Thread: Map and compass techniques

Originally Posted by Shooter

These wise words from my father always see me right...

1. The compass is right
2. The map is right
3. You are wrong

Doubt the doubt and trust your tools.

Them's wise words alright

I've had plenty of times that my inbuilt navigational sense has been at odds with the tools -invariably the tools have been right.

Points I've noticed about my own estimations
1/ At the end of the day when I'm tired, I tend to underestimate how far away camp is - I'm buggered and I'm willing myself to be closer to my food and bed than I actually am.
2/ When I've been moving in slow careful stalking mode I overestimate how far I've travelled. If I stalk up a spur or stream from the main valley I'm always shocked as to how quickly I get back to the start point once I've switched back to tramping mode.

When what the tools are indicating to you is a suprise the question to ask is How have I screwed this up? rather than What is wrong with this bl**dy compass? !
Ignore your ego - it tends to talk Sh*t

Originally Posted by LBD

Wise words alright... but move the compass around a bit to ensure nothing is causing a local deviation... Proximity to magnetic fields from phones/GPS/Iron sand concentrations/guns/head lamp batteries, any old iron... etc.

Good point LBD and ensure the compass is level and the needle is able to swing freely.

Originally Posted by Pengy

I used to do this with my gps, but since changing to track up at someone's suggestion, I find it much better. @Gibo. Have you calibrated the compass on gps, and is it a model with triple axis compass? If it is not, then you have to be moving to get an accurate reading

Yip triple axis, might get into the habit of calibrating on each outing.

Originally Posted by Gibo

Yip triple axis, might get into the habit of calibrating on each outing.

Definitely re calibrate if you take batteries out between trips, or for replacement

Just on the compass is always right..it is untill it isnt, there are parts of this island where a compass is useless.

Originally Posted by veitnamcam

Just on the compass is always right..it is untill it isnt, there are parts of this island where a compass is useless.

SI bro? Where abouts?

In behind the 5mile lagoon south of Okorito is one.

Originally Posted by Tussock

Step into my office

Mineral deposits(what I assumed to be the cause) or some kind of magnetic field worm hole?

Aliens, definitely aliens. Obvious place for them to make initial probe.

Originally Posted by veitnamcam

Mineral deposits(what I assumed to be the cause) or some kind of magnetic field worm hole?

I think you have found his stash

Okay ...Okarito... if I recall my history, there was at one time a degree of shipping of timber from Okarito ....back in the day.

And there was a similar practice in Havelock (Marlborough Sounds).... Ships would sail out from the mother country where they had loaded the holds with Ballast rocks... now the greater the density of rock, the less volume required, the lower the centre of gravity and the greater the ships GV moment or righting force.

The ballast of choice was a high iron content rock which was also very magnetic.... I cannot say for certain that is the case in Okarito... but out from Havelock there is a local magnetic anomaly is a result of piles of such ballast.

Originally Posted by LBD

Okay ...Okarito... if I recall my history, there was at one time a degree of shipping of timber from Okarito ....back in the day.

And there was a similar practice in Havelock (Marlborough Sounds).... Ships would sail out from the mother country where they had loaded the holds with Ballast rocks... now the greater the density of rock, the less volume required, the lower the centre of gravity and the greater the ships GV moment or righting force.

The ballast of choice was a high iron content rock which was also very magnetic.... I cannot say for certain that is the case in Okarito... but out from Havelock there is a local magnetic anomaly is a result of piles of such ballast.

Interesting, this is an area inland from the coast tho.

Also would this not have made navigation on said ships rather difficult?

Originally Posted by veitnamcam

Interesting, this is an area inland from the coast tho.

Also would this not have made navigation on said ships rather difficult?

No more difficult than on a steel ship... swing the compass... prepare a deviation chart and compensate for any deviation..

True Variation Magnetic Deviation Compass.... TVMDC... when calculating headings from True to Compass at sea.

But you are right... it is not likely the ballast was dumped at sea 25km inland... um...?