Recommendation for a decent compass

Posted by: Outdoor_Quest

Recommendation for a decent compass - 03/26/10 01:16 AM

What would be your selection for a good compass for land navigation?

I like the Brunton 8010G and a Sunto (can't think of the model number) to go with me in the woods.

I like a compass that you can adjust for declination.

Blake

www.outdoorquest.biz
Posted by: Teslinhiker

Re: Recommendation for a decent compass - 03/26/10 01:35 AM

I use the Sunnto M-3D compass. Great compass for the price ($28.00 to 35.00 depending on where you shop.) The compass is very accurate for my needs which range from dense forest to open grasslands to alpine meadows. It also adjusts easily for declination.



MEC in Canada also sells the same M-3D compass for $28.00




Posted by: dougwalkabout

Re: Recommendation for a decent compass - 03/26/10 01:57 AM

Just so I understand ... in the old Silva Rangers, there was a screw so you could adjust the 360 bezel for local declination. Is that the same with the newer compasses? Thx.
Posted by: Art_in_FL

Re: Recommendation for a decent compass - 03/26/10 02:02 AM

Any in the Sunnto or Silva line will do. You can spend as much as you like but a $10 compass from a reputable company will get you there as reliably as a $120 one will. More money buys you more features, and some of those can be handy, but, in the end, a compass just tells you which way is north.
Posted by: Teslinhiker

Re: Recommendation for a decent compass - 03/26/10 02:05 AM

Originally Posted By: dougwalkabout
Just so I understand ... in the old Silva Rangers, there was a screw so you could adjust the 360 bezel for local declination. Is that the same with the newer compasses? Thx.


Doug, That is the case with the Sunnto M-3D. There is a small set screw on the bottom side of the compass at roughly the 40 degree mark. The small silver tool shown on the end of the lanyard is for this set screw.
Posted by: Teslinhiker

Re: Recommendation for a decent compass - 03/26/10 02:13 AM

Originally Posted By: Art_in_FL
Any in the Sunnto or Silva line will do. You can spend as much as you like but a $10 compass from a reputable company will get you there as reliably as a $120 one will. More money buys you more features, and some of those can be handy, but, in the end, a compass just tells you which way is north.


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.
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/26/10 02:31 AM

Does anyone have any experience with the Brunton 8099? Local store has it for a good price but reviews are mixed.



Actually nevermind, I remembered I can't use any of the sighting compasses because I have one of those easyclip eyeglass frames.. smile
Posted by: scafool

Re: Recommendation for a decent compass - 03/26/10 03:06 AM

The Eclipse?
I used one on a bit. Nothing wrong with them.
I thought it was a bit fiddly at first with the circles to line up but I got used to it OK.

I think the Brunton 8099 is fine if the price is good. I still use my older Silva and Sunnto compasses that have been fine for me for years but that is mostly because I am much more used to them.
However if I was buying a new compass I would certainly consider another eclipse.
I use the sighting compasses like rangers and K series Sunnto so Eclipse serves just like the Ranger compass does.

I will tell you that even if you could sight a compass to seconds instead of degrees it would not help much.
The Earth's magnetic field has enough change in it that you wont ever get better than 1 degree accuracy anyhow.
If you can get within 2 degrees true consistently you are doing very good with a magnetic compass.

Edit. I was actually answering Jzmtl but the answer holds.

I do find I have uses for the sighting compasses so I like the Ranger types with the mirrors. I am not as fond of the military style engineer compasses because I find them awkward to focus on and read when sighting a line.
Posted by: Outdoor_Quest

Re: Recommendation for a decent compass - 03/26/10 03:29 AM

It sure is. That small screw adjusts your compass for declination.

Blake
Posted by: EMPnotImplyNuclear

Re: Recommendation for a decent compass - 03/26/10 08:24 AM

Anyone use Solar Powered Digital Compass Altimeter + Barometer + Thermometer?
Posted by: MostlyHarmless

Re: Recommendation for a decent compass - 03/26/10 09:30 AM

Originally Posted By: EMPnotImplyNuclear
Anyone use Solar Powered Digital Compass Altimeter + Barometer + Thermometer?


AVOID, AVOID, AVOID, AVOID... sorry you just set of my AVOID alarm. It is very sensitive to such word compositions. I associate them with a much simpler word: Junk.
Posted by: Byrd_Huntr

Re: Recommendation for a decent compass - 03/26/10 10:40 AM

Originally Posted By: Outdoor_Quest
What would be your selection for a good compass for land navigation?

I like the Brunton 8010G and a Sunto (can't think of the model number) to go with me in the woods.

I like a compass that you can adjust for declination.

Blake

www.outdoorquest.biz


Magnetic declination is a really big deal in some parts of the country. What might be construed as inaccuracy in a compass might actually be due to the extreme angles of the magnetic lines in a given area, to minerals in the rocks and soils, or to whatever you have in your pockets. I stood one day on the highbanks of lower Lake Superior, in an area where many shipwrecks lie on the bottom, and wondered why experienced sea captains would founder on the rocks in a channel that was 17 miles wide. An old ranger told me that in the days before GPS when magnetic compasses were the primary navigation devices, there was so much iron in the rocks that they attracted the compass needle and at night the ships would hit the rocky shores under full power. They built many lighthouses around the lake for this reason.

I have a map showing the magnetic lines in the USA for 2004 (they change constantly as the iron core of the Earth shifts).
Posted by: sybert777

Re: Recommendation for a decent compass - 03/26/10 11:49 AM

Cool! Im right on the 0! I have a Silva I can Sell! Its made in Sweden, its A CL15 ranger!
Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/26/10 12:08 PM

I prefer the globally adjusted compasses since I travel a lot.
Below are the only brands I have found to have globally adjusted compasses for inclination and they are also adjustable for declination.

Silva, the Voyager Global series, 8010, 8020, 8040.
(Silva is called Brunton and Nexus in the USA).

Suunto (Suunto MC-2 Global, Suunto M3 Global) and the Recta company (Recta belongs to Suunto).

This is the one I use and I like it a lot.
Recta DT 420G
http://www.recta.ch/en/dt-420g

I am interested in finding other brands that have globally adjusted compasses (I collect compasses) which also includes an adjustment for declination, so if you have any tips, please tell me.
Posted by: Russ

Re: Recommendation for a decent compass - 03/26/10 01:16 PM

I went with the Suunto MC-2G
Quote:
This compass is our "BEST PICK" for overall features. You can use the clear baseplate with maps, sight with the mirror, and never slow your stride with the global needle that accepts tilts up to 20 degrees and still reads accurately. To top it all off, the global needle has a quicker dampening time than a standard needle. Other professional features that make this compass a BEST PICK are the built-in clinometer, adjustable declination, luminous bezel, luminous guidance points, and convenient map scales.. . .
Posted by: ILBob

Re: Recommendation for a decent compass - 03/26/10 01:59 PM

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.


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.
Posted by: haertig

Re: Recommendation for a decent compass - 03/26/10 02:36 PM

I have a Brunton 8099 Eclipse that I like very much. The best part of it for me is that you can sight your target and then remove the compass from your eye level and read the bearing separately. This is nice for severly nearsighted, bifocaled eyes like mine. At first the 8099 looks complex with all those folding thingys on it, but it's very easy to use. I recommend it. Mine does develope a small bubble in the fluid at high altitures(11k+) however. This doesn't appear to affect function, but it is annoying to look at.

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.
Posted by: NobodySpecial

Re: Recommendation for a decent compass - 03/26/10 03:48 PM

Originally Posted By: ILBob
[quote=Teslinhiker]How does any compass manage to be "off" by a few degrees.

It can't - assuming they managed to print the angles in the right order! As long as the needle is magnetized it will work, cheap button compasses have weak needles that are easily demagnetized.

You can have compasses that are faster to settle, clearer to read and work more reliably if they aren't held exactly flat.

If you live on the east or west coast get one with declination adjust or just draw a new north line with a sharpie. If you line down the middle, or in the UK just buy any baseplate compass.

One degree off means you are only going to be out about 25yards in a mile, and there aren't many places you are marching purely on a compass bearing further than that without any landmarks.



Posted by: JBMat

Re: Recommendation for a decent compass - 03/26/10 04:58 PM

You can find your magnetic declination at

magnetic-declination.com

Altitude can be found at geonames.org
Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/26/10 07:42 PM

Each degree off will result in an error that is 1/60:th of the distance travelled. If you travel one mile (1760 yards) with one degree declination and you do not compensate, you will be 29.33 yards off course.

With a 15 degree declination you will be 440 yards off course !!



Posted by: KenK

Re: Recommendation for a decent compass - 03/26/10 07:52 PM

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".

Posted by: haertig

Re: Recommendation for a decent compass - 03/26/10 09:23 PM

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.
Posted by: scafool

Re: Recommendation for a decent compass - 03/26/10 10:49 PM

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.
Posted by: hikermor

Re: Recommendation for a decent compass - 03/26/10 11:36 PM

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.
Posted by: Art_in_FL

Re: Recommendation for a decent compass - 03/27/10 12:04 AM

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.



Posted by: Yuccahead

Re: Recommendation for a decent compass - 03/27/10 12:17 AM

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
Posted by: thseng

Re: Recommendation for a decent compass - 03/27/10 12:21 AM

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.
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/27/10 12:38 AM

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.
Posted by: Teslinhiker

Re: Recommendation for a decent compass - 03/27/10 01:44 AM

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...
Posted by: Byrd_Huntr

Re: Recommendation for a decent compass - 03/27/10 01:56 AM

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.
Posted by: Teslinhiker

Re: Recommendation for a decent compass - 03/27/10 02:17 AM

Byrd_Huntr, let me know if you ever tire of owning the Taylor...

The Brunton 7DNL is a good little compass for the price and is the one I will be getting my nephew for his first compass.
Posted by: EMPnotImplyNuclear

Re: Recommendation for a decent compass - 03/27/10 04:08 AM

Originally Posted By: MostlyHarmless
Originally Posted By: EMPnotImplyNuclear
Anyone use Solar Powered Digital Compass Altimeter + Barometer + Thermometer?


AVOID, AVOID, AVOID, AVOID... sorry you just set of my AVOID alarm. It is very sensitive to such word compositions. I associate them with a much simpler word: Junk.

Yes, the marketing does set of junk alarms, but it can't be all that bad. I'm a little surprised no one has any experience at all to contribute.
Posted by: haertig

Re: Recommendation for a decent compass - 03/27/10 04:37 AM

Originally Posted By: jzmtl
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.

Thanks for the ideas. I never thought about buying a cheaper "trainer" just to test if the real deal might work with my eyes.

I also found where you can get a pair of these trainers for $13.47 (member price) at SportsmansGuide:

http://www.sportsmansguide.com/net/cb/cb.aspx?a=459641

I previously had written these off as junk imitations, but they might well be useful to test for eyesight issues and to play around with.
Posted by: MostlyHarmless

Re: Recommendation for a decent compass - 03/27/10 09:35 AM

Originally Posted By: EMPnotImplyNuclear
Originally Posted By: MostlyHarmless
Originally Posted By: EMPnotImplyNuclear
Anyone use Solar Powered Digital Compass Altimeter + Barometer + Thermometer?


AVOID, AVOID, AVOID, AVOID... sorry you just set of my AVOID alarm. It is very sensitive to such word compositions. I associate them with a much simpler word: Junk.

Yes, the marketing does set of junk alarms, but it can't be all that bad. I'm a little surprised no one has any experience at all to contribute.


I'm not.

This crowd is above average when it comes to optimizing the gear they use and bring with them, I am not at all surprised that no one here has tested this particular gadget. Too many gadgets, too little time... don't waste time on the gadgets that trip your junk-o-meter.

Quality scepticism aside, there are some objective reasons not to choose this particular combination of instruments. Here's why:

1) It violates the KISS principle. Big time. (Keep It Simple Stupid).

2) Base plate compasses (the transparent ones you can place on a map so it is easy to read direction from A to B) are pretty much what you want when using the compass with a map. I've yet to see a digital compass that you can use this way.

3) Neither altimeter, barometer nor thermometer are vital instruments for your survival. I can give you a long rant under which circumstances they are useful. My experience with altimeters is limited to the research I did before deciding NOT to buy one. I found out when and how it would be useful - and that was just too limited for my liking. In addition, altimeter use for navigation is made obsolete by the GPS. As a weather forecaster I have a pretty good idea of what you can extract from barometer and thermometer. Going into detail will be a long rant that concludes that you don't really need any of them. A compass, on the other hand, is vital.

4) Electronic gadgets can and will fail for a lot of reasons, including failure to charge the solar powered device during daylight hours. A good quality analog compass will only fail if you crush it or loose it.
Posted by: Byrd_Huntr

Re: Recommendation for a decent compass - 03/27/10 12:06 PM

Originally Posted By: Teslinhiker
Byrd_Huntr, let me know if you ever tire of owning the Taylor...



Although that's unlikely, it's good to see that you appreciate a nice piece of brass.
Posted by: RobertRogers

Re: Recommendation for a decent compass - 03/27/10 02:23 PM

I wouldn't choose a digital compass. You are relying upon electronics that can go bad in just the worst time.

KISS is indeed the way to go when choosing gear you rely upon
Posted by: joost

Re: Recommendation for a decent compass - 03/27/10 03:16 PM

Whatever you do, don't get a Silva voyager 8010.


Nice and high-vis, but the bezel creaks like the coffin-lid of a bad horror movie and the bevel markings are sort of stenciled and rub off very quickly (the black paint of the scale markings on the sides of the plate also seem to wear away quickl).

Half a year of daily carry and very frequent use and I can barely make out the bearing.

I also have a Recta DP 65, because I travel a lot.
Posted by: Brangdon

Re: Recommendation for a decent compass - 03/27/10 07:57 PM

Originally Posted By: EMPnotImplyNuclear
Anyone use Solar Powered Digital Compass Altimeter + Barometer + Thermometer?
I have all that in my watch. The compass is roughly equivalent to a button compass. It'll stop you walking round in circles, and make sure you are walking along a road in the right direction and not 180 degrees wrong. It's not really for precision orienteering. It's better than nothing, and it's main benefit for me is that I always have it on me, even if I wasn't planning to get lost.

I can't really comment on the barometer. All I've done with mine is compare it with a GPS height. In theory it might help you figure out which map contour line you are on, but only if you calibrate it first to a known reference, and even then the weather has to be relatively stable.

The purpose of the thermometer is to help the device correct the other sensors for temperature variations. It doesn't have much direct utility for the end-user.

Being solar powered is a big benefit for a gadget watch like this. It means you can use the features without worrying about bringing closer the time when you have to replace the battery; the features become free to use. MostlyHarmless mentioned a concern about it not being charged due to not enough sunlight or something. That's not been a concern for me. With normal wearing, my watch's power indicator has never dropped below "high". So this contributes to the "always with you, always available" vibe.

PS My watch is a Casio PRW-1500. Great if you like gadgets, but not the cheapest way to get a compass.
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/28/10 02:08 AM

Just ran into a store sale earlier today and picked up a Suunto MC-2G on impulse buy. Having buyer's remorse now, I really don't need a compass that good.
Posted by: NobodySpecial

Re: Recommendation for a decent compass - 03/28/10 02:23 AM

Originally Posted By: jzmtl
Suunto MC-2G on impulse buy. Having buyer's remorse now, I really don't need a compass that good.

Whats worse is they last a lifetime so you have a long time to remorse about it !
Posted by: hikermor

Re: Recommendation for a decent compass - 03/28/10 02:35 AM

Don't be too sure. It is light, reliable, and sturdy. When you rely on a compass, you often must trust it completely. Best to have very good gear. That mirror can come in handy for signaling, as well.
Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/28/10 08:09 AM

This is quite a sturdy and reliable compass, but a bit heavy and a bit expensive.

Francis Barker M-73 Mils version

Despite it being a bit heavy, I always bring it with me on my hikes.

Posted by: Russ

Re: Recommendation for a decent compass - 03/28/10 10:14 AM

What is it with the Army and mils (Milliradian)?? Why don't they use degrees like everyone else?
Posted by: JBMat

Re: Recommendation for a decent compass - 03/28/10 10:28 AM

The Army uses mils to be more precise. Precison is a good thing when you are directing artillery with a bursting/kill radius of 35 meters and a wound radius of 100m.

When directing artillery or mortar fire, the observer will call in corrections, up/down, left/right in meters. Mils make it easier to use smaller increments.
Posted by: scafool

Re: Recommendation for a decent compass - 03/28/10 02:33 PM

Not exactly milli-radians Russ. close though.
Nato Mils are layed out as 6,400 mils in a circle. I think the Swedes used 6,300 and the Russians used 6,000.
If it was actually milli-radians it would be 6,283

It helps to think of them more like %grade.
Surveyors often measure grade as a percentage instead of in degrees. 1% grade is one foot change in height over 100 feet of distance.
With mils at 1 kilometer distance 1 mil is 1 meter, or at 1,000 feet it is 1 foot.
Since you are using it on a compass mils can be read like degrees and you can relate them directly to a measured distance.
(It is accurate enough at narrow angles but it distorts as the angle gets wider. The problem is radians are measured along the arc of the circle but straight line measurements are tangents or chords of the circle. For large angles you need to correct using trig tables.)

This make it possible to do range corrections like JB says and you can also use it to estimate ranges to targets.

To explain that:
If you know that a man is really about 2 meters tall and he measures 2 mils tall in a telescopic sight then he is about 1,000 meters away.
You can use other objects like buildings or vehicles the same way.
If you look at a tall building you can assume 3.1 meters floor to floor for residential and 3.9 for office buildings.

Of course with a compass you have a hard time measuring heights but there are similar rules on horizontal measurements.
For example most transport truck trailers are 53 feet (16 meters) long.
If you have a few other common object sizes to use you can estimate ranges fairly accurately.

Remember that it isn't just for shooting but for any measurement at a distance. You can even use topo features instead of man made features if you have an accurate map.

I am not a user of rad, grad or mil measurements because I am usually working in degrees with lat and long.
However on a map with Easting and Northing (The Civilian UTM Grid Reference System or the Military Grid Reference System)
the grid on the map gives you the location as a distance measurement from the west going east and from the south going north.

Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/28/10 04:12 PM

Originally Posted By: scafool
Not exactly milli-radians Russ. close though.
Nato Mils are layed out as 6,400 mils in a circle. I think the Swedes used 6,300 and the Russians used 6,000.
If it was actually milli-radians it would be 6,283


Yes, until 2007, then we switched to 6400. Prior to the 6,300 division we had our own system called "streck" = roughly translates to "line". 1 streck is the horisontal distance of 1 meter when you you view it from a distance of 1 kilometer.

Posted by: NobodySpecial

Re: Recommendation for a decent compass - 03/28/10 04:49 PM

Originally Posted By: Russ
What is it with the Army and mils (Milliradian)?? Why don't they use degrees like everyone else?

It saves the artillery guys having to do sums (always a good idea with artillery guys)

A radian is an angle where the length of the circumference = radius.
So a milliradian is one part in 1000.
So at 1km a mil is one metre across, similarly if you know an object is 10m long and you measure it as 1mil you know it is 10km away.

Most militaries round off the milliradians, to eg. 6400 so that it's easier to mark off on a compass.



Posted by: jzmtl

Re: Recommendation for a decent compass - 03/30/10 06:36 AM

Originally Posted By: NobodySpecial
Originally Posted By: jzmtl
Suunto MC-2G on impulse buy. Having buyer's remorse now, I really don't need a compass that good.

Whats worse is they last a lifetime so you have a long time to remorse about it !


Well it didn't last long, this compass is going back to the store tomorrow. The declination/inclination marking is off by 2 degrees, I'm NOT happy consider its the most expensive compass many outdoor store carries.

If I can find one that's accurate I'll exchange one, but if not it'll be returned.
Posted by: KenK

Re: Recommendation for a decent compass - 03/30/10 12:29 PM

Do you man the marks were printed wrong?
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/30/10 10:14 PM

No, the declination scale on bottom of the capsule and the outer degree ring don't line up exactly. I.e. zero declination doesn't point exactly to south, but off by 1 or 2 degrees. What's even more weird is I went to the store again and all their stock is like this. So I'm not sure what's going on here, or if they are meant to be like this.
Posted by: KenK

Re: Recommendation for a decent compass - 03/31/10 12:02 AM

Hmmm, so you're saying that the declination scale zero degree mark on the back wasn't lined up with the bezel scale zero degree mark on the front?

I might recommend the Silva Expedition 15 (outside the U.S., I think) or the Brunton 15TDCL (inside the U.S.). It is made by Silva of Sweden.
Posted by: hikermor

Re: Recommendation for a decent compass - 03/31/10 12:02 AM

I pulled out my trusty MC-2D, essentially the same model you have, to see what the deal is. My declination and south line up precisely, or at least as well as my aged eyes can discern. My particular model is at least fifteen years old.

Now I can set the declination scale so that it does not point directly to south, by one degree, two degrees, or more. That is the purpose of the very small brass screw on the back of the compass ring (at least that is where it is on mine) and that is why there is that very tiny screwdriver on the lanyard. The idea is that I can set the declination to whatever value is appropriate for the region in which I am traveling.

If the compass ring and the declination scale are centered on the same point, and you can change the declination offset, I would think your compass is perfectly fine....

We may need to resort to pictures......
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/31/10 12:36 AM

Here's a pic to show what I mean. Ignore the orientation arrorw, it's set to my local declination.

If I draw a line from center of compass to the 0, +90 and -90 of the declination scale, it doesn't intersect with the corresponding S, E, W marking on outer ring, but off by 1 or 2 degrees. So either the vial or the outer ring is misaligned, and if I were to set the declination according to the scale, 0 wouldn't be quite 0, and my reading would be off by a degree or two, or am I over thinking it?


Posted by: Russ

Re: Recommendation for a decent compass - 03/31/10 01:23 AM

I had to pull out my MC-2G to do a valid comparison and I don't see it. My declination scale lines up perfectly with the compass scale. That must be a bad lot of MC-2G units. That said, I notice in the picture the scales at E, W and S are all off consistently ~+1/2 degree. What would that mean?
Posted by: scafool

Re: Recommendation for a decent compass - 03/31/10 04:15 AM

Maybe if you contact Brunton they will send you a better one because it does sound like you found a bad run of them.
http://www.brunton.com/faq.php?pr=Compasses
Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/31/10 12:18 PM

Sorry but I do not get it either, have you tried to adjust the scale as hikermor suggested?

Originally Posted By: Russ
I notice in the picture the scales at E, W and S are all off consistently ~+1/2 degree. What would that mean?


That would mean that someone has adjusted the compass to a declination of ~+1/2 degree.

--edit--
yes, the assembly is wrong
Posted by: scafool

Re: Recommendation for a decent compass - 03/31/10 12:42 PM

No, what Jzmtl is saying is right. His degree bezel and declination scale seem to be out of register.

On that model you adjust declination by moving the arrow that your needle is supposed to line up over.
The scale doesn't move relative to the bezel because it is part of the capsule base.

But again I am not sure if it is worth worrying about or if it is easier to just note it when setting your declination.

Like I have mentioned before, small hand held compasses are usually limited to about 2 degrees accuracy anyhow. It is both the local magnetic variation and the mechanical limitation of the instrument at work.
Hopefully small errors cancel instead of accumulate, which is why you try to eliminate systematic errors that would add up over repeated sightings.

For most work a compass like Jzmat has would be acceptable.
A 2 degree error works out to about 92 feet over a mile.


Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 03/31/10 01:03 PM

Yes, I see now, the "off" in your compass is actually annoying.
Mine isn't at all like that. The scale should be perfectly aligned.

a short video on declination setting
view from 2:13
http://compass-howto.com/%20/featured-videos/magnetic-declination/
Posted by: scafool

Re: Recommendation for a decent compass - 03/31/10 01:57 PM

Yes, I think I would find it annoying too if I had spent good money for a compass and found a built in error.
Even if it was a small error.
Posted by: KenK

Re: Recommendation for a decent compass - 03/31/10 02:03 PM

Originally Posted By: scafool
Maybe if you contact Brunton they will send you a better one because it does sound like you found a bad run of them.
http://www.brunton.com/faq.php?pr=Compasses


I doubt Brunton will send a new one because it was a Suunto MC-2G.

grin
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/31/10 02:11 PM

Originally Posted By: scafool

For most work a compass like Jzmat has would be acceptable.
A 2 degree error works out to about 92 feet over a mile.




I suppose, but consider how much the damn thing costs in Canada, it still bugs me. Going to the store over their stock again, will see if I can exchange a more accurate one.
Posted by: scafool

Re: Recommendation for a decent compass - 03/31/10 02:25 PM

Originally Posted By: KenK
Originally Posted By: scafool
Maybe if you contact Brunton they will send you a better one because it does sound like you found a bad run of them.
http://www.brunton.com/faq.php?pr=Compasses


I doubt Brunton will send a new one because it was a Suunto MC-2G.

grin

Oops, my bad. blush
I also made a misstatement on the 2 degree error. It should be for one degree.
Posted by: jzmtl

Re: Recommendation for a decent compass - 03/31/10 08:31 PM

Went back to the store, they let me picked the least misaligned one from the inventory no problem, still a tiny bit off but I can live with that.

They did seem to have a batch of bad product thou, I went to another store and their stock are all perfectly fine.

Now I just have to do something about the easily scratched plastic mirror.
Posted by: NobodySpecial

Re: Recommendation for a decent compass - 04/01/10 01:10 AM

Sorry about the compass, it's always annoying when you buy a precision instrument/tool and it's off.

But 1deg constant offset doesn't really matter, it's hard to use a hand bearing at that accuracy and depending on where you live the magnetic deviation can vary by that over a very small distance.
Posted by: kevingg

Re: Recommendation for a decent compass - 04/01/10 01:31 AM

I've got a Brunton 8099 pro; its crap in my opinion. huge bubbles formed on multiple occaisons, requiring replacement. the baseplate quickly faded to unreadable, the needle stuck, the bezel so loose it turned on its own. customer service was great and they always sent me new parts. finally I just shelved the thing and go with a $10 silva from Walmart. I've got a few in different places and never been happier!
Posted by: haertig

Re: Recommendation for a decent compass - 04/01/10 02:33 AM

Originally Posted By: jzmtl
Here's a pic to show what I mean. Ignore the orientation arrorw, it's set to my local declination.

Did you try grabbing the bezel to hold it firmly in place, then pinching the capsule (front to back) and turning it within the bezel to the proper orientation? Normally the capsule will spin in sync with the bezel, but that doesn't mean you can't make them turn independantly of each other using a firm grip.
Posted by: jzmtl

Re: Recommendation for a decent compass - 04/01/10 02:44 AM

Originally Posted By: haertig
Originally Posted By: jzmtl
Here's a pic to show what I mean. Ignore the orientation arrorw, it's set to my local declination.

Did you try grabbing the bezel to hold it firmly in place, then pinching the capsule (front to back) and turning it within the bezel to the proper orientation? Normally the capsule will spin in sync with the bezel, but that doesn't mean you can't make them turn independantly of each other using a firm grip.


I grabbed the replacement to try, no go, it's glued in there tight.
Posted by: comms

Re: Recommendation for a decent compass - 04/01/10 05:37 AM

I own several compasses and still my fav is a 'real' Silva Ranger that is many many years old. I have a Brunton Eclipse, the Adventure Racing model. I like the set up as a baseplate compass and the way the Eclipse system works (circle in a circle)however as many people have stated a large bubble develops. I have researched online and have seen the gamut from automatic return for defect to it doesn't do any anything but its a visual doubt to reliability. I tend to fall into the later category.

I have always wanted a pocket compass or gentlemens compass. The old time models just visually appeal to me and I like the idea of handing something like that down to my son, like a good knife or watch. I had the chance to hold a Davey medium model and it felt like it weighed two pounds in my hand and somewhat cooled me to the idea.

But I never miss a chance to shop for compasses
Posted by: KenK

Re: Recommendation for a decent compass - 04/01/10 01:14 PM

... and just to clarify, at least in the U.S., the 'real' Silva Ranger - made by Silva of Sweden - is sold by Brunton as the 15TDCL.

In the U.S. the one labeled as "Silva" is NOT made by Silva of Sweden - who made that original Ranger compass.
Posted by: jzmtl

Re: Recommendation for a decent compass - 04/01/10 06:41 PM

Are the real Silva sold by Brunton still made in Sweden? I've read some reviews that indicate they are now made in Asia.

The American Silva is actually made by Suunto, in either India or Philippines.
Posted by: BorkBorkBork

Re: Recommendation for a decent compass - 04/02/10 09:19 AM

Originally Posted By: scafool
[quote=KenK][quote=scafool]Maybe if you contact
Oops, my bad. blush
I also made a misstatement on the 2 degree error. It should be for one degree.


Sorry, but that isn't correct either.

the error for 1 degree is 1/60:th of the distance travelled.

1 mile (US) = 5280 feet
5280/60= 88 feet for a 1 degree error.
Posted by: scafool

Re: Recommendation for a decent compass - 04/02/10 01:26 PM

I am glad you brought up the 1/60 rule Bork. A lot of people have never heard of it.
The 1/60 rule is a very useful approximation for course corrections, especially for pilots in small planes.
They usually count it over 60 miles and being miles off course.

The 1/60 rule simplifies the calculation, but the result you get is the distance off for slightly under one degree instead of a full degree.
(0.96 degrees)

If you use the circle calculation for the arc of a circle you get
2pi*5280/360 = 92.1533845
It is still an approximation because you are measuring the arc instead of the straight line(chord) but it is a bit closer.

If you use the sine of 1 degree you get 92.148706 feet
If you use the tangent of 1 degree you get 92.1627428 feet

The 1/60 rule is a lot easier to use though, and the results it gives are fine for most uses.
If we were able to get close enough with our hand held compasses that being 4 feet off in a mile mattered we should be very pleased with ourselves indeed.