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Boundary Waters Quetico Forum :: Gear Forum :: My 2 compass disagree
 
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jwartman59
01/11/2018 07:21PM
  
7 degrees could mean 640 feet off bearing over a mile. That’s not good enough. If you live in the Midwest most everything is laid out in a big n/s e/w grid. The north south lines take into account the curvature of the earth. East west would be best. I worked for a government surveying, mapping department, we used hand grenades for a unit of measure.
 
mschi772
01/12/2018 06:22PM
  
mjmkjun: "How about returning both and purchasing just one reliable compass. (raving reviews are helpful here)"


Thing is: The Suunto MC2 is considered to be a good compass.
 
RLJ
01/12/2018 12:49PM
  
I would take both back and get two that read the same.
 
RLJ
01/12/2018 12:49PM
  
I would take both back and get two that read the same.
 
Wick
01/12/2018 01:57PM
  
I called suunto. They referred me to Forestry Supplies 800-647-5368 in Mississippi, who does all the compass warranty work. Forestry customer service told me to send them in and they would replace both instruments.


i took them to work with me to play more and ship them out.My partner messed with them and came to the same conclusion, they differ by 7-8 degrees. He is younger and has better eyes!


We went upon the roof to look at maint that needed done. I took the compasses with me to do some sighting of far away objects to see what the distance would look like between the two at the 7-8 degree off, pointing to the same degree. As i got to the top, i pulled theout of my pocket, threw one to him to play with,,completely missed him,,,and watched the compass bounce off the man ladder 2 or 3 times on the way down, bounce off the elect service, then hit the asphalt. About 30-35 ft. My partner laughed and said, i hope that was the bad one!


I went down and picked it up. Not even a scratch on it.


Now the best or worse part, i can’t decide,,,,,,,they read exactly the same now. I do not understand this at all,,,,
 
Wick
01/13/2018 04:52AM
  
So how much should i charge for fixing compasses for you guys? Really, i guess i could do it for free, but i am semi scared of heights,,and it isn’t a great time for me when i have to go up on the roof.
 
Savage Voyageur
01/12/2018 05:00PM
  
Now this is a real mystery. I have no real idea, just a guess.


Could it be that the one you dropped off the roof was the faulty reading one? Could it be that the compass needle that moves was not in the correct spot on the stationary pin to begin with?
Could it be that the drop somehow knocked the needle into the correct place?

 
boonie
01/12/2018 05:52PM
  
Now that they read the same, the only question is . . . do they read right?
 
butthead
01/13/2018 08:27AM
  
Wick: "So how much should i charge for fixing compasses for you guys? Really, i guess i could do it for free, but i am semi scared of heights,,and it isn’t a great time for me when i have to go up on the roof. "


May I interest you in a piece of company startup equipment for your new vocation, compass adjusting tool


May save time in production and improve safety!


butthead

PS: Ooopps, need to edit, misspelled piece, of course it's immortalized in Wick's response. bh



 
Wick
01/10/2018 07:47PM
  
I bought 2 brand new compasses, one for each canoe. They are both suunto mc-2 NH USGS. They disagree by about 7 degrees!

How would i tell which one is wrong?
 
Northwoodsman
01/10/2018 08:02PM
  
Check the declination adjustment, are they both set the same?. It sounds like they may be opposite. Are they both designated for the northern hemisphere? Make sure they both say NH on them.
 
andym
01/10/2018 08:19PM
  
Also, are you testing them by putting them next to each other? Or separately, by taking the orientation of the same point on a table? The latter is a better idea as they can affect each other.


Also, be careful that you aren't moving some piece of metal near them such as a belt buckle.
 
Wick
01/13/2018 04:56AM
  
Savage Voyageur:
Could it be that the drop somehow knocked the needle into the correct place?
"


This is what both of us thought. My partner hd mentioned before that he thought one compass needle did not move as freely and quickly as the other. When i went down to get it, i expected the needle to be diconnected, laying off to the side with liquid gone,,,ect. We looked at it under magnifying glass, did not see a piece of dirt dislodged or anything like that.
 
mjmkjun
01/13/2018 05:27AM
  
Wick: "So how much should i charge for fixing compasses for you guys? Really, i guess i could do it for free, but i am semi scared of heights,,and it isn’t a great time for me when i have to go up on the roof. "
Bwaaa hahaha You have a Wicked sense of humor, dude.

 
billconner
01/13/2018 12:55PM
  
Sounds like tates compasses.
 
Wick
01/13/2018 10:41AM
  
butthead: "Wick: "So how much should i charge for fixing compasses for you guys? Really, i guess i could do it for free, but i am semi scared of heights,,and it isn’t a great time for me when i have to go up on the roof. "



May I interest you in a piecs of company startup equipment for your new vocation, compass adjusting tool



May save time in production and improve safety!



butthead



"
That would keep me from climbng,,but would raise prices,,high tech and all that.
 
andym
01/13/2018 11:49PM
  
If the needle wasn’t resting on the bearing correctly the extra friction could cause it to stop rotating before getting to magnetic NS. I’m surprised, though, that it was so consistent as you moved it around.
 
drnatus
01/14/2018 08:21AM
  
billconner: "Sounds like tates compasses."



I get that reference!

 
WIMike
01/14/2018 09:17AM
  
andym: "Good idea about the local airport. That's great if they have an accurate compass rose. How accurate are the runway orientations? Don't they often give them just to the 10 degrees?"


Airport runways are labeled in 10 degree increments. ex. Rwy 27 could have a heading of anywhere from 265-275, can’t remember whether the 5s go to next higher or next lower. The exact runway heading is displayed on airport diagrams accessible by the public though. Ask at the airport and they can tell you an exact runway heading.
 
24kGold
01/14/2018 05:49PM
  
My two daughters were made by the same manufacturer. They both disagree by 180 degrees. Go figure.
 
Wick
01/10/2018 08:15PM
  
The declination on both is still at zero. They are both NH. Exact same model of compass. I bought 2 of the same so it would not matter which canoe had which compass, and only one type compass to learn.
 
old_salt
01/10/2018 09:10PM
  
Return the defective one.
 
gymcoachdon
01/11/2018 01:06AM
  
butthead: "I don't think any side by side simultaneous comparison is accurate. Too much variable interference. If I put all my compasses on a table they all read different.



Take one out and check the bearing to a distant object. Then check the other independently, same compass position same distant object. Even then if they disagree it's consistency for the individual compass that is important. As long a each constantly indicates the same repeatably, you can adjust for that. Unless you expect to do some technical orienteering or triangulating compass exercises, navigation is sort of like horseshoes, close is often good enough.



butthead"


That is a great answer.
I always listen to butthead...
 
Wick
01/10/2018 08:37PM
  
andym: "Also, are you testing them by putting them next to each other? Or separately, by taking the orientation of the same point on a table? The latter is a better idea as they can affect each other.



Also, be careful that you aren't moving some piece of metal near them such as a belt buckle."


I have tested them everywhere. I put them on coffe table with a brand new phone book between them so the edges are parallel, and they are approx 11 inches apart. The bezels are lined up with north and south. No matter how i position everything, they read from 7-10 degrees different.
 
Savage Voyageur
01/11/2018 09:09AM
  
I have a similar compass only with the global needle, not the North America needle. If you decide to take one back look into the global needle model. I have no idea why it would be off 10 deg, because the only thing that is steel in the compass is the needle. Maybe the compass needle somehow got slightly magnetized. I wonder if it was stored near a electrical device of a large magnet like a speaker to throw it off. To determine which one is wrong you need to get a third compass to weed out the bad one.
 
Ausable
01/11/2018 09:34AM
  
Both of the compasses could be off and in opposite directions. If you have a map of your local area that you could use and you know what the local declination is, you could determine how much and in which direction each compass varies from perfection. For instance, you could stand at a particular spot and orient each compass to an object that is at a known angle from your position.
 
ParkerMag
01/11/2018 10:11AM
  
A man with one watch knows what time it is. A man with two...


Seems odd to me, but I'm not a compass nut. I subscribe to the "close enough" school of thought too.
 
thebotanyguy
01/11/2018 10:42AM
  
The Suunto compasses you have are not inexpensive units, and for the price I would demand that each is operating properly. Return the defective compass.


Now, how does one determine which one is inaccurate? Perhaps you have a straight stretch of road nearby that runs north/south. Take a bearing down the road to determine accuracy of your compasses, taking the declination into consideration of course.
 
andym
01/11/2018 11:06AM
  
As a last inside check, when you do the phone book thing, and then swap which compass is where, does the bias between the two compasses remain the same? The magnetic field can change rapidly inside a house with pipes and wiring. I know this from trying to orient an inlaid compass rose in our floors.


If it is clear that one is bad, I agree with going outside and using a long straight road to see which one is off. Or call a geologist at a local university and ask if you can test against their compass. They probably have a brunton pocket transit which is very high quality. Or call a surveyor.


Yes, 7 degrees isn’t a big problem for navigating but I would still return the bad one. But then, I use my compass for work and 7 degrees off on lots of observations just isn’t worth dealing with.
 
butthead
01/10/2018 09:24PM
  
I don't think any side by side simultaneous comparison is accurate. Too much variable interference. If I put all my compasses on a table they all read different.


Take one out and check the bearing to a distant object. Then check the other independently, same compass position same distant object. Even then if they disagree it's consistency for the individual compass that is important. As long a each constantly indicates the same repeatably, you can adjust for that. Unless you expect to do some technical orienteering or triangulating compass exercises, navigation is sort of like horseshoes, close is often good enough.


butthead
 
drnatus
01/11/2018 07:06AM
  
butthead: "I don't think any side by side simultaneous comparison is accurate. Too much variable interference. If I put all my compasses on a table they all read different.



Take one out and check the bearing to a distant object. Then check the other independently, same compass position same distant object. Even then if they disagree it's consistency for the individual compass that is important. As long a each constantly indicates the same repeatably, you can adjust for that. Unless you expect to do some technical orienteering or triangulating compass exercises, navigation is sort of like horseshoes, close is often good enough.



butthead"


don't disagree with any of the above, but there is something disconcerting about this.
 
Northwoodsman
01/11/2018 07:52AM
  
Can you post a picture of both of them side by side a few inches apart (but parallel) to show us.
 
Blatz
01/11/2018 08:36AM
  
Just send 1 back and say "hey follow me" Problem solved
 
Wick
01/11/2018 11:54AM
  
i can put up with a degree or maybe two,,,but 7-10 is too much. I believe I can point my finger more accurately then that! LOL,,,maybe.


I will try the airport.


Andym, yes, i switched positions every place i tried them and the results followed the compass. I had the kitchen table baffling me for a while until i saw it had a metal expansion rail under it to add leaves to the table. I can get completely away from metal, outside, and the error does not change.


i just bought a new gps too. I will see if i can find a way to check with that tonite. These things are too expensive to be that far off!
 
Huntindave
01/11/2018 06:39PM
  
Wick: "I bought 2 brand new compass, one for each canoe. They are both suunto mc-2 NH USGS. They disagree by about 7 degrees!


How would i tell which one is wrong?"


They may both be off BUT you can correct that so they will both be dead on.


The quality control for this compass is 2.5 degrees. The two could be 5 degrees different and still be within the quality control specs for the product.


You can adjust these so they are both dead on. Any compass that is adjustable for declination can be made to read dead on.


for example; if your compass is pointing dead on the magnetic north and the area your in has 12 degrees declination error, one would adjust the compass by 12 degrees.


However if your compass is pointing 3 degrees off from magnetic north then just adjust for declination by either 9 degrees or 15 degrees (dependent on the direction the 3 degree error is)
After this correction is done for both compasses, you can use them without regard to which one you have in you hand at the time.

Below is a review taken from the Suunto web site;

Good, except for declination accuracy.
As a volunteer with The Mountaineers, and Seattle Mountain Rescue, we see this compass being used all the time. Some percentage of them have the declination scale offset about 2 degrees from the degrees scale on the bezel. For example, we set it to 16 East for Seattle, but find that we are always 2 degrees low at a calibrated compass check station that we use. We change them to 18 degrees East and the compass then measures the bearing accurately."
 
mjmkjun
01/12/2018 11:46AM
  
How about returning both and purchasing just one reliable compass. (raving reviews are helpful here)
 
andym
01/12/2018 04:27PM
  
Impact can remagnetize a needle. However, the odds that a drop like that had the right impact at the right moment when the needle is NS, seems unlikely.
 
boonie
01/11/2018 11:20AM
  
To be honest, I rarely use a compass in the BW except in the general sense of I'm Going/looking SW not SE or a general bearing. It's pretty easy in most places to just orient the map to the landscape and follow it like orienteers do - keeping track of islands, bays, points, campsites, portages . . .


I'd still want my compass to be more accurate than 10 degrees though. Besides the methods already offered, if you can find the Pole Star, you could take readings on it.
 
butthead
01/11/2018 11:26AM
  
Another way to check each is a quick trip to a local small airport. Most have a compass rose set in a foundation and offer current on the spot declination correction. You could then shoot a reading down a taxiway or even a runway.


butthead
 
andym
01/11/2018 03:57PM
  
Good idea about the local airport. That's great if they have an accurate compass rose. How accurate are the runway orientations? Don't they often give them just to the 10 degrees?
 
cowdoc
01/11/2018 04:14PM
  
Wick: "i can put up with a degree or maybe two,,,but 7-10 is too much. I believe I can point my finger more accurately then that! LOL,,,maybe.



I will try the airport.



Andym, yes, i switched positions every place i tried them and the results followed the compass. I had the kitchen table baffling me for a while until i saw it had a metal expansion rail under it to add leaves to the table. I can get completely away from metal, outside, and the error does not change.



i just bought a new gps too. I will see if i can find a way to check with that tonite. These things are too expensive to be that far off!"


Lucky you didnt buy 2 new GPS units......