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#199013 - 03/26/10 07:52 PM Re: Recommendation for a decent compass [Re: BorkBorkBork]
KenK Offline
"Be Prepared"
Pooh-Bah

Registered: 06/26/04
Posts: 2210
Loc: NE Wisconsin
All of the compasses mentioned above are good compasses. Suunto M-3, Suunto MC-2, Brunton 15TDCL (my own favorite), Brunton 8099, Brunton. I have all but the MC-2. You can't go wrong with any of them.

I bought a Cammenga and found it to be pretty cool and really tough, but I still prefer the good plastic baseplate compasses.

One of the nice things about the Brunton Eclipse compasses is that the area where you read the bearing is magnified - which makes things much easier for those of us who have "old eyes".


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#199017 - 03/26/10 09:23 PM Re: Recommendation for a decent compass [Re: JBMat]
haertig Offline
Pooh-Bah

Registered: 03/13/05
Posts: 2322
Loc: Colorado
Originally Posted By: JBMat
You can find your magnetic declination at magnetic-declination.com

Or your can find it printed on any topo map. If you aren't using a map, then you don't need to worry about declination anyway.

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#199019 - 03/26/10 10:49 PM Re: Recommendation for a decent compass [Re: haertig]
scafool Offline
Pooh-Bah

Registered: 12/18/08
Posts: 1534
Loc: Muskoka
One advantage of using the online declination calculator is that you avoid the correction calculation for what year the map was made.
The problem is not so much that you might make a math mistake as it is the world isn't so easily predictable.
They marked the declination in the year the map was made and then marked an estimate of how much it was changing each year.
The estimated rates of change are not always accurate. The calculator uses newer measurements of the yearly change as the magnetic pole wanders about.

I suggest taking any maps you might be using and get the correct current declination for them. Then you can mark a short straight line on your map at the corrected magnetic bearing and mark it.
I draw this line in red with the magnetic declination and year beside it.


Edited by scafool (03/26/10 10:50 PM)
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#199021 - 03/26/10 11:36 PM Re: Recommendation for a decent compass [Re: scafool]
hikermor Offline
Geezer in Chief
Geezer

Registered: 08/26/06
Posts: 7705
Loc: southern Cal
While I would certainly use as current a declination figure as is conveniently available, most of the time the yearly changes, even over a decade or so won't make a significant difference in the real world. Local variation, whether the iron ore underfoot or the metal screws in your eyeglasses, is likely to be far more significant.

I always carry a compass, but rarely need to use it in terrestrial situations. At sea is a different story.
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#199023 - 03/27/10 12:04 AM Re: Recommendation for a decent compass [Re: Teslinhiker]
Art_in_FL Offline
Pooh-Bah

Registered: 09/01/07
Posts: 2432
Originally Posted By: Teslinhiker

Not so sure about making a blanket statement on this. I have a cheap Silva ($14.00 originally) that I would not classify as reliable. A compass being out a few degrees over a fair distance can make a difference in finding your destination whether it be your camp or your vehicle. Sure you end up in the general area you need to be but when light is fading fast or bad weather is hitting you, I prefer to have a compass that gets me closer to where I was originally headed for.


From an engineering standpoint it is pretty hard to make a pointer that won't point accurately. The main weakness is typically not pointing but the bearing binding. Silva has a very well designed bearing and assuming it was assembled correctly at the factory there is little that can go wrong.

Perhaps you got a bad one. Rare, I've never seen one new that was defective, but I suppose it is possible. Or perhaps the compass is a knockoff with a cheap bearing. There are look-alike compasses that are inconsistent. I recently laid out a half dozen of these in a local Wally and there was a few degrees difference that came and went if I shook them. Almost certainly a bearing issue.

I have used a very basic Silva for many years and it points as accurately as the USGI lensatic and surveyor's compasses I have checked it against. More expensive compasses get you a larger dial, fancier case, and features like adjustable declination.

Adjustable declination can be a mixed blessing. I had someone insist that my cheap compass was off because his much more expensive model was pointing differently. We checked it against a known N-S road and his was off by better than ten degrees. Come to find out he set the declination for his trip in the SW and hadn't reset it for the SE. Adjustable declination means you can make it inaccurate. Mine consistently follows the magnetic lines. For true north I need to remember to correct for this and when orienteering, where a variation of five meters over several kilometers can alter your score, I slap on a piece of tape with the declination written on it to remind me and use a pace counter.

Most of my camping and hiking is in Florida and there isn't enough declination or any scoring demanding fine accuracy. I mostly go by landmarks and only need a compass to get my rough orientation.

Discounting issues with ferrous metals causing deviation, a pretty common issue, IMHO the main source of inaccuracy is reading errors. Possibly the biggest detriment to any base-plate model is that they require you to hold it square to you, preferably with both hands, to get an accurate reading. I've seen people who couldn't read my compass accurately because they hold it off to one side or cock it slightly. With a little training they usually got it right.

But there is also parallax error and inability of most people to consistently read and practically use any angle smaller than about three degrees. And variations in eyesight and glasses don't help.

Most compasses intended for hand-held use are graduated in five degree increments. That is about as fine as most people can practically use. USGI lensatic and surveyor's compasses have finer graduations but unless you mount them on a tripod the finer graduations are largely superfluous.




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#199027 - 03/27/10 12:17 AM Re: Recommendation for a decent compass [Re: haertig]
Yuccahead Offline
Member

Registered: 07/24/08
Posts: 199
Loc: W. Texas
Originally Posted By: haertig

I've always wanted to try one of those Cammenga lensatics that the military uses. I want to "try before you buy" to see how they work for my nearsighted/bifocal eyes. Maybe I'll ask my daughter if she can borrow one from her ROTC the next time she comes home from college.


Haertig,
If your daughter cannot provide, County Comm sells a 'training version' of the GI lensatic compass for $11.50 plus the gig for shipping. Standard disclaimer and I have no experience with this particular model.
http://www.countycomm.com/trainingcompass.htm
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#199028 - 03/27/10 12:21 AM Re: Recommendation for a decent compass [Re: Yuccahead]
thseng Offline
Old Hand

Registered: 03/24/06
Posts: 900
Loc: NW NJ
Originally Posted By: Yuccahead
If your daughter cannot provide, County Comm sells a 'training version' of the GI lensatic compass for $11.50 plus the gig for shipping. Standard disclaimer and I have no experience with this particular model.
http://www.countycomm.com/trainingcompass.htm

The difference with that one is that it is liquid damped rather than induction damped like the real one. Should be fine to test the lens arrangement, though.
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- Tom S.

"Never trust and engineer who doesn't carry a pocketknife."

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#199029 - 03/27/10 12:38 AM Re: Recommendation for a decent compass [Re: thseng]
jzmtl Offline
Addict

Registered: 03/18/10
Posts: 530
Loc: Montreal Canada
Originally Posted By: thseng
Originally Posted By: Yuccahead
If your daughter cannot provide, County Comm sells a 'training version' of the GI lensatic compass for $11.50 plus the gig for shipping. Standard disclaimer and I have no experience with this particular model.
http://www.countycomm.com/trainingcompass.htm

The difference with that one is that it is liquid damped rather than induction damped like the real one. Should be fine to test the lens arrangement, though.


That's just a Brunton 9077 without marking, no need to go through county comm to get one.

Edit actually it's not, but but close enough you can get a brunton from local store to play with.


Edited by jzmtl (03/27/10 01:26 AM)

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#199032 - 03/27/10 01:44 AM Re: Recommendation for a decent compass [Re: ILBob]
Teslinhiker Offline
Veteran

Registered: 12/14/09
Posts: 1419
Loc: Nothern Ontario
Originally Posted By: ILBob

How does any compass manage to be "off" by a few degrees. It points to the north pole (or rather along the lines of magnetic force). That is the same for all compasses.

Granted some are easier to take precise measurements with. Perhaps that's what you meant. But that is often related to operator proficiency.


Not all compasses are created equal in terms of materials and workmanship. Yes compasses should point to north, however how accurate that compass is in degrees was my point. If you are looking for a way to give you an overall indication and direction of travel to follow then yes, almost any compass can provide that.

My background includes 3/12 years of competition orienteering where dead point accuracy is tantamount. After trying almost every compass on the market at the time (and even currently), perhaps I am just too picky on my never ending quest for compass accuracy...
_________________________
Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.

John Lubbock

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#199035 - 03/27/10 01:56 AM Re: Recommendation for a decent compass [Re: jzmtl]
Byrd_Huntr Offline
Old Hand

Registered: 01/28/10
Posts: 1174
Loc: MN, Land O' Lakes & Rivers ...
I use two different compasses. The Brunton Baseplate 7DNL is great for use with a map, and it has adjustable declination. or rather a declination scale. I don't really use that feature where I live because declination is almost zero. For walkabouts, hunting, and canoeing, I use my old fashioned brass Taylor compass. I figure if it was good enough for the US Corps of Engineers, it's good enough for me. You can still get these for the price of a high-end modern compass.


Attachments
BRUNTON 7DNL BASEPLATE MAP COMPASS.jpg

Taylor US Corps of Engineers WWI brass compass 33.jpg


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