If you take a compass navigation class, the instructor is likely to teach you how to translate between magnetic bearings and “true” bearings, despite the fact that the grid lines on almost every map printed today are based on true north. One of the key reasons for doing this is to ensure that hikers who have compasses with declination adjustments can communicate with hikers who have compasses without them.
In practice, I find switching between map bearings and magnetic bearings to be unnecessarily taxing on my brain, especially when I need to do it in twilight during a bushwhack in winter. So I own a Suunto M-3 compass with a declination adjustment and do all of my planning and field navigation based on map north, and so do most of the hikers I hike with.
But I am curious whether other people prefer doing the math or are lazy like me.
My personal compass does have a declination adjustment. It’s invaluable for those times route-finding while tired, in poor conditions, or just to avoid sloppy math.
In my line of work, however, I more often than not teach folks on compasses without declination adjustment. Better to learn the rules first, then learn how to shortcut them, rather than the other way around. If I’m using my personal compass in that situation I’ll often reset the adjustment to 0 both for solidarity and practice.
I had a Silva Ranger which I loved, but it developed a large bubble and I returned it to REI. Got a a Suunto MC-2G as a replacement which has worked fine so far.
I often wonder whether teaching people about magnetic north and the difference between it and true north makes learning to use a compass more intimidating. If you can compose a class to all use the same compass with a declination adjustment, why not teach them map north first with a declination adjusted compass, get them hooked on the miraculous accuracy of compass navigation, and then after they see it’s utility, show the the ancient craft of magnetic bearings and translating between the two.
Just a thought. All too often we have students for less than two days of instruction, and what I really want them to do is to understand how to use a map and compass together as quickly and expertly as possible. Teaching both bearing systems gets in the way of that and introduces a lot of unnecessary confusion which can turn students off. It’s not something I do today, but have been pondering in order to teach very basic skills more quickly.
I’ve done it both ways, and I think it can greatly depend on the environment in which it’s being taught. The Mountaineers out here require students in their navigation courses to have an adjustable compass. The course is an evening session to learn maps and bearings followed by a full day session shooting and following bearings outside. To have an adjustable compass there I think makes the most sense as the learning curve is pretty steep for that time frame.
The situations where I haven’t used adjustable compasses are on extended wilderness trips where students are working daily with navigation and have constant instructor-student contact over longer periods. It’s easier to get them hooked on it when they don’t have a choice :)
So basically I agree with you, adjustable would be the way to go to get people started in those shorter sessions.
Ben – I really appreciate your sharing that with me. It’s something I’ve always wondered about for teaching purposes as I have been in situations where a shorter form course would be far more useful than jamming the longer curriculum into too little time and too little practice.
I live in the land of +14º declination. My compasses are set, then reset when I go to another part of the state.
I have two Silva Ranger compasses. One was my dad’s, so dates from the late 1960’s. I also have a couple of other smaller ones.
I have an Autohelm Personal Compass that uses a magnetic fluxgate. It is extremely accurate, but only if you hold it precisely level. I’m pretty sure that it does not have a declination adjustment.
My phone has a compass, too.
This website will show your declination, probably especially useful from a phone: https://www.ngdc.noaa.gov/geomag-web/calculators/mobileDeclination
For the weight-conscious, the Suunto M3 series have a declination adjustment and weigh 1.6 ounces (44g).
What is a Suunto M-10? I can’t find that model anywhere, only an A-10.
Typo – should be M3
I have declination adjustment on my compass, but don’t use it, i.e. it’s set to zero.
Yes my compasses have declination adjustments….
I have a Suunto M3 Global Needle and a Silva Ranger, I
prefer the M3.
Declination is always changing. I have an old Silva Ranger from 30+ years ago that works great on maps and stuff. But, I rarely need to use it that way. I don’t think I have carried it for over 20 years. Generally, I pick a marker (peak, sometimes a stream comfluance) and shoot off a bit. This is generally about the limit I can do bushwacking, so the declination matters little. I line up my map with the terrain I can see, then take a bearing on my compass. So, all readings are fairly relative to my compass. (I often bushwack into areas for camps,) I dropped it and went through a series of smaller, lighter compasses. I now carry a $3 cheapo. It works as well as any, except for map plotting.
Unfortunatly, most of the High Peaks areas have mineral deposits of iron ore that makes compasses behave badly. In one area in particular, I found myself about 20-degrees off from where I wanted to go. About a 100yd further on it was close to on again. Plotting an accurate bushwack is nearly impossible under those conditions.
I usually figure about 13-degrees declination. When I first got the Silva, I was at 11.5-degrees. For Baxter Park several years ago, I was told around 17-degrees. For Lackawana I was told around 10-degrees. The point is, it changes over time, and, with location. It is a wonder that any mapping done before satelites was as close to accurate as it was.
No, the one I carry does NOT have a declination adjustment. Nor do I keep up with the current declinations. Do I need absolute accuracy? No. Sun, stars, map features, trails & forks, are fairly constant and I can usually pick out my generally “north” from the terrain. I keep the compass for more definitive stuff, like locating my camp. Or, finding my way out to a trail.
I’ve always wondered why things were not the other way around.
Since maps with which you’d use a compass are pretty localized, why not have the grid lines aligned with the magnetic north?
I use a plain compass with no declination adjustment.
Not a bad question, but the reason is that declination changes over time for the same region, so you’d have to print new maps every few years to correct for the change.
When I learned map & compass, few compasses had declination adjustment. The Silva Ranger may have been the only affordable one, and $70 was pretty expensive at the time.
The first step was to mark up the map with equally spaced lines oriented to magnetic north (Boy Scout Handbook, 1965, page 135).
Yes, declination changes, but I don’t exactly navigate to within 0.5º, so not a big deal.
One of mine does (a big fancy mirrored one), but I live very close to the zero line and get by with a smaller non-adjustable one. It’s a small orange “hunters compass” that has mirror sighting, is light weight and floats as well as having the usual fluid-damped needle and adjustable dial.
My navigation tends to be point to point using landmarks, though occasionally I’ve had to use triangulation or bearing/feature (back shoot and hit the path or river you’re on) to find my way.
I use a Brunton 40B Adventure Racing Compass primarily for SAR because it has the map grid tools built into it. It has a declination adjustment, but since I travel around the state I just leave it on zero and mentally make the adjustment.
I have a Brunton Eclipse, has declination adjustment. Never used that adjustment. To easy to forget it and screw things up when called to different locations. Really, nowadays, I use my GPS for navigation and the compass is a backup tool mostly, or backup of the backup GPS…but it still is in my gear that makes it out to the field.
I’ve got a low end Silva of some sort. No declination adjustment. I actually use a label maker that I label with the location and adjustment, then trim to a sharp point on the one end and stick that to the compass so it points to the offset. I do most of my hiking around here, if I go on a special trip I just change it. When I come back I make a new label with any adjustments to the declination needed.
Yes I do. I use a suunto mc-2. I also have a suunto a-10 which does not have an adjustable declination setting. I think it is important to know how to use a compass that does not do the thinking for you. That being said, I much prefer the mc-2 both for the declination adjustment, as well as the sighting mirror.
I use my original silva type 15 ranger .. made in sweden … i bought over 30 years ago. still works great. still have the small tool that changes the declination via a tiny screw set in the bevel. have looked at newer/lighter compasses but not convinced saving a couple ounces is worth losing potential durability and accuracy.
In the Whites where we have 17 degrees westernly declination it is key to properly adjust for it during off trail and above treeline whiteout travel. It is a common topic of confusion among my students but with a bit of practice it becomes quite simple. Some people like RALS (Right Add Left Subtract)… but I have my own ways of remembering. Oh, back to the question, Yes, my compass has adjustable declination but I prefer to to use it, it can introduce errors in navigation elsewhere. I prefer to simply adjust when needed, which is only twice, map to compass or compass to map… much of what we do navigating does not require adjustment, so no need for a somewhat permanently adjusted compass IMO. Here’s a quick write up of my last Land Navigation workshop: https://davidlottmann.wordpress.com/2012/10/28/land-navigation-course-10-27-2012/
Yes, I use the declination adjustment on my suunto m2.
For years I had no declination adjustment, then I went and lost my compass. It was only then that I realized such things were made! Set once and forget. Brilliant!
I have a Silva Voyager 8010 adjustable declination Compass for Australia and sadly a non-adjustable declination model (Silva Polaris) for the UK.
I’m on the Challenge again in 2013 :)
Question?? I have a Suunto Vector watch with a compass feature. Does the bearing indicated on the watch face include compensation for declination? Thanks.
No, but you can set it. Bet you’re glad I asked, huh?
Search on google for instructions.
I’d add that electronic compasses like that need frequent calibration since as the battery in the watch dies it effects the local polarity. I wouldn’t rely on an electronic watch compass for serious navigating, but it is a handy back-up if you forgot your real compass.
Yes, a silva Mod 15. Never sure if i like the mirror or not.
Decided to post a comment as I thought this might be new to you…
The compass is a clip on silva model 19NL (very cheap, i think intended for orienteering). The Clippy card is from Navigation for Walkers – https://www.amazon.co.uk/Navigation-Walkers-Definitive-Guide-Reading/dp/1904207626
This stays on inside the map case, you match up the markings to set the declination. Obviously you still need a proper compass if you want to take an accurate bearing, but it’s handy when you just need a quick check of the map.
I have a wicked cool compass (Silva Ranger) that has all sorts of gadgets, including that declination adjusting thing. I rarely use it, but it is somewhere in my pack.
No. I just use a cheap $10 compass. It never bothered me. I think the theory is a lot more challenging than actually using magnetic declination.
If a compass can not be adjusted for declinatin I will not carry it.
I have a Silva Ranger and really like it.
I’m REALLY lazy, so I generally eyeball the difference. Of course, I’m usually hiking in more open terrain and mostly on trails. If I’m in the deep dark woods and a degree or two is critical, I’ll set it.
I did have a situation last week when hiking in Oklahoma where I lost the poorly marked trail, however, in that case, I used the GPS on my phone along with the topographic software I’d loaded to figure out which hills the trail was supposed to be on and bushwhacked toward the saddles and ridges in question. A whole bunch of that hike was off trail but I followed the topo map to intersect the area where the trail maintenance picked up.
I met other hikers in the area who were floundering in the woods as well, so I kinda, sorta volunteered to the Park Naturalist to help mark the trail better. I’ll have to go back up there in a couple months and be true to my word–any excuse to go backpacking!
Suunto M3, been using them for years, and always set the declination correctly.
I’ve been teaching land navigation for a long time, and without question the one topic that consistently confuses beginners more than any other is the adding / subtracting declination.
In a short weekend class, there are so many other better things to give your attention to than that.
If you’re too cheap to spend $30 or $40 on a good compass, just get a simple baseplate model and draw the declination in with a sharpie pen. Then, align your magnetic needle to that rather than the orienting arrow.
Thanks for the Suunto M3 suggestion. Just what I was looking for! I don’t think I need a sighting mirror but wanted adjustable declination and keep around $30. I stopped at REI yesterday to compare Suunto and Bunton Truarc and I thought Suunto needles were night and day faster and more steady.
The Truarc is also a little less intuitive to adjust – actually the instructions are appallingly bad. You might also find this review of the M3 worthwhile reading.
I own two Suunto Mc2’s, a Brunton tru-arc, and a 50 year old silva boy scout compass. I use the adjustable ones when working with map & compass in the field, and carry the non adjustable compass as a back up.