Ravenlore Bushcraft and Wilderness Skills. Transit Compass





		The Transit Compass

I have been looking for my ideal compass for a long time. I have owned many and been regularly disappointed when fluid filled ones develop air bubbles after getting cold or just being carried up a mountain. (As if that is unusual in my life.)

As such I was very interested to see a Brunton Transit Compass on a navigation workshop being run at the BCUK Bushmoot. It’s a dry compass and very accurate. As a geologists tool it is also designed to measure vertical angles and it was introduced to us as a rough and ready method of making an astronomical sighting. The only problem was the price.

So I was very interested to discover that there are some, much cheaper, Chinese copies available. (A quick internet search for DQY-1 or DQL-1 should yield results.)

So here is a quick review of the DQY-1 which is the non dampened version.

First impressions:

It's solidly made, all the joints are good with no sloppiness and in fact some are slightly stiff which means they should have some good wear time.

It's reassuringly heavy, it feels like it has a heft like the British Army Prismatic Marching compass, in fact I think it's slightly heavier.

The Southern end of the needle was a little high. This is due to the difference between the vertical angle of the Earths magnetic field between where the compass was made and where I am now. It was very easy to fix this by popping the O ring holding the glass and sliding the copper balancing wire a smidge towards the point to level it out. I like the fact that I can make this adjustment myself without having to send it halfway around the globe to get it done. It effectively means I can use it anywhere in the World with just a little tinkering.

The needle does hunt a little but seem to be very sensitive, it's sitting on my desk by my keyboard at the moment and I can see very slight movements as I hit different keys. I don't think I've ever seen such sensitivity in a liquid filled unit. If anything it does remind you that to take an accurate readings you should move away from substantial metal objects, including your knife in some cases.

There is a slight rattle from the needle, not uncommon in dry compasses, but when closed the needle is lifted against the glass by a button and so is silenced.

The button can also be depressed and released manually to help the needle to settle.

The long sight does not have a fixed vertical position when folded out from the body. I don't see any disadvantage to this arrangement. It's stiff enough to stay where you put it and if anything it gives you a wider angle of sighting positions.

One advantage that the Brunton has over this one is that the sighting line on the mirror also bisects the clear window, making alignment through the window slightly easier. Being used to peep sights I'm not sure that will bother me but it may be a consideration for some.

The bulls eye level seems accurate enough to level the compass and the long level on the clinometer is sensitive enough for degree measurements, possibly even half degree.

The screwdriver that is supplied is slightly too thick for the declination screw so I'll talk about that a bit later too.

So out in my workshop to fix the screwdriver, and a useful little detail came literally to light. there are luminous spots on the North side of the needle, the quadrants of the scale and the declination adjustment point.

With the screwdriver fixed, the declination screw moves the entire scale east or west. I only need 2° 40' W adjustment where I am, but the scale is marked for 30° either way. Incidentally, the small screwdriver head on the can opener of my Swiss Army Knife is thin enough to adjust this screw if needed.




	Close up of the declination scale, the main compass and clinometer scales, the levels and the balance on the South end of the needle.

On the Navigation workshop, it was mentioned that the main problem with using these for star sights was not being able to see the level in the dark. I had a hunch about that which does look like it will work.

The levels are filled with a fluorescent liquid as is common practice. So a small UV emitting mini LED torch, pointed into the compass makes the level very clear in the dark while not disrupting my night vision too much.

Although holding it feels a little awkward it does seem to address this issue quite well.


	A lever on the base of the compass is used to adjust the long level for clinometer readings.

Whilst fixing the screwdriver, I also checked the long clinometer level against my builders level, there seems to be about a quarter of a degree difference.

I am inclined to trust the clinometer as it's level seems the more sensitive of the two.

Either way, ¼° (or 15' or arc) is probably more accurate than I could reasonably expect to get from a hand held sighting with clinometer anyway.

Obviously this cannot compare with the accuracy of a good sextant and could amount to as much as 15 nautical miles inaccuracy in position, but as I am unlikely to be carrying a sextant with me in most instances it certainly out performs a Kamal or similar makeshift methods.

For map work it suffers the obvious disadvantage of not having a built in protractor like a baseplate compass. This can easily be remedied buy using a separate romer/protractor like the one shown above or even carrying a small baseplate compass as well, giving a useful back up too.

I should mention the case, it is reasonably sturdy and lined with thin closed cell foam. It is fit for purpose if a little ugly. I can also slide my romer into it which is handy but I can see myself making a better one at some point. For now this will certainly suffice.

The Brunton instructions suggest putting the top of the compass away from the press stud to protect the mirror from breakage. I am going to assume the same precaution is wise with this one too.

So next I set off up my local fell, I took some map bearings for features I knew I could see up there first, A mill chimney at about 3km and a church tower at just over 2km. I had figures from a car park and a trig point about a click apart so the distances vary slightly.

The car park bearings checked out exactly and to within -½°. The trig point bearings were also exact for the chimney and -½° for the church tower. Closer examination of the 25K map showed that the building has been overwritten with the church tower symbol. I used the centre of the square as my point but I think that may be incorrect on the ground. A small church length at 2 clicks is not too bad though I guess.

On the fell I also took some bearings from the same features, and a new one too, at a point in between my two reference points and used these to get a fix on my position.

The lines crossed within 2mm on the map, again my wandering church being the furthest out, and the other two being spot on a fence line almost exactly where I was standing.

This is by far the most accurate results I have achieved from such a test. I have never been given cause to actually doubt the accuracy of an OS map before.

All these bearings were taken using the long sights and with the compass resting on solid points. In two cases dry stone walls and a wooden gate post for the position fix.

Hand held bearings were made a little more difficult by the hunting of the needle, but not impossible. For hand held readings you can brace the compass at your waist and sight using the mirror as shown in the Brunton Instruction Manual.

Something I should have mentioned is that the instructions supplied with the compass are in Chinese, so unless that isn't a problem, you will want to check out the Brunton instructions anyway. The compass is more or less the same functionally.

As an experiment I took a star shot of Polaris from my back yard.

It wasn't easy, in fact I had to make a slight estimation as I couldn't really see the star and illuminate the level at the same time.

Although the UV led light worked well enough I don't think my eye was dark adapted enough.

The reading I got from the scale was 53° or maybe just a smidge under.

My latitude here according to the 25K OS map on Memory Map is 53°34'8"N So roughly 39 miles out on a first try. Make of that what you will.

I have an idea that might improve that, but I'll have to try that another night.

Pros:

Capable of taking very accurate bearings with a little care.

Capable of measuring vertical angles.

Allows magnetic declination (or variation) to be set on the dial.

Solidly built.

Not liquid filled meaning no more annoying air bubbles.

Inexpensive for an instrument of this quality.

Cons:

No built in protractor.

Requires a bit more knowledge and skill to use to it's full potential.

Not liquid filled requiring more time for the needle to settle.

Fairly heavy and a bit bulky.

So, in conclusion: Is it good value for money? Well for me it ticks all the right boxes. Most of the "Cons" listed above do not bother me much at all, although I do wonder about the damped version which seems to be not too much more expensive. If I'd seen that before ordering this one I may have gone for it but I'm not too worried now. On the whole I like this compass a lot.

It's not a fast compass to use and it's not something you would tramp along with in your hand, so it wouldn't suit orienteering for example. In practice I only tend to use a compass for navigation when I want to check something, and accuracy is what really counts then.

So yes, I think this is very good value at the prices available at this time.

It’s not quite my ideal compass yet, but it’s nowhere near as expensive as a prismatic compass which is a pretty close contender.

I have made some minor modifications to mine since writing this. Possibly most important, I have marked part of the North end on the needle in red. It is quite easy if not paying attention to take a reading with the South end of the needle by mistake. Red draws the eye more than white so should reduce that risk.

For my own use I’ve also added a compass rose marked with average sunset and sunrise positions for the UK.

As a landscape photographer, this is probably one of my most regular uses for a compass so it saves me carrying a separate table with me.


	I sourced the small protractor/romer that you see in the top illustration from Maptools and drilled a small hole in the centre for a thread which can be used for taking map bearings. Last but not least, I adapted my pocket magnifying glass so that I could use it for close checking of the scale without the metal rim deflecting the needle.

Bushcraft and wilderness skills should always be practised with respect for the environment and other users of the outdoors. Leave No Trace.