Heading input for 1815 Radar

[Aquarius]

Hello. I am restarting a topic that I wrote about 2 years ago. I installed a Furuno 1815 radar and GP 39 GPS unit two summers ago. I have a magnetic heading sensor that controls my auto pilot and I channeled the input to the radar.

I have a small boat with a single inboard diesel. My magnetic heading sensor is not accurate. I suffers from up to 20 degrees deviation due to the disturbance of the magnetic field as it "curves around" 1100 lbs of iron in the center of my boat. The Course Over Ground (COG) from the output of my GPS is spot on when my boat is underway. If I use the waypoint appearing on my radar screen, it takes me in the wrong direction since the radar screen waypoint is based on course and distance determined from my magnetic heading sensor. Needless to say, my true trails ect are equally inaccurate. In short, I do not get the full capabilities from my radar due to inaccurate heading input.

Are there ways to get an accurate COG input as a substitute from a magnetic heading sensor? A Gyro Compass would be the best but that is of course out of the question. I have heard of the "Satellite Compass" which to me sounds like heading input from another GPS. Would this be a reasonable solution for my situation? Which Furuno product is best for this?

Is there anyway that my current GPS COG output can be converted to heading sensor input? That would be the best solution (easiest and most cost effective) to my problem.

Thanks for any input that you may have.

 

[Johnny Electron]

Are there ways to get an accurate COG input as a substitute from a magnetic heading sensor?

No, the items that require heading must have real heading data and it can not use COG as a substitute. Metal boats or boats where fluxgate units don't work well; a good SAT compass like the SCX21 is normally what is needed to provide good heading.

Is there anyway that my current GPS COG output can be converted to heading sensor input?

There might be such devices available on the market. Ultimately COG is not valid under 3 knots and no matter what will still offer problems if converted. Real quality heading is what is needed.

 

[Aquarius]

Jonny, Thanks for the reply. It looks like about $1200 for that sat compass. That would probably solve the problem if I can find a place on the hard top for it and dig up the funding for the purchase and install. I find it hard to believe that messing with another magnetic heading sensor would improve the situation. I can't do anything about the magnetic interference from an all iron engine.

Being an engineer I get a little obsessed with accuracy. I like things to work the way they are supposed to work. Perhaps someone else with a single diesel engine 28 ft or so plastic boat can chime in with similar experience. Hopefully, eventually I will get this thing right.

 

[gtstang462002]

The SCX20/21 compasses are not magnetic compasses. From my basic understanding of their operation, Johnny can correct me if I am wrong, they basically utilize 4 highly accurate GNSS sensors on each corner of the compass and correlate a heading based off the position of each sensor. This is why they are accurate regardless of any magnetic interferences that may be around. They also contain a heaving, pitch and roll sensor that will smooth out the bottom on your sounder display also.