Compasses

[Johnnie]

I'd like to buy a compass but I'm not sure if they're all the same. I already have a GPS but I'd like to buy a hand held or true mountable compass. There are cheap compasses for $5 and they can also get pretty expensive too.

Do you guys recommend a specific brand or does it even matter?

John

[mudferret]

Get yourself a Silva, Bruntons are nice, but expensive and most people are clueless about how to actually use them. Make sure you get a Silva with a clinometer.

Link to a good Silva (http://www.getreadygear.com/index.asp?PageAction=VIEWPROD&ProdID=85)(you can find them for cheaper)

[keepitonall4s]

Bushnell has on out. I think its called backtracker or something like that. It runs like 60-80 bucks

[Scootn2nature]

Make sure it was declinated in your region of travel

[tacosupreme]

Make sure it was declinated in your region of travel

isn't that what the magnetic deviation doohicky is for on the bottom of a map? Also it changes .5* a year or so, depending on location so a declinated compass is only good for a short period of time. Even if you're handy with a compass you can only get about +-3* anyway. Good enough for navigation I suppose.

[NROSS]

isn't that what the magnetic deviation doohicky is for on the bottom of a map? Also it changes .5* a year or so, depending on location so a declinated compass is only good for a short period of time. Even if you're handy with a compass you can only get about +-3* anyway. Good enough for navigation I suppose.


As far as declination goes it will vary from compass to compass and area to area.You should also keep in mind where your using it i.e. standing next to your truck, in your truck,under or near to power lines or in a open area with no magnetic disturbances around. Once you get a compass you should see how different surroundings affect it. A good place to check declination is a local airport, the numbers at the end of the runway are true north. I personally like Suunto compasses. Regardless how much you spend or don't spend you need to learn the limitations of your compass and what effects your surroundings have on it. Good luck.

Neil
Reformed surveyor

[WallyP226]

I have found the compasses that have adjustable declination and a site line to be the most useful. The site line helps set visual plot points from a map, the declination helps a compass be a little more accurate to a given area.

It is true, that a lot of things can make a compass go hay wire. When I was in Alaska, there are places where the compass needle spins in circles, or changes the compass direction until away from that area.

:2cents:

Wally

[Topper]

Get yourself a Silva Ranger (http://media.rei.com/media/408031Lrg.jpg) or something similar. Suunto and Brunton both make similar models.

A small bubble level on the baseplate of the compass it can be very handy for keeping the compass level for reading.

As Mudferret said, do not overspend and buy one of these

http://www.uwm.edu/Course/geosci697/sections/new%20brunton.jpg

They have their uses, but orienteering isn't one of them.

The declination is the angle between the North Pole and the Magnetic North Pole from the point you are standing at.

It will vary significantly from region to region and the compass above is adjustable for declination, so you can set it yourself.

Here are a couple of sites you can use to find the declination. Enter a general Lat/Long for the area where you will be using the compass and a rough date and voila, it spits out the declination. On the second link you can even enter a zip code and a date.

http://geomag.nrcan.gc.ca/apps/mdcal-eng.php

http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

Because the magnetic pole is wandering, the angle between it and the North Pole changes with time.

Use cation when using the charts fro declination printed on maps and the rate of change in the declination each year, as that rate of change may not be accurate on older maps.

As someone else noted, always remember that a compass needle is a magnet. If it is in the vicinity of metal it can and will be swayed. A watch on your wrist, a camera strapped to your chest or a belt buckle is enough to influence the compass.

If you are travelling internationally you need to remember that compasses designed for the northern hemisphere do not work well in the southern hemisphere and may have some issues in equatorial latitudes.

[Topper]

I have found the compasses that have adjustable declination and a site line to be the most useful. The site line helps set visual plot points from a map, the declination helps a compass be a little more accurate to a given area.

It is true, that a lot of things can make a compass go hay wire. When I was in Alaska, there are places where the compass needle spins in circles, or changes the compass direction until away from that area.

:2cents:

Wally

In all likelihood you were near an iron rich rock formation.

[Johnnie]

Wow, I didn't realize compasses could get so complicated. I'll have to figure out my needs and budget. I'm really just looking for something basic while I'm out in the desert. I would like to know which way is which so I could figure out my way back if necessary.

[Topper]

Wow, I didn't realize compasses could get so complicated. I'll have to figure out my needs and budget. I'm really just looking for something basic while I'm out in the desert. I would like to know which way is which so I could figure out my way back if necessary.

Silva Ranger and a map.

Set the declination for the desert area where you wheel and forget about it.

All the rest is stuff you need to consider so that you are not going in circles.

[nimrod712]

I own Silva, Brunton, Suunto, and the old military style.
My favorite is definitely the Suunto.:2cents:

[Roadtrip12]

I have an Airguide mounted on the dash of my truck. Not too scientific, but I need to know the basic N*S*E*W orientation when I'm driving!

[Jomentum]

Cheap liquid filled keyring under 30 bucks
http://www.thecompassstore.com/trailpilot2.html


Before I bought My nav system, I still use mine:
http://garmn.factoryoutletstore.com/images/CatalogItemVariation/3554/Garmin-Etrex-Legend-010-00256-00-img3.jpg
$ 149.99 http://garmn.factoryoutletstore.com/details/1661-2897/Garmin-eTrex-Handheld-GPS-eTrex-Legend.html

[SAR_Squid79]

In the military we always carry 2 compasses. For 2 reasons:

#1 - Two is one; one is none. You always need a backup - even for your backup!
#2 - Because it's easier to have 1 compass for working on your map, and 1 for actually navigating.


Link to a good Silva (http://www.getreadygear.com/index.asp?PageAction=VIEWPROD&ProdID=85)(you can find them for cheaper)
The compass linked above is the "mapping" compass we use - that I currently have on my vest.

The "field" compass we use is this one: (can't kill it)
http://store.cammenga.com/scripts/prodView.asp?idproduct=47

...and make sure you have one of these:
http://www.rangerjoes.com/protractor-ranger-joes-p-329.html

...and remember - a compass is pretty much useless without a map!

[WallyP226]

In the military we always carry 2 compasses. For 2 reasons:

#The "field" compass we use is this one: (can't kill it)
http://store.cammenga.com/scripts/prodView.asp?idproduct=47

...and remember - a compass is pretty much useless without a map!

Thats the compass I have. I have not looked at in years, but as soon as I saw the compass in the link, I knew that was the one I have. Mine has survived for almost 20 years. Many a backpacking trip in Alaska, Colorado, Utah, Washington, Oregon, and of course Missouri.

Good point about maps.

Wally

[adkfreeridex]

at 400-500 bucks for one of these they are very pricey. but it came to mind when i read this thread. we used them all through college to take dip/strike readings on rock layers. i figure that they would make a very good expo compass because it can also accurately read slope angles. this could be very useful when you gotta go up something that is steep and off-camber. plus you can make accurate geological notes in the process....but still a crap load of money. they are fun to play with though:
brunton pocket transit
http://www.brunton.com/images/catalog/5008_Transit.jpg

[adkfreeridex]

at 400-500 bucks for one of these they are very pricey. but it came to mind when i read this thread. we used them all through college to take dip/strike readings on rock layers. i figure that they would make a very good expo compass because it can also accurately read slope angles. this could be very useful when you gotta go up something that is steep and off-camber. plus you can make accurate geological notes in the process....but still a crap load of money. they are fun to play with though:
brunton pocket transit
http://www.brunton.com/images/catalog/5008_Transit.jpg

[frgtwn]

" A good place to check declination is a local airport, the numbers at the end of the runway are true north." NROSS

The numbers at the end of a runway reflect the degrees from magnetic north. Also, they are only delineated in 10 degree increments. So, the runway numbers can vary up to about 5 degrees from the magnetic heading.

I once heard a ham radio discussion on a repeater system where two hams had both flown into a certain runway, and they disagreed about the numbers. They turned out to both be correct, as the numbers had been changed during a resurfacing or repainting as the declination had moved slightly and a new survey changed the numbers.

Short answer: the numbers are useful but not accurate.