If I only occasionally needed to “find north” to roughly orient a map or to follow a short bearing, a basic magnetic compass like the Silva Starter would be sufficient.
But I rely more heavily on my compass than that, since I often backpack in low-use areas where signage is unreliable and trails can be intermittent, as well as off-trail. The compass is a core component of my navigation toolkit, best used in partnership with my topographic maps and GPS sport watch (a combined timepiece, altimeter, and auto dead-reckoner).
For several years I have preferred the Suunto M-3G Global Compass, which is a premium model that I would recommend to other heavy compass users, current or aspiring.
Long-term Review: Suunto M-3G Global Compass
For my purposes the M-3G Global hits the sweetspot. Key specs:
- Adjustable declination
- No sighting mirror
- Global needle
- 1.6 ounces (45 grams), with stock lanyard
The M-3G’s price is high but attainable, and I’d encourage readers to think about it like a premium sleeping bag: buy it now, take care of it, and replace it in 10 or 20 years.
A skilled photographer with a crappy camera will take better photos than an ametueur with a pro-level model. The same is true about navigators and compasses. A premium compass is not necessary to navigate expertly, but it is more convenient, efficient, and pleasant to use.
Without this feature, it is necessary to manually adjust for declination, or the angular difference between true north and magnetic north. The adjustable declination feature minimizes errors, especially when fatigued.
No sighting mirror
A sighting mirror is primarily designed to improve accuracy when finding or transferring a bearing in the field, because you don’t have to shift your eyes as much. Incidentally, it also protects the top of the compass.
Personally, I’m unsold by these supposed advantages, and do not believe that a sighting mirror is worth the added weight or expense. Without one, I can be equally accurate with negligible inconvenience, and I can protect the compass simply in how I store it. The M-3G remains ultralight, at 1.6 ounces with the stock lanyard.
The standout feature of the M-3G is its global needle. Even if you are not planning to backpack in Antarctica or Ellesmere Island, where most magnetic compasses go haywire, you will still benefit.
The compass need not be perfectly level for the global needle to rotate. In fact, it can be pitched at a 20-degree angle, and the global needle will still work flawlessly. This makes the M-3G very responsive. Finding and transferring bearings in the field is slower and more tedious with compasses that do not have a global needle.
Watch this video to see the difference:
One important variable in avalanche risk is slope angle. The M-3G has a built-in clinometer so that it can be accurately estimated.
In 2013 Suunto sent me ten M-3G compasses for loaning out on my guided trips. They were used on about 40 trips, and normally each one of them was checked out.
My remaining seven show signs of wear, but they have fared well overall. At some point most of them were dropped in fine Utah sand, subjected to a night-long downpour outside a tent, stepped or slept on, or jammed into a pocket with hard and sharp objects. They are all still operable: no bubbles in bezels, fairly smooth operation (with some help from a dab of olive oil after desert trips), and legible imprinting.
For occasional and basic use, an inexpensive baseplate compass is sufficient. It will not feature adjustable declination or a global needle. Consider the:
For more extensive use but without the price tag of the M-3G, select a compass with adjustable declination but without a global needle. Consider the:
How to use your compass
If you are not yet proficient in operating a compass, check out these posts and watch these videos:
- How to adjust for declination and orient a map
- How to find and transfer bearings in the field and on a map
What compass do you own and what are your thoughts? If you are in the market, what questions do you have about them?
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