Reversing The Polarity – are magnets a risk to safety in the mountains?

If you’re venturing into the wilds and going to be doing some proper map reading and using a compass (or might need to do so to rescue yourself), then Mountaineering Scotland has issued a press release which warns you to pay attention to what you’re wearing.

Apparently magnets may not be such a great substitute for pocket closures – and certainly we’ve seen a few items of mountain bike clothing where magnets are used for closures, to stop hoods flapping, or to keep your hydration hose in place. Why? Because you might inadvertently reverse the polarity on your compass. It might sound cool, but it won’t launch you into hyperspace – and could send you in completely the wrong direction.

To be fair, riders at trails centres are unlikely to need a compass, and even riding local natural trails you’re rarely in need of a compass – except perhaps in disorientating fog or snow. And if we’re being honest, how many of us actually have a compass in our packs?

However, it’s still worth bearing in mind where you keep your compass, because if you do find you need it, you’ll want it to be working. Read the full press release for a cautionary tale:

Mountain safety experts have warned against a worrying trend in the outdoor clothing market.

Magnetic closures on gloves and jackets are being marketed as the modern alternative to Velcro or poppers.

Magnets are well-known for deflecting compass needles, and there is already evidence that this may have been the cause of a recent Mountain Rescue call-out.

Heather Morning, Mountain Safety Adviser for Mountaineering Scotland, said: “We have reviewed the circumstances of a recent incident in the mountains east of Glen Shee, which involved hundreds of hours of rescue personnel hours and police time.

“A group of walkers were caught in low cloud and headed east instead of west, becoming totally disorientated and ending miles away from a road. Fortunately no-one was hurt – just pride dented – but it could have turned out so much worse had mountain conditions been more severe.

“The reason for the error was the compass. It had been stored in a pocket next to a mobile phone in a case which had a magnetic closure on it, and the magnet had reversed the polarity of the compass needle, so that the north arrow pointed south.”

This phenomenon of ‘reversed polarity’ has been widely publicised in mountaineering circles and people are advised to keep their compasses well away from mobile phones. But there is concern at the growing use of magnetic closures in outdoor clothing. Popular outdoor brands are producing mitts/gloves with fold-back flaps using magnetic closures and there is a wide choice of outdoor jackets out there replacing Velcro with magnets hidden away in folds of the garment. Pockets, hoods, front fastenings, wrist closures… they’re all out there.

Heather warned: “Modern technology is great. The resources available now to keep us warm and safe in the mountains have never been better. But more joined-up thinking is needed between outdoor clothing manufacturers and mountain users to avoid potentially life-threatening consequences.

“My advice is to steer well clear of any garments utilizing this latest trend of magnetic closures or you could end up with an expensive bill for replacing your compass or – worse – a life-threatening navigation error.”

Hannah Dobson

Managing Editor

I came to Singletrack having decided there must be more to life than meetings. I like all bikes, but especially unusual ones. More than bikes, I like what bikes do. I think that they link people and places; that cycling creates a connection between us and our environment; bikes create communities; deliver freedom; bring joy; and improve fitness. They're environmentally friendly and create friendly environments. I try to write about all these things in the hope that others might discover the joy of bikes too.

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