Brunton 7DNL compass, courtesy Brunton.
There are many different sorts of compasses, ranging from tiny button things to great hulking surveyor/military things. In between we have the typical baseplate compasses.
One problem with the tiny compasses is that many of them are prone to sticking if you don't have them precisely level. I've tried quite a few and never been really confident about relying on them, even though they are so ultralight. Another problem with them is that they don't allow you to get a very accurate bearing. In fact, many of them don't have much more than the four (or eight) cardinal points marked on them.
The obvious problem with the big surveyor/military ones is weight. I have an Australian Army prismatic compass which weighs half a ton: it is made from solid brass. It (truthfully) comes from World War II. To be sure, I can read it (and trust it) to half a degree or better, but I don't need that accuracy in the field. I did find it useful for surveying my farm though.
In between we have the broad category of baseplate compasses. These have a disk-shaped liquid-filled module mounted on some sort of flat baseplate and come in a range of weights and sizes. 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.
That leaves us with the simple baseplate units. Some of these have big baseplates, and others have little baseplates. The argument for the bigger baseplate is greater accuracy, except that I have never found that necessary or even useful, even for tricky navigation. The bigger baseplates also sometimes have a magnifying glass embedded in them: I haven't found that to be a real lot of use either.
Brunton 9030 compass, courtesy Brunton.
In fact, up until recently my favourite 'baseplate' compass did not even have an extended baseplate per se. It was very much like the Brunton 9030 shown here: just the round compass module, rotating inside an outer ring for declination adjustment. Yes, there is a 'baseplate' attached to the black ring under the rotating module, with the logo and arrow on it. I bought mine in France after I (ahem) lost my previous compass in the mountains. I think mine was made in China: it was fairly cheap. I have shown the Brunton 9030 here to illustrate what I mean by a compass without an extended baseplate. But after many long trips in the mountains over many years, my Chinese one started to lose the damping fluid inside the module, and it was time for a new one.
I looked at a range of baseplate compasses. Many of them had long plates with corners. The length can be a bit inconvenient at times, since I usually carry my compass hanging around my neck (a compass is of no use if you can't get at it easily). The corners on the long baseplates can dig into my chest. This model 7DNL is the lightest and smallest baseplate in the Brunton range, at only 25.5 g (0.91 oz).
The rotation of the compass module on the baseplate to set the local declination is really very smooth, but there is just enough friction to keep the declination set. The red ring used to rotate the module is a smooth and tactile polymer band: no sharp corners. It handles nicely.
The markings around the edge have been hot-stamped into the plastic: they are not just painted on the surface. This means it should be a long while before they wear off. One could wish the lines were a shade narrower, but really they don't matter that much. I normally align the compass with the needle anyhow by rotating the whole unit. This automatically corrects for the local declination.
North is THERE??
One thing I did notice was that the needle looks a bit tilted when the compass is flat on the table. The white S-seeking end of the needle points slightly downwards. That means I have to tilt the compass slightly (about 5 degrees) to be absolutely sure the needle is able to swing freely. This isn't hard to do and becomes automatic.
The need for this tilt is hardly surprising, as the magnetic field around where I live (Sydney, Australia) is actually tilted some 64 degrees downwards. That's really pretty savage, so a tilt of the compass needle of 5 degrees is rather small. Actually, all our compasses need a similar amount of tilt to swing most freely, so there is nothing special about this one. Yes, in Europe the tilt goes the other way, as expected.
Brunton supplies a soft red loop of cord which can be used as a neck loop for hanging the compass around your neck. It's a very good idea, and that's how I carry my compass. However, an hour after hanging the compass around my neck, I found the cord was really twisted up something awful. I unraveled all the twists and continued. An hour later, the twists were back: this happened several times in one day. I simply do not know what was the matter with the string, but it was too much for me and I replaced it with my own.
Specifications and Features
|Manufacturer||Silva Production (looks identical to Silva Field 7)|
|Country of origin||Sweden|
|Needle pivot||Sapphire jewel bearing|
|Graduations||2 degrees, hot stamped|
|Measurement Scales||Metric and Imperial|
|Size||85 x 54 x 9.5 mm (3.4 x 2.1 x 0.37 in)|
|Weight (claimed)||25.5 g (0.9 oz)|
|Weight (measured)||27 g (0.95 oz) with supplied neck cord|
|MSRP||US$15, but retail US$10 - 12 has been seen|
- Easy to use
- Bold markings
- Slightly finer definition on the printing
- Better quality string