I wouldnt trust anything electric. Murphy's Law states that when you most need it, the batteries will fail, or you will get it wet, or you will drop it.
MY ADVICE
Go to a large YACHT CHANDLER (or Yachting magazine) and get a hand bearing compass. Will cost you - wont be cheap. These are designed to be RUGGED and WATERPROOF
and used by yachties.
I bought one over 20 years ago and it is still working brilliantly. You hold it to your eyes and look through to the very accurate scale. Mine was filled with Tritium gas so could see at night. (gas long ago leaked out though.) Heavy rubber sheathing all round, and was neat, you put it round your neck on a string.
You will always be able to get the magnetic variation for your area off the .net, then apply the adjustment (ie in Brissie variation is 12 degrees east, so to point directly south, you set the compass to point 180 - 12 = 168 degrees
)
Good old 18th century stuff for me. Capt'n Cook managed with no worries, mate
