Discussion: Southern hemisphere compass

As most of you know a bunch of North American juniors will be heading off to JWOC in Australia next summer. With that comes the purchase of a new compass. If anyone in North America has one & would like to sell it, please post here.

Better than that, if anyone has southern compasses they would like to donate to the Canadian (or presumably the US) JWOC Team that would be appreciated. We discussed this idea at a JWOC team meeting and thought there may be enough old timers/alumni that have such compasses collecting dust in shoe boxes that they might be willing to donate. If that's you, please contact me (or a US team administrator). Thanks!

I'm willing to loan mine, but I would absolutely need it back. Its a Silva baseplate (5 or 6S Jet or something like that, I think, the one that runs about $80)

I used to have one in my backbag, a shiny new looking one my father used at WMOC some years ago. I used to borrow it to my friends who had forgotten their own compasses home. It was fun. Too bad they don't borrow me anything any more. I wonder why...

This isn't what we expected. We southerners rely on exiting northerners to sell us their almost new southern hemisphere compasses.

Just be like me and not use a compass, its way better

I concur with Pensioner. However I have a perfectly good compass purchased when I lived in the USA. It does work in Australia if you hold it above your head and angle it whilst running. And you can read it easier if you turn it upside down. This may sound weird, but is not if there are enough of you doing it. I have never had a problem using this technique. And holding the map in the air also gives shade protection from the sun. This is important in Australia where we have the giant ozone hole causing exposure to high levels of ultra-violet radiation and the real risk of skin cancers to anyone not wearing a full body suit.

I think an ad or announcement or something like that in ONA would be a good idea - there are likely a lot of non-AP readers who might be willing to loan a compass to the junior team.

I say only the american jwoc team gets to buy compasses when they go to austraila and then the danish.

I am a member of this years jwoc team to lituania from south africa. We cannot buy northern hemisphere compasses here and luckily some of the american team and the ones running in the spectator races were able to lend us compasses.
The danish junior coach also came through by giving me a compass when i stupidly left mine at the hotal.

Lets keep the advantage down under with the southern hemisphere teams and the friendly northern hemisphere ones.

Yahoo

I think we need to set up a finish chute photo and ask it to be included on the JWOC site.

Seriously, its interesting to see the northern hemisphere suddenly understanding issues we have to grapple with almost every year.

just by a new one.... it will be easier and you will get the one you want. they cost $130 australian dollars for a jet 6 spectra thumb compass. and you will have it for the next time that you come to australia, because you will like australia that much that you will have to come back.

if you're interested,
the man who imports silva products into Australia has a website: http://www.macson.com.au/

unfortunately he charges extortionate rates, and you'd be better off purchasing baseplates through snowgum: http://www.snowgum.com.au/ (they get their silva compasses through macson, but don't retail them for as much)

if you're looking for thumb compasses you'd have to compare prices.

The sentiment of this forum is that people don't want to buy a compass at all, just for one week's run. As far as JWOC teams are concerned this would surely be an opportunity for team management and sponsorship. Could someone do a deal with a compass supplier to hire compasses for the week, at the end of which the compasses get returned to the supplier for resale (still at a profit) ?
Are the organisers doing anything like this for the JWOC teams?

Let's be fair to Macson Trading. They are the Australian agents for Silva and distribute to retailers. They can't undercut their retailers. If you buy from them you should expect to pay full price unless you can come up with a good reason for a discount. Tom was one of the founders of orienteering in Australia and has been a strong supporter of Australian orienteering. The base plate market in Australia is fairly competitive at the low end of the market. Thumb compasses being for a smaller selective market are more expensive.

no it's just that the majority of retailers sell their base plates (which they acquired through tom) for a significantly lower price than macson. I understand that this is because of higher competition (hence why they are flogging them in the first place). I just feel that Tom needs to reduce his prices in order to be a viable option.

I don't think the organisers should be responsible for ensuring that the runners have a compass - it's the responsibility of the competitor to be prepared for the race. However, that doesn't stop any potential competitor for approaching individuals, clubs or even OA about borrowing a compass for the week.

yeah i agree organisers shouldnt have to do a thing as they have to do so much other things to do....

the way that i see it is that its not just for a week... as there is the training camp as well ( and you probably still will not be that used to australian terrain, so come a month early.) and you also will have if for a life time and will probably use it too if you participate in the world masters when you are over 35(yes its a long way away i know.) and yes it is a chance for the national body to try and gain some sort of deal off a silva supplier, like orienteering australia gets for all the junior teams.

but this is just my opinion of what i would do and others may want to do different.

Darn Aussies, you got me again:) Was I the only one fooled this time?

I assumed that this thread was another example of Aussie humor (ala 'drop bears', etc); but finally decided to Google it.

Here's a clear explanation from Heather Williams of Williams College on the mechanical difference between northern vs. southern hemishpere compasses.

http://www.williams.edu/Biology/Faculty_Staff/hwil...

Also, Silva/New Zealand has a global map of their 5 official compass zones - with Aussies and Kiwis having their own zone (of course!).

http://www.ampro.co.nz/products/silva/silva.htm

Wow, New Zealand has 23 degrees declination - sure could mess up foreign Adventure Racers! (Of course, O maps are drawn to magnetic north - 'no problem'.)

Funny thing is, it seems like the two-point bearing design of Moscow compasses should make them latitude-independent, but I've been told that they do very badly at the wrong latiutude. Don't know why that would be. I think I've heard that Recta makes (made?) a compass that actually does work at all magnetic latitudes.

Hello,

I was/am the coordinator the recently held 7WRC which held to the East of the JWOC venues.

Whave a mixture of baseplate and what I'll call wrist/thumb strap Jet,silva compasses that cou dbe hired or purchased. I think we would prefer to sell to be frank as we are a volunteer organisatioon and don't want more work!

May I suggest that you should be contacting the organisers - NSW Orienteering to see what arrangements they maybe planning.

We delat with Mascon Trading I have not complaints about their trading and pricing methods. They are entitled to make a living. The market after all will decide if they are too expensive!

Cheers,
Alan Mansfield

Looking at the map Ricka linked to, it seems like you'd need different compasses for South Africa and Australia. Is that actually the case? Do South Africans have to buy Aussie compasses too when they go to JWOC?

It's off by only one zone, so it probably wouldn't work too badly, not like taking an MN compass to Australia.

Now, an NME compass, that must be a rare thing. Can't imagine they sell too many of those. Designed pretty much exclusively for Sahara travel.

Now, an NME compass, that must be a rare thing. Can't imagine they sell too many of those. Designed pretty much exclusively for Sahara travel.

Well, it does include the southern half of China. I never knew about the different magnetic zones though. All this time, I've been orienteering in the US with compasses bought from Hong Kong (which lies almost right on the line between MNE and ME). Haven't noticed any difference, but I'm not even sure if they were actually calibrated to the correct zones.

Silva compasses (some of them, at least) have a marking on the capsule showing what zone they're for. Anybody out there have anything other than an MN or an MS?

I've had more trouble with my northern compass in the Yukon than my Australian compass in South America (where it seems to work ok), even tho it is in a different zone.

In South Africa, I've always used an ME compass. I only realised it wasn't actually designed for us a few months ago, so its hard to notice any real difference. Apparently the SME ones are hard to find. I guess you could take a SME to Aus, maybe even an ME.
But my dad uses a recta baseplate which you can use anywhere. Probably a bit expensive though

Iv got two silva thumb compasses.
NH jet has NW as the code
SH ? has SME
Hope this will help.

> NH jet has NW as the code

That's MN. You're looking at it upside-down.

Oh my bad :)

I just took out my Northern Hemisphere Silva Jet, which I was using in Japan, and lo-and-behold, it points perfectly to north in Australia.
The letters on the back are MNS

The issue isn't that it won't point north. The problem is that the needle won't sit level, and will tend to drag.

"it points perfectly to north" = "it functions perfectly"
You say that the needle won't sit level. But it does.
You say that it will tend to drag. But it doesn't.

I wouldn't use my European compass in Australia. After coming back from JWOC it was the only compass I owned for a short while. It did drag and it wasn't level. You could use it with patience.
I'm keeping my European compass. I intend to go back. It would be nice to think that JWOC competitors and spectators would leave Australia with reciprocal feelings.

The problem is not precisely that the needle will necessarily drag when in a different zone than it was made for.

The magnetic field does not pull the needle parallel to the ground, but rather a bit into the ground, most places. To let the needle spin freely when the compass is level, the needle is counter-weighted to counteract the "dip". But that just means that when you take a compass to another zone, then it will be optimally weighted for holding at some angle other than level, in theory.

When I'm orienteering, there are lots of forces on the compass, sloshing the fluid in it every which way. And, there's no perfect vertical reference anyway. So, the difference due to running with a compass from another zone may not be so totally obvious, depending on how good you are at keeping the needle free when running. I've found the effect of compass zones to be a subtler thing than often described. (Though, for the only vastly different zone that I've O'ed in, NZ, I recall that I had a "universal" compass. But between southern US and northern Scandinavia, the effect is not so major I find. I could imagine someone not noticing it, or only noticing the occassional pinning.)

We were checking out James' Spectra Jet which he bought in Japan. See note above. There does not appear to be any dip on it although it is supposed to be for the same zone as my North American compass which has a marked dip. He's going to run with it tomorrow and see what happens.

Since the weights used to balance the needles are blobs of paint I understand, and they're probably all getting balanced in the same factory for all zones, I wonder how accurately and consistently they're balanced. Plus magnets often lose or change magnetism over time. (The balance weight needed depends on the strength of the magnet, as well as on the desired zone.) Maybe it's worth seeing if you have an old compass that's dragging needle, and figuring out whether it is now correctly balanced for another zone, before buying one for a distant voyage.

I don't know what the magnets used in orienteering compasses are made of, but I would imagine it's something similar to alnico, which Brunton uses in some of its other compasses. The Curie point of alnico is about 800C, and even if they're not using alnico, they're hardly using something with a Curie point as low as, say, the melting point of your baseplate. So as long as you haven't melted your baseplate and you don't leave your compass in a box of magnets, the magnetization should be pretty constant over time.

Modern fancy compasses use rare-earth magnets, I think. Older or cheaper ones probably use mild steel. And the older ones can spontaneously reverse. I was skeptical about this until it happened to one of my compasses in the spring of 1993. Red end points south now. And being balanced the wrong way, it definitely drags now. If I ever magage to get to Oz or NZ, I'll bring it to see if it works there (with the wrong end pointing north).

As far as leaving a compass in a box of magnets, there are storage cases available that will hold a couple of dozen compasses, for people who need them for teaching purposes, or for rental at meets. Such compasses may wind up stored on a tilt so that the needles can't swing, and they're surrounded by other needles that may be pointing in different directions. Seems like an invitation for disaster, and I've heard anecdotal evidence of such compasses get screwed up.

As written above, I tried out my MN compass today and it worked fine. Using an Australian one would have been better as the MN compass took a little while to adjust sometimes if it wasn't adequately flat (but I didn't lose any time on it). It was no worse than using a compass with a thin needle that takes a while to adjust.

Spending how much to travel from Europe/US to Oz, and not willing to pay $130 Aus for a new compass to compete in the World Champs??

James, what brand and model of compass are you using?

I think there is a great opportunity for australian orienteers to rent out compasses for a week or so. I have a couple and am willinf to let hem be used for marginally less than the cost of a new one.
You definitely need a southern hemisphere one, as my northern hemisphere one drags and can't be relied on when used in the heat of a race situation.

It's a Silva 6 NOR Spectra Thumb compass. (Sorry, I'd previously written that it was a JET, which I thought it was).
http://www.silva.se/templates/Products____106.aspx...}

Modern fancy compasses use rare-earth magnets, I think

Moscow uses Nd-Fe-B, to the best of my knowledge.

My southern hemisphere compass points at the floor in the NH :(
It was something i knew was a problem before i left but i thought it would just point squiff.
When i wanted to buy there there were none to be found for the first 2 days.
Americans lent me and the the Danish coach gave me a silva jet (thanks again :))
It will be a problem for the NH ppl so buy before going to oz