all Nema

[sy_gilana]

Originally Posted by sy_gilana

Can you please expand on this? do you have NMEA, RSnnn, or USB out?

@Boatalexandra ^