Brunton 7DNL Compass Review

[Addie Bedford]

Companion forum thread to:

Brunton 7DNL Compass Review

[Bill B]

Roger,
Great review. I have also found over time that a sighting compass is of little use to me. It souns like from your review that the declination is adjustable, seperate from the rotating bezel, but Brunton's description of the compass says,"fixed declination scale". can you explain?

[Nicholas Luhr]

I can scarcely imagine a compass without a sigting mirror to be useful. If you try to perform landfall navigation with a plate-only compass like this, you will have larger average error on each iteration and by the time you have gone far enough distance wise, your total error will have been multiplied many times.

A compass like this is for somebody who doesn't know how to use a compass and is just checking general orientation, not actually using it to navigate with accuracy – In other words, great for somebody who will stay on a trail at all times and has no need to accurately triangulate their position in complex terrain and has no need to follow a bearing with close accuracy for miles of terrain where tree canopy prevents any triangulation.

[Jonathan Shefftz]

Okay, so good to know that the Brunton cheapo light compass is a bit better than the comparable ~$10 competition. I sometimes carry one of these as backup, or when I don't expect to be doing any navigation.
But when I do expect to be doing significant navigation, often following a bearing from the GoTo function of my GPS, I use a more full-featured compass.
So what explains this part of the review? —
"The heavy end is the domain of the mirror and other sighting compasses. I am sure they have a use somewhere, but I find them rather clumsy and impractical. In fact, some of them seem downright awkward or worse. I also find that I can get just as good a bearing from a simpler compass as one of these, so they are just excess weight for me. Perhaps if I was trying to locate myself on a broad flat plain by sighting on distant sharp peaks they might have a slight advantage, but 'flat plains and distant peaks' doesn't describe any of the country I walk in."
— In short, I'm with Nicholas here. Do these models weigh more? Yes. Bulkier? Yes. But clumsy, impractical, awkward — how so? The declination is easy & precise to adjust in advance, so one less thing to worry about. The needle balances very well. Sighting through the slot in the bottom of the mirror is very easy.

[Chris Townsend]

I'm not going to knock mirror/sighting compasses but it's false to say they are needed for complex navigation. Orienteers don't use them and their navigation needs to be precise. I've played with sighting compasses but use an ordinary base plate one most of the time and I do a great deal of off-trail hiking in mist on featureless terrain in the Scottish Highlands. I've also taught navigation for ski touring with base-plate compasses. In fact the compass I've used most is the Silva 7 – the same as the one Roger reviews other than the name.

[Rog Tallbloke]

I use a longer baseplate Silva 4/54 model. Not because it has a long baseplate, but because it has tritium markings which help when night walking on a bearing.

There is a guy on UK ebay selling ex army ones ridiculously cheap. item 370372471426

[Geoff Webb]

The need for compass accuracy is a relative thing. Most of my time in the backcountry is spent in places where terrain association is more important than having a super accurate compass. Usually the lake, peak, or col, I'm looking for is large enough that I can find it with the Silva 7 I carry.

I don't usually find myself in trackless desert or jungles where terrain association won't help you. I also don't usually have to find caches of equipment or food. Mirrored sighting compasses are what are needed for these types of activities.

Compasses like Roger reviewed may not be the best for all situations, but I wouldn't say they are only for clueless noobs who never leave the trail either.

As with most things, you need to choose the right gear for the stuff you do, not what some one says you need. Different strokes for different folks.

[Nicholas Luhr]

The problem with not having a mirror is you are less capable of taking accurate readings. When you use a non-mirror compass, the only way sight a bearing is to hold it up in front of you and view along the straight edged baseplate… but holding it in front of your eye so this is possible means you cannot see the needle to ensure it is still boxed in the meridian lines and also that it's still free-floating and not just being dragged by friction because your hand isn't perfectly level. I'd be surprised if you can level the compass, box the needle, and then bring it up to view without changing it less than a degree or so. The mirror lets you watch the needle WHILE sighting AND gives you a rifle sight through which you can sight a specific point.

It's one thing to orienteer (determine your position) you can put the compass on a flat surface, move it around on the map, get on your hands and knees to sight along the baseplate for triangulation, etc. I think anybody could do this with a simple baseplate type compass and some arithmetic (to account for declination). Navigation is the process of actually going somewhere and it's a whole different ballgame. It requires you to take readings dynamically and frequently. If you can't rapidly sight a bearing, you won't do it enough and you'll get lost OR you'll do it but will take twice as long to get anywhere. If you can't accurately sight on objects both near and far, your error will continue to compound itself and you'll be way off target, meaning you need to use a very large intentional error to avoid missing your target. Very large intentional error may mean you take far more time and travel much further because you couldn't head more directly to your target.

I can travel over a mile through dense hilly/rocky/forest and streams and come out with an accuracy of less than a half degree error from my starting point because I am able to sight with tight accuracy on objects that are relatively close to me (distant objects being blocked from view) and continue following my bearing with accuracy and precision. That is within 46ft over a mile of difficult travel (clambering over rocks, downed trees, around brushpiles, through streams, etc. How close can you get without a sighting mirror? On open ground with no trees (scottish higlands?) you can sight on something much further, thus reducing the number of chances for error, and get away with it, but then again, in terrain like that, you can see your destination from a mile away so it wouldn't matter. I totally understand what you mean, Geoff… many places the terrain is distinct enough that you don't need anything other than basic terrain knowledge to know where you are. The point is, when you NEED a compass to navigate, you need more than a baseplate.

Also, I don't see an inclinometer on this compass… Knowing the slope angle is a major factor in orienteering (when combined with altitude and/or aspect, you could narrow your location to just a couple possibilities). Seems a crime to omit the 2grams an inclinometer would cost when it provides a relatively useful bit of information.

So in the fervor that is lightweight backpacking, it seems to me efficiency is often overlooked. If you omit the extra three ounces that a sighting mirror costs but then have to travel greater distances (because of intentional error or because you get lost) with less certainty, what's the point? Masochism?

[Ethan A.]

Which are the lightest reliable mirror sighting compasses?

[Nicholas Luhr]

The Suunto MC-2 series are around 2.6oz but barely any of them are over 3oz.

There is a graphite-based Silva that is 1.2oz but the opaque base reduces its usefulness on a topographic map and it has no clinometer, and no declination so you're forced to do the math in the field, potentially under duress.

There is also the small Brunton 26DNL-CL which has an opaque base and no declination but does have a clinometer, also 1.2oz.

Personally I just like my Silva Ranger CL. The Brunton 15TDCL is also a gold standard, both of these are 3oz.

[Rog Tallbloke]

I have a very nice Suunto military prismatic with tritium markings. Only trouble is, it has some obscure number of degrees around it which don't relate readily to 360. What's up with that?

[Tohru Ohnuki]

Military compasses tend to be in mils:
http://en.wikipedia.org/wiki/Angular_mil

It's convenient for gauging distances as one mil is one meter wide at one kilometer.

[Rog Tallbloke]

A neat and accurate reply. Thanks a lot! I'll start carrying the heavy little 3oz beast around and guaging distances for fun. :-)

[Chris Townsend]

Nicholas, I can navigate just as accurately with a base plate compass. It's not difficult. And I never hold the base up to my eye. Also, orienteering is about navigating in woods and finding tiny markers – it requires good skills and accuracy. And as it's competitive orienteers want to find the most direct route. You are confusing it with orienting the map and finding your position.

And in the Scottish Highlands I am often navigating in thick cloud where visibility is down to fifty feet or less. In winter I often navigate in white-outs too.

I've used a Silva 7 compass for around 30 years and never had a problem with it in any type of terrain or visibility. I've never needed a sighting compass.

[Tohru Ohnuki]

I like this model:
http://www.amazon.com/Brunton-Compact-Mirrored-Compass-Luminous/dp/B000093ILN

It's also nice in that you can clip it onto your pack strap and it will hold it level.

[Bob Gross]

I agree with Chris, and I have used dozens of different compasses in my life. I think navigating by compass in the Scottish Highlands in thick cloud would be a great challenge (I think that is what the Scotsman calls a fair day). Many of us do more navigation around timberline in the Sierra Nevada, and we can go for days and days without ever picking up a compass at all. Most of the time, I don't bother to carry a compass with declination adjustment, and I just do the math in my head.

–B.G.–

[Roger Caffin]

Hi Bill

> "fixed declination scale"
Yeah, well, marketing wrote the blurb …
I think what it means is that there is a fixed set of lines on the base plate, and you rotate the bezel over that to set the declination. Rather standard on any base-plate compass, actually!

Cheers

[Roger Caffin]

Hi Geoff

> I wouldn't say they are only for clueless noobs who never leave the trail either.
Actually, what we often find is that the more experienced the walker, the smaller and lighter the compass.

For myself, I actually navigate off the sun most of the time. I check once with the compass to see roughly where the sun should be, and then go from there. This works (but see next posting).

Cheers

[Chris Townsend]

"I actually navigate off the sun most of the time"

Roger, how lucky you are! I often navigate off the wind.

[Roger Caffin]

Hi Nicholas, and others

> The problem with not having a mirror is you are less capable of taking accurate
> readings. When you use a non-mirror compass, the only way sight a bearing is to
> hold it up in front of you and view along the straight edged baseplate… but
> holding it in front of your eye so this is possible means you cannot see the needle
> to ensure it is still boxed in the meridian lines and also that it's still
> free-floating and not just being dragged by friction because your hand isn't
> perfectly level.

I understand what you (and others) are saying, but there is an assumption here which is not true. You do NOT have to sight along a compass edge to take a bearing **in order to navigate**. How many of us navigate is different, and I will spell out how. (I am assuming off-trail travel here.)

You are travelling along a ridge (or a valley). There is a fork in the ridge or creek. Which one do you take? You don't need sightings to determine that. Or you want to check which side creek you have reached – is the river going north or north-west just here, and the side creek is going in what direction? Side of range – similar comments.

What we are doing here is using the compass AND THE MAP for our navigation. It's no use knowing to 0.1 degrees where True North is if you don't have a map to be able to decide where you want to go. (Alice in Wonderland) Once you combine map AND compass you can navigate using the terrain, matching it against a mental model you have built from the topo map. This can be done while travelling at high speed too.

Yes, there are two problems with the above.
* What if you are in Scotland and there is no sun? Happens. :-)
* What if all you have is a sketch map, without contours? More tricky, but highly accurate compass bearings are unlikely to be much use in that case either.

How do I use a map and compass to locate myself? I rarely take bearings. What I do, and I think I said this in the article, is I use the compass to **align the map** within a degree or two. That is done with the compass lying on the map. The last picture in the article shows me doing this. Then I look around me and use the surrounding terrain to work out where I am. But not just distant peaks (which we don't have anyhow), but also the saddles, spurs, gullies, and even the slope of the land where I am standing.

> I can travel over a mile through dense hilly/rocky/forest and streams and come out
> with an accuracy of less than a half degree error from my starting point
For sure, and we normally do that holding a baseplate compass in one hand while we travel, without taking bearings. In thick scrub. Much faster travelling that way, but it does take practice. Yes, we can and do match that sort of deadfall, regularly. And yes, that is in the Australian bush, where you can't see more than one or two hundred yards at a time anyhow. Thick scrub.

> Seems a crime to omit the 2grams an inclinometer
I can tell from a topo map *roughly* how steep the terrain should be, and I can estimate to within 5 degrees what the local slope is. But topo maps are NEVER that good, and relying on an accurate measurement of slope to determine position is not something I would ever want to have to rely on. Some of our local topos – if there are two 20 meter contour lines close together we know it really means a cliff!
Altitude – yeah, I do carry an altimeter. Useful in some cases.

> If you omit the extra three ounces that a sighting mirror costs but then have to
> travel greater distances (because of intentional error or because you get lost)
> with less certainty
There are two false assumptions here.
* The first is that not having a sighting mirror will cause you to travel greater distance because you have got lost. I dispute that – it doesn't happen to us.
* The second is that having a sighting mirror will get you to your destination dead-on every time. I question that too!

Bottom line: you need compass AND map to navigate.

Cheers

[Roger Caffin]

Hi Chris

> Roger, how lucky you are! I often navigate off the wind.
I was thinking of you when I wrote that!

Yes, I have been walking and climbing in Scotland too. Ice climbing around Glen Coe. I understand …

Cheers

[Dale Crandall]

In this neck of the wilds (North Cascades), nobody gets to walk in a straight line very far. The two purposes of a compass here are to generally orient yourself in the topography, and then to generally follow the chosen topography in the right directions and elevations. The topography always dictates the route, whether on trails or off. I used sighting compasses for a long time for orienting myself, but found I didn't need that much accuracy for that purpose, and found I was tempted to spend too much time looking through the compass instead of walking with awareness of which drainage I was in. Now I use a Suunto A30 (similar to this reviewed Brunton but with a magnifier) on a color photocopy of a portion of a detailed topo map. If you don't have recognizable topography to work with, use a mirrored/sighting compass.

[Bob Gross]

"Bottom line: you need compass AND map to navigate."

…and you need the skills to put them together.

The modern alternative is GPS. Unfortunately, too many backcountry travelers get totally dependent on GPS, and they let their traditional map and compass skills go bad. Then, when the GPS batteries fail, or when there is a GPS*Blunder*, you can get in an awkward position.

I navigate 90% of the time purely by map and sun angle. Once in a great while, I will pull out a compass to confirm what I already think about bearing. Often I use GPS to confirm what I already think about position.

–B.G.–

[Roger Caffin]

Bob wrote:

> I navigate 90% of the time purely by map and sun angle. Once in a great while,
> I will pull out a compass to confirm what I already think about bearing.

+1

Cheers

[eric levine]

If you want the simplicity of a baseplate w/ the ability to sight 1/2 deg. using no skill, give the Brunton (Silva) combi 54 a look. It's a large baseplate with a real sighting compass built in. Weight at 1.3 oz w/o lanyard is not too bad, but the same cannot be said of its price.

Also, no declination adjustment is possible, but I've never found such an adjustment needed. One can always draw in some mag. north lines on the maps; at say, half mile intervals. Or just add/subtract the declination number. That "west best — east least" thing I've never found usefull. Does it mean field to map or map to field? For those of us in the US west, "first man adam" (field to map add) is gives what you need.

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