I was going to install a new chart plotter, but according to the instructions it has to be at least 32" from the compass. However, the store manager at West Marine said that most people ignore this and it doesn't cause any problems. What do you think? Is this true?
distance from compass
- Thread starter John R
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The compass will be off if placed near radios, speakers or just about anything powered. The readings can still be steady but will not be correct.
Garmin placed magnets, of all things !!!, inside the doors of their newer chartplotters a few years ago. One of those "What were they thinking?" moments. Most folks have either removed the magnet (although Garmin didn't like that) or lived with the deviation of their magnetic compasses. If you can, power it up before you install it with some temporary power wiring, and see what happens.
FYI, this issue had been beaten to death over two years ago. You may find some stuff if you do a search on "Garmin magnets".
Indeed, I just did and there's lots to read.
Good luck.
FYI, this issue had been beaten to death over two years ago. You may find some stuff if you do a search on "Garmin magnets".
Indeed, I just did and there's lots to read.
Good luck.
We recently mounted a 5" chartplotter about 10" above our compass. Before I installed it i held the unit in different places all around the compass and didn't see any deviation. Having said that, this was in no way a scientific study, and I don't know that I would trust it for sailing any distance where a few degrees of deviation would matter.
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I have a 5" Garmin
Mounted just about 6 inches in front of the compass. It is one that does not have the magnets in the door, and I can tell no difference, with the unit mounted, unmounted, powered up or not. The only way to tell for sure is to give it a try. Try it both with power on and power off, at various distances.
Mounted just about 6 inches in front of the compass. It is one that does not have the magnets in the door, and I can tell no difference, with the unit mounted, unmounted, powered up or not. The only way to tell for sure is to give it a try. Try it both with power on and power off, at various distances.
Here are a couple of pictures of what it does to my compass. I think that the compass quality and strength of the compass magnets would determine how much it actually affects your readings. Here it is about 2-3 degrees on this "heading".
Magnet door Garmin in place on the first picture, absent on the second. Magnet is on the outboard side of the bottom corner of the Garmin; about 12 inches away from the compass. Mounted left side of pedestal or on top would produce much bigger problems with the compass.
Magnet door Garmin in place on the first picture, absent on the second. Magnet is on the outboard side of the bottom corner of the Garmin; about 12 inches away from the compass. Mounted left side of pedestal or on top would produce much bigger problems with the compass.
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On my boat,the chart plotter is mounted directly above the compass on the pedestal, that was the way Beneteau designed the instrument pod. I really never swung the compass and have always noted about a 10 degree variance between the magnetic compass and the chartplotter or the autopilot compass which reads its compass mounted below. I only recently found out where the mounting screws for the compass were hidden. now I can at least get at the compensation screws. All I need USA flat calm day to get out on the lake to do the adjustment routine.
It's is obviously really way off when I am tied up next to a steel seawall.
It's is obviously really way off when I am tied up next to a steel seawall.
One thing that new boat buyers often overlook in the initial romance of possessing their New Boat is that the builder willingly makes compromises in fitting it out. The Primary purpose of deck and electronics gear, as installed, is to help visually sell the boat at a static display dockside or inside a large heated building in January.
Equally, one could argue that the install instructions buried deep in the instrument install manual are biased due to their lawyer's liability concerns...
Still, when Garmin or Simrad or Raymarine tells you that the MINIMUM Safe Distance is 17 to 37 inches, there is no fricken safe way you can install it on the guard above the ship's compass.
I just went through this when sourcing a new plotter/radar combo. Ended up with a Lowrance, that uses a friction catch for its chip door. No matter where we held it, in any position, the compass did not respond. Not so with several brands I borrowed from the store to try - within a couple feet of approach the card began to swing 5 or 10 degrees.
I have done a lot of overnight passages in the last 30 years, and while I love GPS, there have been many trips where double checking headings with the compass was absolutely vital. It's your only instrument that works when the electricity does not...
Ask that manager to put that professional opinion in writing, so that your grieving family will have it on file to present to their attorney.
I asked a WM employee about that same issue, and he said he had never heard of it. Didn't seem particularly concerned, either.
Ask your questions at a real marine electronics store. Where we live they will usually match or beat the WM price and actually know that they are talking about.
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My helm-mounted GPS, a Garmin 76csx, affects the compass. It's very slight, so am not all that concerned regarding local navigation if the GPS fails.
However, it does affect it. This means uncorrected error. If I were to lose the GPS (and backup) offshore or in unfamiliar waters, I would merely detach the GPS and store it, freeing the compass.
However, it does affect it. This means uncorrected error. If I were to lose the GPS (and backup) offshore or in unfamiliar waters, I would merely detach the GPS and store it, freeing the compass.
I'm not the OP, but since you asked...
New dome, pivots, and fresh fluid. Now it responds quickly, settles nicely, and is amazingly easy to read. Best of all, all the rebuild and the swinging (out on the water) cost me less than a third of the price of the same compass model brand new.
He even mirror polished the ss base and put a new label on it. Replaced both the old light buibs (one was burnt out) with new red LED's.
Better yet, now, our deviation card reads -- all the way down the list of directions -- "Steer to Compass" !
:dance:
Yippee!
Not sure to whom this is directed, but... ours was always ok within a "few degrees" as verified by charting for a given course. Last year I finally had a compass adjuster rebuild it completely.
New dome, pivots, and fresh fluid. Now it responds quickly, settles nicely, and is amazingly easy to read. Best of all, all the rebuild and the swinging (out on the water) cost me less than a third of the price of the same compass model brand new.
He even mirror polished the ss base and put a new label on it. Replaced both the old light buibs (one was burnt out) with new red LED's.
Better yet, now, our deviation card reads -- all the way down the list of directions -- "Steer to Compass" !
:dance:
Yippee!
How accurate a course can you steer to a compass? I would guess I am only good for +-10 degrees what with waves, gusts, paying attention to other stuff etc.
There be good helmsmen and there be bad ones. In flat seas and fog and motoring I have dead reckoned about 5 NM to within 15 ft of a floating nav beacon. after doing the trig that comes out to 1.7 minutes of arc (toot, toot)(I try to stay humble but it is proving to be a challenge)
In "normal" conditions most of my Corinthian crew can steer to 3 degrees (1.5 +-). Some be bad though, and can't seem to get closer than about 45 degrees.
In "normal" conditions most of my Corinthian crew can steer to 3 degrees (1.5 +-). Some be bad though, and can't seem to get closer than about 45 degrees.
Asking West Moron about electronics advice is akin to asking a Walmart employee on their opinions on the sander that they just put on sale..
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