Magnetic vs Electronic Compass

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
P

petdoc4u

Senior Member
Joined
Jan 14, 2016
Messages
134
Location
United States
Vessel Name
EXILE
Vessel Make
HANS CHRISTIAN TRAWLER
If you have added an electronic compass such as the KVH Azimuth, have you removed your trusty magnetic compass ie. the big one at the helm or have you added the electronic compass but left the magnetic compass in place?
-David
 
I installed the KVH Azimuth at my PH helm because there was too much interference for the mechanical to work. I left a matching mechanical compass (my terminology is probably wrong, but I believe both the KVH and what I am calling mechanical are magnetic, its just that the KVH relies on a remote flux gate sensor) on the flybridge. Both also display a satellite compass (Furuno SC-50), which I accept as perfectly accurate. The KVH is much more accurate than the mechanical.
 
Took off the magnetic compass and replaced with KVH Azimuth. Had them in multiple boats, never had a failure and there isn't a place to mount two compasses.
 
MYTraveler said:
I left a matching mechanical compass (my terminology is probably wrong, but I believe both the KVH and what I am calling mechanical are magnetic.
Click to expand...

The slang term that drives the point home is "whiskey compass".

Flux gate compasses are easier to read and can be displayed any way a manufacturer wants...as well as being able to provide NMEA data. Conventional compasses(whiskey compass) have errors and can sometimes be confusing to read. I rarely even look at my compass. I would if I needed to but have all the direction sensing instruments that I need without it.
 
Last edited:
petdoc4u said:
If you have added an electronic compass such as the KVH Azimuth, have you removed your trusty magnetic compass
-David
Click to expand...

bayview said:
I would never be without a robust whisky compass. When everything else fails it still works.
Click to expand...

If you already have one why remove it???
I have both and like the back-up and logic check...
recently noticed the flux gate was being affected by a tool box stored under the galley steps by comparing it's output to others...moved the tool box
 
A swung, properly located (just like a fluxgate requires) and compensated whiskey compass will have few errors and they can be listed on a card. I found mine handy for taking quick bearings on oncoming vessels, though I mostly used my Fujinons for that. My auto pilot and radar/plotter each had their own fluxgate/heading sensors as well. The only non-magnetic compasses I know of are the satellite variety.
 
Last edited by a moderator:
caltexflanc said:
A swung, properly located (just like a fluxgate requires) and compensated whiskey compass will have few errors and the can be listed on a card. I found mine handy for taking quick bearings on oncoming vessels, though I mostly used my Fujinons for that. My auto pilot and radar/plotter each had their own fluxgate/heading sensors as well. The only non-magnetic compasses I know of are the satellite variety.
Click to expand...

Satellite compass? Never heard of such a thing. Besides, a compass is pretty much a waste anymore. Just use one of your GPSs..... way better info and more accurate.
 
caltexflanc said:
A swung, properly located (just like a fluxgate requires) and compensated whiskey compass will have few errors and the can be listed on a card. I found mine handy for taking quick bearings on oncoming vessels, though I mostly used my Fujinons for that. My auto pilot and radar/plotter each had their own fluxgate/heading sensors as well. The only non-magnetic compasses I know of are the satellite variety.
Click to expand...

I was talking about this stuff!!! And there are more than in this article. They are errors endemic to the compass.

Application of Error to a Compass
 
While I still have mag compasses and can actually use and swing one...not sure I have used one in my last 20,000 nautical miles or so.

Last time I steered on one was maybe 1993.

I can see the advantages of something like the KVH....but I wouldn't toss my $500 mag at the helm for one...because I probably wouldn't use it much either.

Everyone has their likes and dislikes...also the cash to add things that are sexier than their predessesor.

Are they critical for primary or backup nav? Only you can decide....:D
 
Seevee said:
Satellite compass? Never heard of such a thing. Besides, a compass is pretty much a waste anymore. Just use one of your GPSs..... way better info and more accurate.
Click to expand...

Actually not in some cases.

Slow speed in reduced vis, the gps ability to give you smooth turn info isn't able to.

You have to turn on a compass or radar in con fines waters....gps turn info just lags too much at very slow speeds.

And every once in awhile, your gps may be very erratic for some odd reason...visit the Navy warship thread....:D
 
Does the KVH Azmuth perform better than a rate compass like a Simrad RC42, Maretron SSC200, or Furuno PG700? The Azmuth would appear to be a rate compass just like the others, except with an integral display.

I really like sat compasses. They are super accurate, provide both GPS and heading data, don't require calibration, doesn't get messed up when you rearrange stuff on the boat, doesn't go nuts when you turn on high power appliances, and give true heading which is required for certain nav devices. The Vector V104 (sold by Simrad, SeaPilot, SiTex, and a variety of others) costs about the same $$ as a good GPS + rate compass.
 
GPS plotter tells you what direction you've traveled from, not where you are pointed to. Bang-head indeed!
 
Seevee said:
Satellite compass? Never heard of such a thing. Besides, a compass is pretty much a waste anymore. Just use one of your GPSs..... way better info and more accurate.
Click to expand...

Obviously never you have never been in a situation where your electronics failed.
GPS goes down, flux gate compasses go down.

A properly compensated (with deviation card) magnetic compass will always get you home
How much experience do you have?
Compass a waste? You have not been far enough and long enough on board to know!
Had a KVH compass and loved it till it went out and had to make a 120nm run on a hand held Bering compass.
Not bashing electronics here I rely on them 99.9% of the time, but just remember a properly installed magnetic compass will always work when everything else goes down
Bone up on your manual navigation skills, if you ever travel further than sight of land you may need them
Good luck and cheers!
 
Last edited:
caltexflanc said:
GPS plotter tells you what direction you've traveled from, not where you are pointed to. Bang-head indeed!
Click to expand...

If, by "GPS plotter", you mean "chart plotter", it does tell you the direction you are headed if it is getting heading information from a GPS-based sat compass.
 
Panacea123 said:
Obviously never you have never been in a situation where your electronics failed.
GPS goes down, flux gate compasses go down.

A properly compensated (with deviation card) magnetic compass will always get you home
How much experience do you have?
Compass a waste? You have not been far enough and long enough on board to know!
Had a KVH compass and loved it till it went out and had to make a 120nm run on a hand held Bering compass.
Not bashing electronics here I rely on them 99.9% of the time, but just remember a properly installed magnetic compass will always work when everything else goes down
Bone up on your manual navigation skills, if you ever travel further than sight of land you may need them
Good luck and cheers!
Click to expand...

Panacea,

We may agree to disagree, but in this day and age a compass is pretty much worthless, unless one needs heading info for other devices like radar, etc.

Years ago, it was a necessity... that's ancient.

I've been boating and flying for over 45 years, and have had the best and the minimal amount of equipment. Before loran and GPS one needed heading and a chart where they plotted a course and boated that course using a compass, and it worked fine. And, yes, I've had numerous failures of equipment and a few total failures and back then the compass was the life saver.

Today with GPS it's dirt simple. We only need to know where we want to go, and the TRACK that is required to get us there. Heading is not necessary at all. Now, if you only have one GPS on board, perhaps you will want a good old paper chart and a compass, and that's fine, if you wish, but I'd bet the majority of us have 2, 3 or 4 gps systems on board, and some are battery powered so if you totally loose ships power (and you have to have a MAJOR problem with that... usually with three batteries and a genset), then use your back up GPS to get you home.

Since Loran and GPS has been out, I have not needed a compass at all (but still required in some situations), and even with a total failure getting home has not been an issue.

I have no problem if one want a fancy compass, just not for me.
 
psneeld said:
Actually not in some cases.

Slow speed in reduced vis, the gps ability to give you smooth turn info isn't able to.

You have to turn on a compass or radar in con fines waters....gps turn info just lags too much at very slow speeds.

And every once in awhile, your gps may be very erratic for some odd reason...visit the Navy warship thread....:D
Click to expand...

Psneeld,

Do you really need a compass to turn you boat? (we're talking recreational boats not ocean liners). True, the GPS can lag, but a good one lags very little and the gps positioning on the chart plotter is pretty accurate.

And, yes, GPS gives track HISTORY, but it does give the track that one needs to make good to get home.

As for the "satellite compass", the satellite is for the GPS portion, you don't get compass or heading info from a satellite... it just ain't there. While these are neat gadgets, do we really need them? The heading info, is still a basic compass, and sure it can be dampened and coupled with gyros to give a lot of info, like tilt and accurate heading. Just don't need it.... at least for navigation.
 
petdoc4u said:
If you have added an electronic compass such as the KVH Azimuth, have you removed your trusty magnetic compass ie. the big one at the helm or have you added the electronic compass but left the magnetic compass in place?
-David
Click to expand...
I have had two KVH Azimuth 1000 compasses on my last two boats. Both replaced the "whiskey Compasses" and were mounted in exactly the same places as the old compasses. They are more accurate , self calibrating & you can see your deviation from your desired course at a quick glance. They also use the old 12v compass wiring. Simplest thing i ever added to my boat and one of the most useful!

On my existing boat, I'm going the same route as soon as the pain of previous additions wears off!
 

Attachments

  • Compass.jpg
    Compass.jpg
    62.2 KB · Views: 126
MYTraveler said:
If, by "GPS plotter", you mean "chart plotter", it does tell you the direction you are headed if it is getting heading information from a GPS-based sat compass.
Click to expand...

MYTraveler,

Just for clarification, the vast majority of chart plotters have NO heading information in them at all. They show position, track made good (history) and desired track to get where you're going (if you set up a route). Some have other fancy features that are handy, but for heading, one needs a compass which can be a fancy remote one with a flux gate and be pretty accurate but for HEADING, not track. And heading is magnetic, not true. We rarely need true, but it's probably a thought to understand the difference, especially if one lives in California. Here in FL and the midwest the difference is minimal. (variation).

Track is the thing that gets us where we are going, not heading. Now, FWIW, they are identical if there's no current, wind or tide, which is not likely.
 
Seevee said:
Panacea,

We may agree to disagree, but in this day and age a compass is pretty much worthless, unless one needs heading info for other devices like radar, etc.

Years ago, it was a necessity... that's ancient.

I've been boating and flying for over 45 years, and have had the best and the minimal amount of equipment. Before loran and GPS one needed heading and a chart where they plotted a course and boated that course using a compass, and it worked fine. And, yes, I've had numerous failures of equipment and a few total failures and back then the compass was the life saver.

Today with GPS it's dirt simple. We only need to know where we want to go, and the TRACK that is required to get us there. Heading is not necessary at all. Now, if you only have one GPS on board, perhaps you will want a good old paper chart and a compass, and that's fine, if you wish, but I'd bet the majority of us have 2, 3 or 4 gps systems on board, and some are battery powered so if you totally loose ships power (and you have to have a MAJOR problem with that... usually with three batteries and a genset), then use your back up GPS to get you home.

Since Loran and GPS has been out, I have not needed a compass at all (but still required in some situations), and even with a total failure getting home has not been an issue.

I have no problem if one want a fancy compass, just not for me.
Click to expand...

Cheers and good luck to you
And yes I've had GPS failures (signal not related to on board equipment)
To each his own. Just want to know where I'm headed when all else fails, guess you have been luckier than I have
 
Seevee said:
MYTraveler,

Just for clarification, the vast majority of chart plotters have NO heading information in them at all. They show position, track made good (history) and desired track to get where you're going (if you set up a route). Some have other fancy features that are handy, but for heading, one needs a compass which can be a fancy remote one with a flux gate and be pretty accurate but for HEADING, not track. And heading is magnetic, not true. We rarely need true, but it's probably a thought to understand the difference, especially if one lives in California. Here in FL and the midwest the difference is minimal. (variation).

Track is the thing that gets us where we are going, not heading. Now, FWIW, they are identical if there's no current, wind or tide, which is not likely.
Click to expand...

Think you need to read up on satellite compasses.

And yes, in low vis, on the ICW when making sharp turns at low speed, nothing beats a compass. Even RADAR has a bit of a lag, but not as bad as GPS.

I must confess...my first post says I haven't used one...well I guess it was more of a work thing where at night or low vis making sharp turns on the ICW. I wasn't steering on the compass..... but would turn to and roll out on the right heading.
 
Last edited:
Panacea123 said:
Cheers and good luck to you
And yes I've had GPS failures (signal not related to on board equipment)
To each his own. Just want to know where I'm headed when all else fails, guess you have been luckier than I have
Click to expand...

Panacea,

Agreed... but if you don't know where you are a compass is worthless. So, if you loose your electronics in the fog, the compass won't save your bacon.

And no, I haven't been lucky. I've examined the limitations and equipment to get the job done, and choose what appropriate to my level of boating to be safe and get the job done. The compass is just not one of those pieces of equipment... there's just way better stuff. Heck your phone is probably more valuable than a compass if you're lost in the fog.

Not to be confrontational, but I love these discussions about compasses, headings, GPS, track, drift, course, etc.... most people have no clue.

Just think for a minute, if you're in the fog and all electrical quits. What's the BEST thing you would want to get you home? And then what are some of the things that will keep you safe?

Probably and IPad and a fog horn!

And if you're in the fog and loose all GPS signals, you'll probably want another nav system... what would that be?

BTW, I've never had GPS totally fail... since it's inception.
 
Last edited:
Most always, I have paper charts out. So a failure of the GPS, and the fog setting in, I would resort to sounder, compass and charts. Speed and time would still be known. Have done it in the past, more work but not so difficult. With radar much easier, but doable without the radar. It is sure nice to have all the goodies working though.
 
Seevee said:
As for the "satellite compass", the satellite is for the GPS portion, you don't get compass or heading info from a satellite... it just ain't there. While these are neat gadgets, do we really need them? The heading info, is still a basic compass, and sure it can be dampened and coupled with gyros to give a lot of info, like tilt and accurate heading. Just don't need it.... at least for navigation.
Click to expand...

Actually, a satellite compass does get its heading info from GPS, although it uses (in the case of the Furuno SC-50) 3 receivers to do it. And the accuracy is about as good as you can get. Better than 0.4 degrees, as I recall.

Seevee said:
MYTraveler,

Just for clarification, the vast majority of chart plotters have NO heading information in them at all.
Click to expand...

Maybe you are right, but I suspect not. The chart plotters I own and have used extensively (Furuno, Garmin and RayMarine) all have the capability, although the units must be configured to take advantage of it. Heck, even my AP takes and displays heading info. I can't imagine why any major manufacturer would not provide that functionality.
 
Seevee said:
MYTraveler,

Just for clarification, the vast majority of chart plotters have NO heading information in them at all. They show position, track made good (history) and desired track to get where you're going (if you set up a route). Some have other fancy features that are handy, but for heading, one needs a compass which can be a fancy remote one with a flux gate and be pretty accurate but for HEADING, not track. And heading is magnetic, not true. We rarely need true, but it's probably a thought to understand the difference, especially if one lives in California. Here in FL and the midwest the difference is minimal. (variation).

Track is the thing that gets us where we are going, not heading. Now, FWIW, they are identical if there's no current, wind or tide, which is not likely.
Click to expand...

Seevee,

I'm not sure what kind of nav gear you are running, but I can assure you that a normal Garmin GPSMAP system definitely displays heading information. In fact, if you will look at the screen, it displays both GPS Heading and Heading (from the N2K interfaced Simrad RC36 rate compass - part of the AP26 Autopilot) and both can be configured to display direction True or Magnetic. This is a very common setup.
 

Attachments

  • GPSMAP 740S.jpg
    GPSMAP 740S.jpg
    105.3 KB · Views: 55
LarryM said:
Seevee,

I'm not sure what kind of nav gear you are running, but I can assure you that a normal Garmin GPSMAP system definitely displays heading information. In fact, if you will look at the screen, it displays both GPS Heading and Heading (from the N2K interfaced Simrad RC36 rate compass - part of the AP26 Autopilot) and both can be configured to display direction True or Magnetic. This is a very common setup.
Click to expand...

Larry,

You have a compass input and most GPS maps don't. You only get heading from a compass... nothing else. I'd bet that 99.9% of the GPS maps out there do NOT have heading input. It does not come with the unit.

I have a Garmin 4208 and 740s.. neither have heading.
 
Seevee said:
Not to be confrontational, but I love these discussions about compasses, headings, GPS, track, drift, course, etc.... most people have no clue.
Click to expand...

Seevee said:
Larry,

You have a compass input and most GPS maps don't. You only get heading from a compass... nothing else. I'd bet that 99.9% of the GPS maps out there do NOT have heading input. It does not come with the unit.

I have a Garmin 4208 and 740s.. neither have heading.
Click to expand...

That is rich, coming from someone who thinks most people have no clue. When you are in a hole, stop digging. Satellite compasses do, in fact, provide heading information (very accurately), even when stationary. And all the major chart plotter brands accept heading information -- it comes in as NMEA data.

-- Not to be confrontational :)
 
Last edited:
Quote "And if you're in the fog and loose all GPS signals, you'll probably want another nav system... what would that be?"

A magnetic compass and my wrist watch will take me home. If I really wanted to be old school ID even take an ADF. It may suck somewhat but it works unless you have no idea where you are when your electronics fail. Pay attention!
 
You must log in or register to reply here.

Similar threads

RT Firefly
Magnetic compass
2
Replies
47
Views
3K
Hippocampus
H
R
Build quality
Replies
7
Views
696
Choices
C
Mark Laurnen
Simrad AP with Furuno plotter
Replies
7
Views
409
Pascall
Pascall
man7sell
Updating my electronics units
Replies
15
Views
2K
rgano
rgano
Ken C
Replace old electronics with simple
Replies
14
Views
1K
lwarden
lwarden

Latest posts

Back
Top Bottom