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Long-term Review: Suunto M-3G Global Compass || Fast, adjustable & ultralight

In a trail-less wilderness like Grand Staircase-Escalante, I use my magnetic compass extensively.

In a trail-less wilderness like Grand Staircase-Escalante, I use my magnetic compass extensively.

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.


Please support this review by purchasing the M-3G (or another compass) from Amazon or from one of these select vendors:


Feature set

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.

Adjustable declination

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.

Global Needle

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:

Clinometer

One important variable in avalanche risk is slope angle. The M-3G has a built-in clinometer so that it can be accurately estimated.

Durability

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.

My demo compasses have fared well over the course of about 40 guided trips.

My demo compasses have fared well over the course of about 40 guided trips.

Alternative recommendations

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:

Good, better, best. The Silva Starter (left) is sufficient for occasional and basic use. The Suunto M3-G (right) is best for extensive navigation. And the Suunto M3-D Leader (center, old version) is a more budget-friendly alternative than the M3-G but more advanced than the Starter.

Good, better, best. The Silva Starter (left, old version) is sufficient for occasional and basic use. The Suunto M-3G (right) is best for extensive navigation. And the Suunto M-2 (center, similar to the M-3D Leader) is a more budget-friendly alternative than the M-3G but more advanced than the Starter.

How to use your compass

If you are not yet proficient in operating a compass, check out these posts and watch these videos:

What compass do you own and what are your thoughts? If you are in the market, what questions do you have about them?


Disclosure. This website is supported mostly through affiliate marketing, whereby for referral traffic I receive a small commission from select vendors, at no cost to the reader. This post contains affiliate links. Thanks for your support.

9 Responses to Long-term Review: Suunto M-3G Global Compass || Fast, adjustable & ultralight

  1. Bob S. November 28, 2016 at 5:42 pm #

    I’ve been using a Silva Ranger Ultra for 10+ years. It’s fine for on-trail use but over the years the dial developed some slop so it’s probably 1 to 2 degrees off.

    I prefer to leave the adjustable declination set to zero and do the math rather than adjust the declination on the compass. I guess whatever technique works best for you is the one to use.

    Although map and compass skills are essential for anyone venturing into the great outdoors, I’m pretty sure the Donner Party would have preferred to use a GPS…

  2. Walter Underwood November 28, 2016 at 7:10 pm #

    Back in the 1970’s, my dad had a Silva Ranger with a mirror. We didn’t need the extra precision, but it sure was handy for figuring out how much his beard had grown out or for getting a look at the hot spot on the bottom of the big toe. Of course, it was a few days into each of three trips before we remembered we had a mirror. Sigh.

    So I still carry a compass with a mirror, because it is kinda useful on the compass and very useful for other things.

    Try carrying a compass with a mirror, then remembering that you have a mirror in your pack. You might like it.

    But the Suunto M-3D is a great compass.

    • Andrew Skurka November 28, 2016 at 8:04 pm #

      Love comments that start with, “Back in the 1970’s…”

      I’m surprised at how often I have felt like I needed a compass. And when you really need one, you really do. You can take a selfie of yourself, but the on-camera resolution is usually not good enough to see what is going on.

  3. spelt November 29, 2016 at 7:02 am #

    I use an M-2. It has a bubble after only a few years, but it still works.

    • Alex November 29, 2016 at 12:15 pm #

      After 7 years of use my M-2 developed a bubble tooand has now grown to the point where it impedes the rotation of the needle. I still have it to for my 6 year old son to learn on.

      This summer I picked up a M-3 D on sale and agree that it’s a good compass. I appreciate the longer baseplate over the M-2 and the bezel rotates smoothly with no wobble. The adjustable declination mechanism works fine, but can be a bit hard to set accurately due to the tiny 2 degrees tick marks-same on the M-2.

      • Andrew Skurka November 29, 2016 at 1:22 pm #

        Want to clarify: Do you have the M-3D or the M-3G? They are on the same chassis, but the needle action is so different that they shoukd not be confused.

  4. Alex November 29, 2016 at 5:44 pm #

    I have the M-3 D. I checked out the G (Global) and was impressed with how quickly the needle righted itself, but just couldn’t justify the price.

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