No Bras in the backcountry = safer navigation
There are a few articles floating around the internet these days about navigation and the dangers of your compass suffering from reverse polarity. This means that your compass shows North as South or South as North (or some where in between). Magnetic fields exist around many items we commonly carry with us on the hill – mobiles, avalanche transceivers, radios, personal locator beacons, GPS, cameras, car keys, small magnets on belt fastenings and underwired bras.
What was that last one? The underwire on bras? Yup.
Wearing certain types of bras could end up making potentially fatal navigational mistakes, experts have warned.
Outdoor enthusiasts risk making errors because items they wear or carry – including underwired bras – can stop compasses from working, the Mountaineering Council of Scotland said.
The group, who represent 11,300 climbers and walkers, said incidents where compasses were affected by reverse polarity were on the rise.
They claimed magnets in mobile phones and GPS devices, metal car keys and bra wires could affect compass needles.
The council’s safety officer Heather Morning highlighted the issue after it was raised by Nigel Williams, head of training at Glenmore Lodge, near Aviemore.
She said needles could be switched from point north to south, sending people in the wrong direction while trying to navigate off a hill or mountain in bad weather.
Heather herself has experienced reverse polarity on three occasions in the past three months.
Prevention: A compass is a precise measuring instrument and should be treated accordingly. Your compass should be kept well away from all of the above mentioned items and well clear of magnets and magnetic fields which are associated with electrical circuits and ferrous metal objects.
Cure: Kevin Thomson, Marketing Manager at Silva Ltd says 'It is possible to ‘reverse’ the reversed polarity using a strong magnet. This can be achieved by quickly flicking the magnet outwards along the ‘north’ end of the needle. Repeat vice-verse. Always ensure you compare with a compass that is known to be correct. Note: If you are unsure how to CURE your Silva compass: SILVA will always take back and re-magnetise your compass, no matter how old the compass is.'
Can the compass be used in its ‘reversed polarity state by using the ‘south’ instead of the ‘north’ arrow? In my personal experience (this problem has happened to me 3 times in the past 12 months) the needle does not invert by exactly 180 degrees. It would appear to be approximately 10 degrees out and therefore using it in this state is not reliable.
Golden Rule #1. Keep your compass in a separate location to other electronic gizmos you carry with you on the hill and ensure when you are using it, that it is held well away from your body.
Golden Rule #2. Ensure you read the contours on the map. You should have a very clear idea as to what should happen under your feet as you walk on your compass bearing. If this is not happening, the alarm bells should be ringing and you should re-evaluate.
Golden Rule #3. Always carry a spare compass in the event of malfunction, damage or loss.
Golden Rule #4. Try to get into the habit of checking that your compass is working correctly prior to leaving home.