Need another compass?

[redflex]

May sound silly but I am off to the Phillipines and bit unsure on my compass,

Will my Uk compass work or will I need one which is global ?

Read many different views can anyone help?

 

[spamel]

I used a normal silva compass in the Falkland Islands, which isn't quite the end of the world but you can see it from there!! I didn't have any problems, I think they are only required if you want to be ultra precise. It shouldn't be that far out, and when you take into account that magnetic variation is normally a couple of mils, you can't even measure that on a compass, unless you use a prismatic.

That's my experience of it anyway. Let's see what others say.

Spamel

 

[greg2935]

If youre compass works here it will work there (baring magnetic stratas etc.)

 

[KIMBOKO]

It will still work but

"In the northern hemisphere the north end of the needle is pulled downwards, and the south end is counterweighted to balance the needle. When you use a northern hemisphere compass in, say, Australia, the south end of the magnet is pulled downwards by the magnetic field, and is also heavier than the north end - resulting in a needle that catches and drags on the bottom of the compass housing when the compass is held horizontal. "

This obviously applies depending on how far north or south you go from the area that the compass was designed for. But obviously with a hand held compass you can make a suitable adjustment.

 

[Schwert]

According to Suunto's compass zone chart a compass balanced for zone 4 (I think) would probably be better for use in the Phillipines...or a global needle.

I have a global needle Suunto ranger type compass and it really is a gem, it worked perfectly in Kenya.

 

[Lithril]

Silva do a compass (I'll check the model later) thats designed for use worldwide. If you're going to need accurate nav, ie walking on bearings/micro nav etc make sure you check out the magnetic variance for the area.

 

[Stevie]

found some interesting reading the other day on this. Have a look at

http://www.meta-religion.com/Paranormale/Bermuda_triangle/magnetic_variation.htm

if it helps??

 

[leon-1]

I have used the Silva type5 and the Suunto Militaire all over the place, Kenya Canada and South Georgia. They were all on issue in the forces and they all worked no matter where you were.

Grid magnetic variation is just part of using a map and compass, as long as you check it on the map sheet that you are working on you should have no problems.

The old way of remebering was always

Mag to Grid Get rid.
Grid To Mag Add.

 

[Stuart]

You may find you have problems with needle dip, something I experienced for the first time earlier this year in Malaysia

As KIMBOKO pointed out:

"In the northern hemisphere the north end of the needle is pulled downwards, and the south end is counterweighted to balance the needle. When you use a northern hemisphere compass in, say, Australia, the south end of the magnet is pulled downwards by the magnetic field, and is also heavier than the north end - resulting in a needle that catches and drags on the bottom of the compass housing when the compass is held horizontal. "

This is a simplified example of what happens when a needle for zone 1 is taken to zone 4

Not all compasses are adversely effected by this the Silva type5 for example does not seem to be noticably effected.

Compasses that employ a disk type 'needle' seem to be more prone to needle dip and it is often noticed on prismatic sighting compasses where the needle dip causes the markings to appear out of focus when sighting.

If your compass is effected the needle may drag on the bottom of the housing and not rotate freely

As I am sure you are aware you will need to use different values to calculate magnetic variation in the Philippines the co-ordinates for manila are:
Lat 14° 35’ N , Long 120°57’ E

So the magnetic variation is currently 1.16 W

Whilst it is not relevant in this instance as the magnetic variation for the Philippines is to the west it is worth noting that the “Mag to Grid Get rid, Grid To Mag Add” Rhyme only works when the variation is to the west, it is reversed when the variation is to the east.

 

[Pict]

I found my compass fromt he USA didn't work for beans here in Brazil. The needle dip is extreme such that it makes contact with the case and won't turn freely.

I picked up a Recta DP-2 down here and it works great. I used in PA this past year and it worked there as well.

If I were to make a north to south trip I would buy a global compass and not look back. Mac

 

[redflex]

Thanks for all your info and links,

I will be working in a rainforest for a month, treking out to sites to work.

GPS not great in forest so will need a very good compass which I must be able to trust.

I think I will go for one of the Suunto, as a cheap compass may just prove to risky if things go wrong.

 

[AUSSIE]

Turn em over and look at the bottom of the compass capsule!! Simple if they are marked mn (Meridian North) as in the ones you buy in the UK then they don't work so well in the Suvvin hemisphere mate! Here all our's are marked ms ( Meridian South) or similar!!!