I'm looking at buying a new compass
I've got a Kathmandu one and i hate it (it was a gift), it takes ages to circle round to north and you have to have it dead flat to work properly.
I was wondering what make of compasses everybody uses?
RR
Printable View
I'm looking at buying a new compass
I've got a Kathmandu one and i hate it (it was a gift), it takes ages to circle round to north and you have to have it dead flat to work properly.
I was wondering what make of compasses everybody uses?
RR
I use a Silva, kinda the default option.
+1Quote:
Originally Posted by GravelBen
I probably have half a dozen compasses laying around here and couldn't tell you the make of any of them. All point north which is all I care about.
Silva for sure.
Silva....end of.....
Silva expedition
Silva. Had it since intermediate when I did orienteering.
Is there a trend appearing here?
Yep - everyone whose age is still in double figures can remember what sort of compass they have.Quote:
Originally Posted by gadgetman
That is obviously low double figures GB because I am buggered if I can remember what sorts I have. And I am not climbing in the attic to find out.Quote:
Originally Posted by GravelBen
I have had a number of ranger ones.
They get lent permanently:rolleyes:
Take someone out and split up"you got a compass?" "um na" "ffs take this head up there SW is out ok now show me SW"
Quote:
Originally Posted by Tussock
Haha Tussock, you're a funny guy... 7 minutes from "real deal" to "junk"Quote:
Originally Posted by Tussock
Anyone using a compass should learn how/when to add or subtract declination, it is a pretty fundamental part of compass work...
So, what would the practical effect be of using a non "universal hub" global needle compass in an incorrect zone ? How far out would it be ?
Ok, so if I understand you correctly, it is more about needle friction ???
Beg to differ, you add it going from true to magnetic for west declinations, and subtract it going from true to magnetic for east declinations.Quote:
Originally Posted by Tussock
Mountain Safety Council also teaches "subtract" in the context of going from bearing taken on a map to bearing on compass. Bearing off of the map = subtract, if you take a bearing with a compass and bring that onto the map, you add (east declination in NZ)
(Declination) west is best, east is least....
Found this on the Silva website, what they reckon a MN balanced needle would look like in the other zones...
http://www.silvacompass.com/uploaded...nation2_lg.gif
Don't quote me ...
There are I believe six magnetic fields/zones on earth. Bluntly put, the amount of magnetic force/pressure applied to the needle would differ at different parts of the needle depending on your location on earth. A simple example, if a compass set for the NZ magnetic field is used in the northern hemisphere the magnetic pressure acts in conjunction with the counter weight causing the needle to drag as the needle may only swivel on one plane.
The hub allows it to operate on two planes, similar to the way a large "bubble" compass would work on boat. This negates the need to apply a counter weight, the practical effect is your compass is now suitable for use in the north pole or south pole while generally being about x4-5 time the price of a normal compass.
No practical application if you are your average punter hunting in NZ.
IMO, buy a smaller backup compass and keep two compasses on your while hunting. I actually had a compass where the needle needed to be repolarized ... "needless" to say a very disconcerting experience.
Also for those of you learning to use a compass the add/subtract method is old school. Bearing off is the preferred method these days.
Attachment 15844
Who sets out a $40m drilling operation with a compass anyway? :wtfsmilie:Quote:
Originally Posted by Tussock
I'm an old school kinda guy Dan:P My take is that you need to understand the fundamentals, and be able to apply them, irrespective of the type of compass, or wether declination is stated as positive or negative. Like Tussock said, it is not that hard to get it wrong, or to get confused, so helps to practise, practise, practise. I've consciously stopped carrying a GPS cos I found it made me lazy wrt map & compass skills.
MSC is still teaching add/subtract...
Can you explain what you mean by bearing off method ?
I'm a surveyor so can think of plenty of options - total station, GPS/GNSS being the most common methods.Quote:
Originally Posted by Tussock
I'm suprised the work (for mining?) is low enough precision that a compass gives acceptable accuracy, they're certainly never considered an option for survey work. Sure there was the odd survey done with by chain and compass back in the 1800s, but we still get some headaches resolving the errors they left.
If your accuracy requirements can be met by a compass then it is definitely the simplest, most portable and reliable piece of gear though - I'm just surprised thats all thats needed.
Shit aye. Better get rid of my chinese hunk a junk.! $1000us compass hope that thing points towards deer!
Sent from my GT-I9300T using Tapatalk
Sweeeeeet. Should pay itself off pretty quick then aye.Quote:
Originally Posted by Tussock
Sent from my GT-I9300T using Tapatalk
Ah gotcha, yep makes sense for that use. The only drilling control work I've done was surface location for vertical bores - they were trying to locate historic mine tunnels under a site to avoid putting buildings on top of them. Keeping within half metre with a compass is doing well, you must be doing something right!Quote:
Originally Posted by Tussock
A lot of second hand gear hit the market when firms went bust or downsized during the last recession which pushed prices down, there are also a few Chinese manufacturers selling survey gear around half the price of the major players now - most of it uses copies of previous-gen Trimble chipsets so should be pretty reliable too.
from me old TF days
My Grannie Sucks=magnetic -grid-subtract magnetic variation
Grand Mas Arse=grid-magnetic -add magnetic variation.
mind you all compass work was in mils ,so dont know if this is still used.
Tussock talking of F..ups with the math reminds me of teaching a TF artillery crew map resections. I asked one gung ho gunner where he'd placed his 105mm howitzer
Hmmmm-plotted on the map it was smack in the middle of lyttleton harbours main shipping lane.
geez that cost him a few ales at the end of the day!!
