Take a few moments to jump in and learn some compass navigations tips and tricks and check out two prominent baseplate style compasses from Brunton and Suunto! Breaking from tradition, we’ve got a pic-heavy article to help with the learning process, but be ready for a detail overload!
For many reasons, beyond the intentions of this article, I am a huge advocate of the baseplate style compass. Pictured is the Sunnto M-3G with global needle.
When you decide to jump from a baseplate compass into a sighting compass, there are no two bigger names that the Suunto MC-2G and the Brunton 8099 Eclipse (The Silva Ranger is also an extremely popular choice. However, it is nearly identical in form, functions and looks to the Suunto that an additional comparison does not really make sense). While these are both top end sighting compasses from two very reputable manufacturers, they vary greatly in style. Which one fits your style? We are about to find out : )
Both compasses carry a list of features you would expect to see on this type of compass. Rather than list them out in boring detail, I would rather point them out while showing how each compass operates. Before I get into the real world operation of each, I want to take a moment to talk about the needles in each.
The Brunton utilizes a disc magnet, which are notorious for their speed. The reason is that the magnet is close to the center, which is the axis of rotation for the magnet. It is easy to visualize why it will dampen quicker if you compare that to the traditional compass needle, having the magnet at the end of a long stick, far away from center. The result is that needle function is both fast and smooth.
The Suunto utilized a global needle. Compass needles are balanced for either northern or southern hemisphere use. In the northern hemisphere, the earth’s magnetic pole wants to tend to pull the north needle to the ground. In order to compensate for this, the south needle is generally weighted (although I have seen mass removed from the north needle).
The idea behind Suunto’s global needle is to have the magnetic (center) spin freely of the actual compass needle. This allows the magnet to tilt however it needs to, and have the needle stay level. It is actually very slick, and reminds me of a gyroscope.
While this is all well and good if you are a world traveler, the global needle also has two amazing benefits for the non-world traveler. First, the dampening is crazy fast! For the same reason the disc compass is generally fast, the small, center magnet in this needle dampens faster than any other baseplate or sighting compass I have seen. Second, since the magnet and needle operate semi-separately it allows the user to get very sloppy with their level hold and still get accurate readings. While I don’t advocate sloppy technique, sometimes it is nice to have every advantage you can get a hold of : )
Good enough. Let’s get using them. Let’s take a non-sighted bearing with each.
Easy enough. Hold the compass level at your belly (so you can look directly over top of it), point to an object, and box the needle. While the Suunto does not have a traditional “doghouse” lining things up is not really an issue.
Read your bearing.
Notice the Suunto has the very standard 2 degree increments. This allows you to very easily split the marks, getting a very accurate 1 degree resolution. You can even split that further and approximately ½ of a degree without much issue. Which is more than likely going to be beyond the capability of my users.
Need to know how to get back? Conveniently, Suunto provided another index line for reading the back bearing, among other things.
Same drill. But first, it is important to note that the Brunton actually has two covers. The first, smaller one allows you to do non-sighted and sighted bearings.
The second cover gives you access to the clear baseplate, meridian lines and scales for working with a map. We will do that later.
The small cover is a neat idea. One of the drawbacks of a sighting compass is having to open and close it all the time just to use it. The small cover is quick an easy. Okay….on with the exercise.
Hold the compass level at your belly, point to an object, and……and……wait a minute…..where did the doghouse go? A lot of Brunton’s compasses are using the circle over circle style of alignment.
Very neat and fast concept. But, we will see what we think of it as we use it more.
Read the bearing.
First thing to note here is that the bearing is read on the user side of the capsule. Nothing big, but it is just different that most compasses, where it is read on the farther end of the capsule. There are three very neat features here. First, are the 1 degree increments on the bezel. That is the most resolution you are going to be able to buy in this style compass. I like having it. Second, is that there is a magnification bubble to help you read the bearing.
Third, is multiple bearing scales. Both the bearing and back bearing can be read at the same time, in the same location, just by looking at the different scales.
This is also my first nit pick on the Brunton. The back bearing scale seems to be hidden kind of far up in the housing. To read it you almost have to tilt the compass backward a little to see in there. That kind of goes against the most basic of rules; keep your compass level. I guess at that point your circles have been aligned, bezel has been rotated, and now you are not going to move it. So, tilting the compass to read the back bearing is no biggie I guess.
That is a lot of talking for just a little bit of work. But trust me, it gets much better. So keep reading.
This is where it really gets interesting. We are going to do sighted bearings. The technique is similar on both. The compass now moves up from the belly position closer to your face. How you do the alignment of each, I will detail.
The Suunto is very standard for a sighting compass. You use the notch in the cover to sight on a distant object.
Next, you use the mirror to look down upon the capsule, doghouse and north arrow to make everything line up and read your bearing. It is important to note that the mirror has a line that is meant to line up with the forward and rearward index line. This eliminates one type of parallax error.
The mirror has no “pre-set” positions like a lot of compasses. You just adjust the angle to make things work for you.
This is where the subject matter gets a bit ugly. By lining up the mirror line with the forward index line and rearward index line, we eliminated one type of parallax. But, there is another and there is no way around discussing it.
When holding the compass out our belly, we were able to look directly over the compass. Now, we are holding it at eye level, with an angled mirror, and doghouse at yet another angle. Alignment gets a bit more difficult. So, let’s just discuss the worst case scenario…..the doghouse at a 90 degree angle to the sighting mirror plane.
The problem and solution are both fairly easy with the Suunto. Because of the angles involved we can not physically see when the needle is directly over top of the doghouse. Yet, because the needle is a line, and we have the doghouse lines, we just need to make everything parallel.
Without moving the compass, we verify accuracy by looking from above.
Problem solved. Let’s move on to the Brunton.
Again, we have a sighting notch for sighting on a distant object.
Again, we have both a line on the sighting mirror and a line opposite the capsule for proper alignment.
It is also important to note that Brunton claims the sighting mirror to have “three pre-measured angles – 45, 90 and 120.” Those are the exact words from the manual. I am assuming they mean detents for the sighting mirror to stop at.
Those pre-sets are quite laid back. In the 45 degree setting, I measure about 1/2 inch of movment in the mirror. At the 90 degree setting, it seems to just click to let you know you have reached that setting, yet it moves freely all the way open to the 120 degree setting. You then have to get it past the 120 detent to open it all the way for map work. In generally, I am saying that it feels very sloppy. We will see if it actually means anything in use, or if I am just being picky.
Now, the worst case parallax problem, 90 degrees. This is where my real heartburn with the Brunton begins. With the Suunto, we had a bunch of lines to just make parallel, and we solved this issue. With Brunton’s circle over circle, it is a different story.
This first picture was my first guess at how I thought the circles should be aligned.
Viewed from above, you can see that I was wrong.
The error? Five degrees! That is way more than significant in my book. Especially on a compass that has a selling feature of 1 degree graduations. But, I like this compass, so I am not ready to give up yet.
The bottom line is that I came up with a way to make this work. I am not extremely happy about it, and it leaves the possibility for error in use still. But, it seems accurate and repeatable. I played with many, many different methods, and I am not going to bore you with all the stuff that did not work. Instead, here is what I found that did work. You may find another way, but here is what I did.
The sighting mirror needs to be as low as possible to the compass. The smaller distance lessens the parallax. Yet, when it is too low you can not see the line opposite the capsule to make sure alignment is correct. So, I put it in the lowest possible position to barely be able to see some of that line. This position is still too high for alignment to be correct.
Then, with the slop in the sighting mirror detent (discussed earlier) I flop it down to its lowest spot in that range. Note, I can no longer see the alignment line.
In this low setting you can achieve and accurate alignment that is correct when viewed from above.
Now, in order to make sure I didn’t move anything, I keep my thumb on the sighting mirror, push it up to check alignment of sighting lines, let if fall to the lowest position to check alignment of north and orienteering circles, and bounce back and forth a few times to double check everything. I am not extremely happy about that, but at least it is a method that works. I think many owners of this compass do not even realize that there is a potentially HUGE error with this compass. If you own one, play with it!
Let’s move on to taking a bearing from a map. The reason I am such a huge advocate of the baseplate compass is the ability to take a bearing from a map (or transfer one to a map) using only the protractor feature of the compass. The angle between your direction of travel and the north/south lines do not change if you turn the map over, upside down, or dance in a circle. That makes work in the field much simpler. If you use the “orient the map method” first you orient the map, then you have to hold it STILL while you spin a compass around on it. Keeping accuracy in mind, I can never do it. I always feel like the map has moved. Add on top of that bugs, sweat, rain and fatigue, and no thanks! I will stick with the method described below. I have tried small clipboards, but even find those too cumbersome. Not to mention that the metal clips make the upper half of the board unusable because of its effects on the bearings.
It also does not depend on what the magnetic needle is doing, because you are simply measuring angle. To me, that is very important if you are trying to route plan on a table, which more than likely has metal in it, and can mess your bearings without you ever knowing.
Try setting your compass on a table or counter top. Move it around and watch what happens to the needle. If you use the “orient the map” method to get bearings, it will be effected by that needle movement.
Okay, let’s stop talking and do this.
We have our map. We know where we are and where we want to go.
I typically don’t actually draw the line, but I did to illustrate the technique. Now, line up the compass edge with the line.
Rotate capsule so that the doghouse is going in the northern direction, and get exact alignment when the meridian lines in the capsule line up with north/south meridian lines on the map.
Done. Read the bearing at the index line.
Keep in mind that I am leaving declination out of the discussion for now. There are two extremely simple ways for dealing with it, but is beyond the intention of this article.
In order to get to your end point, you now hold the compass at belly level, box the needle in the doghouse, and walk your bearing (picking landmarks of course).
An interesting side note is that military style lensatic compasses can not even use this method because of the lack of the protractor. I carried and used one for years and even though I love the compass, and the construction of them, I abandoned them because of the simplicity of this method. A separate protractor can be carried, but I figured why need one more thing! : )
Because of the reasons mentioned above on “orienting the map” I am going to use the exact same methodology with the Brunton for doing the bearing. However, there is something significant to note; Brunton’s primary intention seems to be for you to orient the map to get your bearing. Because of this, they have left meridian lines out of the capsule.
Instead, they put them on the outer ring (which is not transparent). We will see what the means in use.
Same drill. Line the edge of the compass up along direction of intended travel, get the orienteering circle pointing in a northern direction, and do the exact alignment with the meridian lines.
Done. Read the bearing at the index line.
This is yet another nit pick on the Brunton. Why don’t you just put lines in the capsule? By the lines being on the outside of the capsule, and in a non-clear area, you are forced to use more judgment in the alignment. Guessing seems to go against the idea of a super accurate compass.
At first, I thought it was not as big of an issue as I was making it because the orienteering circle has a line, which is all the way across the capsule, and inside. I figured this could be used to tweak exact alignment. However, if you using the declination adjustable feature of this compass, that will not work because that line will no longer be north and south. It was a nice thought.
If it seems like I am being a stickler on this subject, just try to take bearings off the map some time and tell me what you think of it for precise navigation.
Let’s move on to adjustable declination. This is one of the EASY methods for dealing with declination, and I use it often. Both compasses have it, and both work very well.
The Suunto has an adjustment screw on the back, and a supplied tool on the lanyard.
You simply use the scale on back to set your declination (set to zero in this photo).
I adjusted the declination, and you can see it basically skews the doghouse with respect to the meridian lines.
This is my first nitpick on the Suunto. Suunto decided to not use a traditional looking doghouse, and instead just has two luminous marks. With it not adjusted declination, it is no big deal because you have all the meridian lines in there as well. With it adjusted for declination, you just don’t have as much “stuff” to line up to as a traditional doghouse. It in no way has effected performance or use, but is more of a “I wish they would have done it better” type of complaint.
The Brunton is adjustable too, and even easier! Y ou simply hold the outer ring of the capsule with one hand, and turn the inner capsule with your other hand. There is also a scale on back for the adjustment (set to zero in this photo).
I then adjusted it for declination.
Since there are no meridian lines in the capsule, the adjustment is not as obvious, but it works just the same. You have to look at the relationship between the orienteering arrow and the meridian in the outer ring of the capsule, to see the new “skewed” relationship.
Let’s move on to night time navigation.
First, as a backpacker and a hiker, I am obligated to say that you should do neither at night. It is a dangerous activity. However, it is inevitable that continuing on the trail is preferable to bivouacking.
Also, as an avid hunter, night time travel is almost a must. Being in the blind before sun up is common, and not leaving until darkness is just as common. Therefore, I think it is important to be able to use your navigation tools in the darkness. Let’s see how each compass does this task.
Most compasses require a shot of light to activate the charge the glow thingies. And yes, glow thingies is a technical term! Tritium compasses are available, but not in either of these two models. I am not a huge fan of tritium on compasses, but that is a whole different discussion.
To be fair to each of these compasses, I used a surefire P60 and illuminated the compass in dark conditions for 10 seconds and took photos to see to see the result.
The Suunto rocks in this regard. Above and below the mirror there are glowing pins. Not just paint, but pins.
Both the forward and rearward index lines illuminate. The north arrow has illumination as well as the doghouse. Even better, the whole bezel illuminates. That is not so common in a baseplate compass, but it is awesome.
Bottom line, is that I would have no problem trying to navigate with this compass at night. In fact, it is probably one of the best that I have seen.
In this aspect, the Brunton did not fare so well. I guess I will just let the photo speak for itself.
No, this is not a joke. It really is ALL black! The Brunton has no luminous features. In fact, due to the silk screening of the north arrow, orienteering arrow and the black rubber baseplate cover, sighted bearing is even moderately low light conditions are almost impossible.
(Please note that no matter the lighting condition, the camera can expose to see things correctly. So, I had to underexpose a photo to simulate what the eye sees. It is not hard to imagine what I am trying to document).
I am not even talking really low light. I mean in your house, during the day, but with no lights on. I am quite disappointed in the usability of this compass under these conditions.
Removing the black baseplate cover (because it is black rubber) makes low light use easier, but for some reason not as easy to see as a normal needle/doghouse.
All right, let’s move on to a few items that are important, but not thought about as much.
First, is the scales and markings on the baseplate. The Brunton’s markings are simply screened on.
The problem with this is that if the paint rubs off just because of use, they are gone for good.
On the Suunto, there is obviously paint for the scales, but they are also etched into the plastic. Meaning that if the paint were to wear off during use, you could re-paint the etchings.
Next is DEET.
Ever since DEET melted its first watch, and took markings off its first compass, it has been taboo to get it near ANYTHING! However, I think manufacturers have become wise to this, and modifying their products accordingly. In order to test this, I used Jungle Juice, which is 100% DEET and selectively sprayed it on each compass baseplate markings. I am very happy to report that it had no effect on either compass. Still, I think you should do what you can to keep chemical and oils off your compass, but sometimes you just need to know what your stuff can do.
If anyone has read this far, you must really be a diehard compass geek, like me! For you, I will summarize my perceived strength and weakness for each compass.
Summary of strengths and weaknesses
– Global needle rocks
– 2 degree scale
– Etched and painted rulers
– Great illumination
– Declination adjustable
– Available in English or metric units (predominate scales)
– DEET resistant
– The doghouse could be more substantial than two luminous marks.
– 1 Degree scale (not very common)
– Magnifying bubble to read the scale
– Forward and backward bearings both on the dial
– Quick operation for bearings alone.
– Disc magnet
– Declination adjustable
– Multiple inclinometers
– DEET resistant
– The whole parallax things with circle over circle
– No meridian lines in capsule
– Sighting mirror slop
– Not good in low light and no illumination points
– Must remove base to use full function of the compass
– Scales are only painted, with no etching.
In summary, I do not intend to tell anyone which compass they should use. I simply picked the two expensive compasses, from two very popular manufacturers and compared them together. Their strengths and weaknesses are my opinion and based on how I use things. The bottom line is “use what works for you.” However, I hope I have brought at least some issues to light about each compass that you might not have otherwise considered. If that is true, then my time writing all this was well spent!