BACKGROUND
I don't think I need to sell anyone on the ideal that a compass is an important tool for land navigation. It's also just a nice thing to have on an everday basis, as I find myself often wondering which way is north.
Almost as important as having a compass is having it be easily accessible. Any tool that is difficult enough to use is not worth using. So since at least the second world war, people have been mounting their compasses to their wrist for quick and easy access.
This trend still lives on, though mostly only in niche circles. Suunto currently makes a few wrist compasses, notably the M9 (more on this later). I liked the idea of the M9, but wondered this: I wear a watch every day, so instead of using a standalone strap to mount the M9 compass to my wrist, can I instead mount it to the existing strap on my watch?
Turns out, Suunto thought of that too. They make a model called the Clipper, which is a tiny button sized compass that has a slot through the housing that you can run your watchband through, combining your wrist watch and your wrist compass into one unit. What a time to be alive.
OFF-THE-SHELF OPTIONS
So I bought myself a Suunto Clipper (and also a similar product, the SunCompany GoCompass) to try out mounted to my G Shock GW-500A.
The results were not good. They fit the watch fine, but they don't give accurate or precise bearings. My layman's explanation is this: the dials don't have enough mass to overcome their friction within the casing and spin freely. Obviously spinning freely is necessary to point in the right direction. If you've ever had to flick a compass to get it "unstuck," you know what I'm talking about. The larger a compass is, the more mass its dial has, and the less this issue occurs. These compasses are just fundamentally too small to have the mass to move freely, and thus, never seem to point in the right direction. You can flick them all day, but they'll always give different bearings, none of which you'd want to trust. Furthermore, the SunCompany one actually broke after about 6 months, when the entire liquid filled chamber fell off the housing and was lost.
DIY MOUNTING
So I needed a bigger compass, one with more mass. I returned to the Suunto M9. A friend had one and said that it was relatively reliable. So I bought one and started to play around with ways to mount it to my G Shock wristband. At first I tried sewing this weird hypalon mounting loop. Worked, but was wobbly and a pain to make. Then a friend recommended I simply tie it on with (my favorite) Atwood micro cord. And so we arrive to this:
So how does it perform? Pretty damn good. The compass is WAY more reliable. It needs to be held away from the body and metal objects, and flicked once in a while, but it consistently reads north correctly within a few degrees (take note of "within a few degrees," I use this mainly to find north and double check headings, for shooting precise bearings I still take out my Silva Ranger compass). The larger body makes it easier to read, and it's also glow in the dark. It has also lasted about 2 years now with no ill effects. It's a great conversation piece, and I always get people asking me if I'm wearing two watches on one band. If it had a downside, I'd say that it's pretty bulky and can get caught when removing shirts/jackets with tight sleeves, but that's a relatively minor issue. Lastly, I get one step closer to looking like Artyom from Metro 2033.
HOW TO
So to do this yourself, you need:
A wrist watch that does NOT have a lot of metal in it. We tried with a chunky metal watch and it throws the compass out of wack
A Suunto M9 compass (preferred) or one of the Chinese knockoff "Tactical Wrist Compasses" from ebay, pictured above on the right
A foot or two of Atwood Micro Cord
First, remove the wrist compass from the strap it comes with. For a Suunto you just pull out the velcro strap, and for the chinese knockoff you slice the strap off with scissors. Be sure to leave the strap mounting points intact.
Next, line your compass up on the band of your watch (as close to the bottom of the watch body as possible), then take your micro cord and go to town. Below you can see two different ways of tying it on. There's no right or wrong way. Just secure the top and bottom ends of the compass to the wrist strap as tight as possible, then securely tie off the cord, and trim and fuse the ends.
There you go, done. It holds much more securely than you'd think, and it's survived two years of daily carry, getting smashed off of random objects, and never once breaking or coming loose. Give it a shot, and especially if you do landnav, you'll LOVE how convenient it is when you need to double check your bearing.