smallest compass w/magnetic declination adjustment?

Check out the Brunton TruArc 3 Compass – it has a deviation adjust dial and only weighs 0.8 ounces if you remove the housing from the base plate.

ooh! Thanks!

East is Least, West is Best

Like anything in life, becoming expert at something takes practice. Little sayings, like the one above, often help us learn and remember. And with practice, those sayings no longer become necessary to remember.

In the military I learned how to navigate with a non-adjustable compass and was expert navigating in jungles, at night, or in snow storms in the mountains. When I became a civilian and was backpacking for the next 40 years I never really needed a compass — map association worked fine. A few years ago I found myself in a maze of desert canyons and really needed expert compass skills, but my skills had deteriorated with the lack of use or practice. I was able to eventually find my way, but learned an important lesson; to remain competent with map & compass one has to practice.

Although I have a simple baseplate compass and an adjustable baseplate compass, I went back to a lensatic compass and a map protractor. I reviewed the techniques I learned in the late 60’s and practiced. Now each year I go places that are somewhat difficult to navigate and practice. Should I get in a position where I absolutely need a compass, I don’t want to risk rusty skills, no matter what compass is available.

Here is a two part article I wrote on how to operate with any compass. I try to explain how declination works and how to remember when to add or subtract declination. Buy a quality compass. The cheap ones develop bubbles and are next to useless. Also, a compass usually stays in the pack and a cheap one is subject to potential damage.

Buy a quality compass. The cheap ones develop bubbles and are next to useless.

Also pack your compass where it won’t get banged against rocks or dropped on the ground – not around your neck, in a pocket (unless you’re using it), loose in a backpack top lid (falls out easy) or inside a kayak dry bag that gets stuffed into hatches or thrown onto beaches. After having multiple compasses develop bubbles, including an expensive one, there seems to be a correlation between physical abuse and cracks/bubbles.

It’s good to have multiple compasses for different needs. For groomed trail hiking (JMT, PCT sections, etc), a small, light good quality compass is fine. If you’re going off trail or hiking in country where it’s hard to get a fix and orient by simply looking at a map and the surroundings, then a more accurate high quality compass (mirror and sight) is important. And if you know there will be challenging navigation required (i.e. kayak trips with many flat islands or inlets, or extended hiking in flat country off trail with few visible handrails or baselines), then a GPS or other device to show your position is a good confirmation tool.

Here’s a good book to use to brush up on your navigation skills (Wilderness Navigation by Burns and Burns):

http://amzn.to/2w1cxuc

Eh, opinions differ. I buy the smallest and least expensive BRAND-name compass I can find and hang it around my neck where I can get at it easily and USE IT. A compass in my pack is of little use to me.

Bubbles – so what? They do not affect the use of the compass unless they are huge. The only purpose of the liquid in the compass is to damp the vibration of the needle and to lubricate the pivot. In fact, having a small bubble in your compass gives you a free horizon detector for estimating the angle of a climb.

Mind you, tiny compasses are not all that good. You need a needle of about 35 mm length (in liquid) for ease of use. More expensive compasses give me no greater accuracy in the field, and mirror unit are just excess weight and cost. Navigation in the field with a topo map is NOT the same as taking bearings for artillery use.

Ymmv
Cheers

Another vote for the Brunton TruArc 3, although most of the time a small tag compass will do for my needs.

I’ve had a few Suuntos develop bubbles that are large enough to compromise their performance even though they were not abused or handled roughly. Photo below of a bubble in a MC-2G at an elevation of only 1100 ft… imagine what it would look like at 11,000 ft! Suunto replaced it, but with the MC-2 not the 2G.

Bob

That bubble would barely change in size in going from 1,000 to 11,000′. It CAN’T change in size unless the liquid compresses or the chamber increases in size. Liquids do not compress like that, and any change in the size of the chamber would be miniscule.

Me, I would not have worried about a tiny bubble like that.

Cheers

I got a bubble at 11000 feet, actually that’s just when I noticed, and it was gone by 8000. I simply assumed that my readings would be a few degrees off — human error or mechanical — so I’d navigate “to the stream, follow it to the lake, and take the pass on the North shore.”

I guess I navigate expecting some degree of error. The compass kept me from going South into a lovely valley that I’ll return to, it kept me on-route over the next pass — to the North.

“mirror units are just excess weight and cost”

Until you bite into a prickly pear cactus fruit.

Or need to treat some other first-aid situation on your face.

Or need to groom yourself to hitch-hike home.

Not that I’ve done all of those, at times, or anything.

A square foot of space blanket would be a whole lot lighter …

Cheers

Bob, is that green tab your homemade declination correction?

Regarding compasses with bubbles, I tilt them just enough to move the bubble to the east or west (i.e., no longer bumping the needle).  It doesn’t take much.

Regarding declination, the best mnemonic I’ve found so far is “LARS”: Left add; right subtract.  It works in concert with the declination diagram: you put your finger or other pointer on the tip of the arrow matching the type of North your starting number is based on, and move it left or right to the arrow representing the type of North you want.

Example: you’ve plotted a course of 55° on your map by aligning your protractor with the gridlines.  You now want to adjust your compass to walk that bearing, and your local declination is 12° East.  So, on the declination diagram you point first to the tip of the grid north arrow, then slide your pointer to the tip of the magnetic north arrow.

Since the declination is East, you hopefully slid the pointer to the right (unless you’ve held the map upside down).  Per “LARS” you would then subtract the 12° of declination and thus adjust your compass to walk a bearing of 43° magnetic.  A benefit is that this also works in reverse, e.g. if you want to plot a magnetic azimuth on your map.

Declination – we have it easy with our Australian topo maps. Very prominently, usually at the middle bottom, there is a common N/S/E/W diagram (aligned more or less to the grip lines) with the magnetic declination shown with a separate arrow. We stick our compass on that, rotate the topo to align the compass to the declination arrow on the topo, and carry on from there. I doubt many walkers here ever bother remembering whether to add or subtract.

Cheers

Quite a few times I’ve seen bubble size increase substantially due to altitude so I would humbly suggest there is some mechanism by which this can occur, and not just temperature change.

I can count on one hand the times I’ve truly needed a precise bearing for navigation (outside of USAF survival school), with 2 or 3 of those being in whiteout conditions where a few degrees of error could have made for a bad situation. Nowadays, I use my little tag compass maybe a couple of times per year as a simple “sanity check” on overcast days to make sure I’m heading in the correct direction.

In any event, bubbles that size annoy me and IMHO should not be a ‘feature’ of a compass priced at $85 or so.

Jeremy, those green stripes (there are 2, for judging parallax error when using the mirror) were factory standard on MC-2G models of that vintage, which was about 1996 or so. At some point Suunto started making them white.

In any event, bubbles that size annoy me and IMHO should not be a ‘feature’ of a compass priced at $85 or so.
Can’t argue with that! All they need is a better O-ring for the seal. Cost an extra $0.50.

I did try refilling a half-empty compass at one stage, but even the lightest oil was far too viscous. I am left to wonder what ‘they’ use as a liquid? Does anyone know?

Cheers

Mineral oil?

Some compasses use a sapphire jewel bearing so bubbles are not a concern.

Regarding declination, the best mnemonic I’ve found so far is “LARS”: Left add; right subtract.

@requiem, I’ve always appreciated your knowledge of navigation!

That mnemonic works… whatever helps one to rember. But we need to keep in mind that “from map to field” is opposite of “from field to map.” Also some USGS maps are pretty old, so the declination can be off by 2 or 3 degrees. A 3 degree error will put you off course nearly 300 feet in one mile.

Thanks Nick!

That’s a good point about the declination information getting a bit stale.  A flip from East to West declination (fortunately not too common) would require re-sketching the diagram and not just noting the new numbers.

Even so, as long as one uses the pointer trick, the “map to field” and “field to map” switch between adding and subtracting is built-in: when going from field (magnetic) to map (grid), you’d first point to the tip of the magnetic arrow on the diagram and then slide left or right to the grid arrow.

Edit: Thinking about it more, really all the magic is with the “point at the diagram” bit; both mnemonics work with it.

-J

A 3 degree error will put you off course nearly 300 feet in one mile.
This might be a problem in dead flat country with no hills or contours, but that is fairly rare around here. We USE the local terrain as part of the navigation – creeks, hills, etc.

Cheers

If you need a better declination than what your map shows, punch the lat/long into this website and it will get you the declination for the current, or any selected date.

https://www.ngdc.noaa.gov/geomag-web/#declination

Regarding the bubbles that form in the compass housing, I haven’t done it myself, but have been told that putting the compass in the oven (at a temp that won’t melt it) will get the bubble to dissolve back into the liquid. Was explained to me that the bubble forming wasn’t air leaking into the compass but gas coming out of solution at the lower atmospheric pressures associated with higher altitude.

Curious if anyone else can confirm or deny this.

Also, regarding the original question:

http://www.suunto.com/en-US/Products/Compasses/Suunto-Clipper/Suunto-Clipper-LB-NH-Compass/

This tiny thing has a declination setting of sorts. Not precise, but will take care of gross declination and get you headed generally in the right direction.

Silva website FAQ:

My Silva compass has a bubble in the fluid. What should I do?

We intend that our compasses are free of bubbles; however, if a small bubble forms in the liquid-filled capsule, it has no influence on the accuracy of the compass. Its appearance and disappearance are due to changes in temperature and atmospheric pressure. If a bubble larger than 1/4″ in diameter appears, it is probably the result of a leaking capsule, usually caused by some form of shock damage, and the capsule will have to be replaced. In that case, just call our customer satisfaction department for a return authorization number and shipping address.

Cheers

That’s a nifty little thingy.

My own experience with one of those ‘mini’ compasses is that they are rather tricky to use. You have to get them dead level and still before you can rely on them. But … it was not a Suunto, so ?

Cheers

LOL at $20 I’d hope it’s somewhat usable! :-D