Compass

[proskub]

I need to buy a compass. What sort should I get?
I have an old dodgy one from my Dad, but I suspect thats its a bit dodge. I've been looking at the mirror ones, what do people think of these as a walking compass?

[vagrom]

If you want a simple "entry level", reliable compass, then it really only needs to be a Silva Compass, from Sweden. The "Field 7" sells at Paddy Pallins for $37 and that's really dear enough. Typing "Silva Compass" into Google will help.

[Cocksy_86]

Just get a stirdy one. I had a compass that broke and the oil dissolved all the light plastics and fabrics in the bag.

[Lindsay]

If you want a simple "entry level", reliable compass, then it really only needs to be a Silva Compass, from Sweden. The "Field 7" sells at Paddy Pallins for $37 and that's really dear enough. Typing "Silva Compass" into Google will help.

I agree. A basic Silva compass will be all you need for most bushwalking navigation. Simple to use, sturdy and reliable.

[Charlievee]

+ 1 on the Silva. Reliable design and available everywhere. Regards, CV

[proskub]

Thanks guys. I'll go and have a look with that in mind.

[sailfish]

I don't think the type really matters that much. You just use some variation in technique to suit what you have. My son chose a large mirror one so it doubles as a signalling mirror etc. I like the duel purpose idea. I use a Suunto KB14 (I think it is) because that's what I got when I worked as a geo technician. It's a field survey sighting compass good to 10 minutes of arc or so, into the survey calculations territory. Not really designed for bush walking and not the best thing for that purpose but it's what I have so I use it. The Silva ones with a scale arm can be used as a protractor for plotting on a map without using the compass so minimise magnetic errors. You can plot with almost anything but not necessarily without using the compass. Each type has its pros and cons. Don't put much emphasis on sighting, it's not something you will get to do much anyway but some kind of basic sighting ability is a good thing.

I'm sure everyone has their favourite.


Regards,
Ken

[Son of a Beach]

Be careful if buying a compass from overseas. Make sure it's correctly weighted/balanced for where you are going to use it. See further information at: viewtopic.php?f=15&t=1258 (and the bushwalking FAQ linked from that topic explains it in more detail).

[ninjapuppet]

was with a friend who was shopping for a compass last year.
In the store, they had about 20 different types of compasses and funny enough each were pointing in a different direction for north! I tried to explain to him that its because we're indoors and all those electromagnetic wires in the walls might have some effect. The sales assistant said the same thing.

ok, he bought one, but on our first trip, i got my compass out and compared with his, and both our compasses were pointing in different directions about 30 degrees off! i just laughed my head off and left it at that. mine was only a cheap $30 compass from some army disposal store while his is a $110 mid range silva. Ive never really looked into it, but maybe my cheap one was imported?

[sailfish]

No, the thing about imported compasses is to do with magnetic flux zones. That is, the flux dips at different angles to horizontal depending roughly on latitude. If the compass is used in the wrong zone, the needle or disk will tilt at different angles and may foul the case and not swing freely. Small alignment or calibration errors are quite normal in magnetic compasses. 30 deg is pretty excessive and probably indicates a fault. In navigation, it is normal to calibrate a compass but this may simply be writing down the alignment error so you can add or subtract this to get the right bearing as you do with declination. Calibration can vary depending on which part of the circle you are using. Calibration errors are generally only a deg or so, often too small to take account of in bushwalking compasses where the scale is in 5 deg increments.

Regards,
Ken

[vagrom]

The good thing about good compasses, like the Silvas and Suuntos, is the oil. The needle swings around and stops. I'm not sure about the Swiss Recta and particularly, the American Brunton. Needle sway and tremble is annoying.

[sailfish]

Ninjapuppet

Your 30 deg discrepancy has been niggling at me.
So at risk of stating the obvious, how did you compare the compasses?
You did eliminate all possible sources of magnetic interference didn’t you?

The other compass.
Steel items in proximity, worn or in pack. (glasses, press studs, multi tool, knife, belt buckle etc).
The Ground
Fencing
Transmission lines

PS Even plastic frame glasses have steel screws that will throw sighted bearings off.

Regards,
Ken

[vagrom]

Two things that may be helpful:
-in Tassie, there are some places where your compass will appear to be thinking of something else. The only place i'm familiar with, perhaps from experience or by reputation, are parts of the Central Plateau. I think Ironstone Mtn, for obvious reasons, has a reputation for this. Leaman's The Rock that makes Tasmania has an excellent two pages on the background to this: the magnetism "set" in the Dolerite, at a certain ,as it cooled. See index.
But I can't see that he refers to parts of Tassie where bushwalkers are likely to warn that these areas are renowned for the problem. Does anyone have any info on this? Is it simply a Central Plat. phenomenon?
If you suspect something, from memory I think you can test it by reading the compass while standing and then see if any needle swing occurs if you squat down.

-Also, my compass once went completely drunk up on Mt Howitt. It was fine up in the Gammons then shortly after that I flew down to Melbourne. scouts or Pallins kindly sent it off Sydney (?) for me where they corrected it, saying they'd never heard of it happening before. I can only presume it was the airport x-ray and that I need to remember to pack it in my main luggage in future and not in my hand luggage, where I tend to pack valuables.