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Old 09-16-2016, 07:32 PM   #21
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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.
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
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Old 09-16-2016, 07:38 PM   #22
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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.
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.
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Old 09-16-2016, 07:39 PM   #23
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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
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.
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Old 09-16-2016, 07:51 PM   #24
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Old 09-16-2016, 07:55 PM   #25
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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.
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Old 09-16-2016, 08:05 PM   #26
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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.
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.

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MYTraveler,

Just for clarification, the vast majority of chart plotters have NO heading information in them at all.
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.
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Old 09-16-2016, 08:19 PM   #27
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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,

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.
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Old 09-16-2016, 09:13 PM   #28
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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.
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.
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Old 09-16-2016, 09:49 PM   #29
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Not to be confrontational, but I love these discussions about compasses, headings, GPS, track, drift, course, etc.... most people have no clue.
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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.
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.

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Old 09-16-2016, 10:00 PM   #30
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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!
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Old 09-16-2016, 10:06 PM   #31
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If the North Koreans launch something, as I am happily negotiating a fog bank out on the lake...

I don't expect Uncle Sam will leave those GPS signals functional with an incoming...

That's just my luck... a boring old fashioned compass will remain in a place of honour up there on the horizontal at the helm.

Your mileage may vary...

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Old 09-17-2016, 12:31 AM   #32
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Do y'all even know what a heading is??? A course? Magnetic??? True???? I think that is the issue with this discussion. There are some semantics involved.
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Old 09-17-2016, 02:56 AM   #33
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Old 09-17-2016, 03:22 AM   #34
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Do y'all even know what a heading is??? A course? Magnetic??? True???? I think that is the issue with this discussion. There are some semantics involved.

As I read the last 20 comments this seems to be the best comment. There are about 20 NEMA sentences possible for either IN or OUT

Most recreational boats I have been on (either as guest or to help a new owner) have gps operating as out of the box with little (or none) adjustments to tweak it.

The gps heading output is adjustable from wildly responsive to dampened down so much it is seconds or half a minute delayed in response.

But the use of instant heading versus dampened is taken advantage of differently when at high speed versus slow speed. But I have not seen a GPS unit that is easily switchable between the two ( and fewer operators who know the difference)

Have you ever seen a boat on a ais equipped plotter with its heading gyrating wildly? That is a boat that has NO dampening set up in GPS heading data. Or it could be a boat with the GPS antenna with a really highly mount (mast head or high whip). Conversely a boat on a plotter with a heading that has already changed course and is still showing the original heading? That is over damped and is too slow.


The mentioned 'satellite' compass' are simply GPS heading sensors. They work great for heading. But I'd rather have a standalone fluxgate or gyro. And a GPS for cmg.
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Old 09-17-2016, 05:20 AM   #35
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Interesting discussion. I have six GPS receivers on my vessel. When at anchor they do little to tell me what direction is north. Picture leaving an anchorage in the fog and dark when pulling up anchor. The oil filled compass is an a$$ saver in this event.

I have two electronic compasses, one flux gate and the other rate compensated. You got it, they seldom agree on heading or cmg. Then trying to get AIS trying to agree with AARPA. Hah, too much data. 😟
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Old 09-17-2016, 06:41 AM   #36
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While I agree with Bakers comment too....

How many here understand the difference between ssatellite compasses and electronic compasses (flux and rate)?

And while single gps units look like they are providing heading or bearing lines...is is really just a representation of direction of travel, not the head of the boat.

As to true or magnetic, depends on what you have selected.

I havent stayedcreal caught up on the advancements in GPS positioning for the last few years but.... boats at rest without a satellite compass will give jumping COGs, with or without much dampening. Not sure how dampening filters have evolved, but any random displacement from position errors will cause the jump, filters at best might just slow it down.
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Old 09-17-2016, 07:08 AM   #37
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GPS heading sensors use either two or three GPS receivers and do give heading. They are shaped like a big banana or a large triangular antenna. They do give heading whether moving or not. The problem with them is: They need completely unobstructed sight at all times and the resulting location is almost invariably very high. Which makes them liable to the oscillation which makes the heading jump. But if you dampen it down it is unresponsive when maneuvering.
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Old 09-17-2016, 07:28 AM   #38
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Quote:
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.
So your actual heading in that case is coming from the magnetic field driven rate compass, NOT GPS!



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GPS heading sensors use either two or three GPS receivers and do give heading. They are shaped like a big banana or a large triangular antenna. They do give heading whether moving or not. The problem with them is: They need completely unobstructed sight at all times and the resulting location is almost invariably very high. Which makes them liable to the oscillation which makes the heading jump. But if you dampen it down it is unresponsive when maneuvering.
Now you are talking about $atellite compa$$/heading $ensor$, not the GPS plotter virtually all cruising boats have. Important to make the distinction to newbies.
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Old 09-17-2016, 07:36 AM   #39
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Yes, tons of confusion here, partly because of terminology, and partly due to misunderstanding of various pieces of equipment. Here's some of the confusion I'm reading:

- Some people are using the term "GPS" or "GPS map" to refer to a chart plotter. We can thank the automotive GPSs for this since on cars the GPS and charting (mapping) are a single unit and have come to be called a GPS. And to fuel the fire, many marine chart plotters now include an integrated GPS sensor too.

- We would talk across each other much less is we referred to our chart plotter and our GPS as separate devices/functions.

- A GPS gives position, of course, but it also give course over ground (COG) and speed over ground (SOG).

- COG and heading (HDG) are different. They differ by the effects of current, wind, etc.

- It hasn't come up yet, but SOG is different than STW (speed through water) for the same reason that COG and HDG are different.

- It's a little unclear what an "electronic" compass is. It probably means a fluxgate or rate compass.

- A rate compass and a flux gate compass are magnetic heading devices, though solid state. They report magnetic heading (HDG), and sometimes rate of turn (ROT). Some even report pitch and roll.

- A Sat compass is both a GPS and a heading sensor. It reports all the usual GPS data (COG, SOG, position), plus it reports all the usual heading sensor data like HDG, ROT, and pitch/roll.

- A Sat Compass includes 2 or more GPS receivers, and uses them to compute the heading. It is very accurate - more accurate than the best rate compass. All the sat compasses I'm familiar with also include a rate compass that is used to stabilize the GPS derived heading, and provide very rapid and accurate changes to heading. It also preserves heading through GPS outages like when passing under a bridge.

- A Sat Compass can report true heading where a fluxgate or rate compass can only report magnetic heading. In many, if not most cases, this doesn't matter. Other devices will often know and share the local variation so true heading can be computed and displayed if desired. But this matters when you get into commercial equipment, several of which require true heading (HDT) directly from the heading device. Class A AIS is an example, along with any IMO certified radar. These devices require a Sat Compass or a Gyro.

- A GPS can not report meaningful COG when there is no movement, or little movement.

- A heading sensor can report HDG regardless of boat movement.

- Every chart plotter that I have seen can display both COG and HDG. They can display it numerically in a data box, and graphically as part of the boat icon. Some display two different colored vectors emerging from the bow of the icon, one showing COG and the other showing HDG. Others show COG with a vector, and skew the boat icon itself to represent the heading. When you are in a strong cross current these can be significantly different. I have seen a difference of 15-20 degrees on a number of occasions.

- Auto pilots work much better with a heading sensor vs GPS COG. In fact, I think they all REQUIRE a heading sensor and will not work on COG.

- Radar overlay on a chart plotter often requires HDG. So consumer plotters will use COG, but HDG works much better, and some plotters will only provide overlay if HDG is available.

- ARPA/MARPA on a radar also requires HDG.

- You do not NEED a heading sensor to navigate. GPS will work fine. But lots of things will work much better if you have a heading sensor, and some things will only work if you have a heading sensor.

Sorry for being pedantic here. I know lots of people understand all this, but there is also clearly some misunderstanding about what the various devices do and what they enable.
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Old 09-17-2016, 07:40 AM   #40
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I use a quality hand bearing compass that is easy to create a dev card for .

It is used to then use the big compass as a steering unit.

Works as well with the Auto pilot with electric compass.
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