That’s right! Hydration bladders can ruin your navigation without you even realising it.
Over the past year I have noticed an increasing problem of clients compasses being effected by unknown magnetic forces – apart from the magnetic poles of planet earth!
On one occasion the effect was so great that it was causing the magnetic needle on the compass to swing around wildly up to 500 degrees of variation and for no apparent reason.
Armed with a highly sensitive compass, we decided to use it a bit like a metal detector and moved the compass around all over the person who was having problems until we found the area for concern.
We finally found out that it was the bite valve attached to the end of the hydration bladder drinking tube. It contains a very heavy duty magnet that allows the bit valve to be stuck to the chest strap on your small rucksack when running or riding your bike, keeping the bite valve in place. However this is no good for you if your in the hills and mountains navigating in the dark or poor visibility using a compass and map! as it was demonstrated to throw your compass off magnetic north from as far away as 18 inches!
So please please please check your Osprey or Camelback drinking tubes to see if it is the magnetic version, and perhaps swap it back for a standard non-super-magnet version, then when you are with us on one of our navigation courses we wont be left wondering why you have just walked off in the wrong direction 🙂