A while back the forum was discussing how to carry various GPS.
Lyn and I have been using a bag called Paqua Mobile. We bought them at Whitworths for about $30.
Certainly they are waterproof. At first they were a bit floppy but we have worked out an easy mod which involves lengthening the loop that carries one side of the locking catch. Just use a bit of neoprene and make the loop about 25 mm longer. Any sewing machine will do this. This mod allows the other end of the bag to fit around the mast making the whole attatchment much more secure and the contents easily viewed while sailing.
As good as the GT-31 is it does not allow the user many options while on the water. On the other hand the Garmin displays such helpful data as Max speed, Current Speed and Distance traversed.
I use a Garmin strapped to mast and carry the GT-31 on my arm in a bag that Lyn made but, unfortunately, does not allow the instrument to be viewed.
Recently I noticed on the Paqua site that they are releasing another model called the Paqua Midi which may be ideal to wear on the arm.
I hope to get hold of one of these and test it.
javascript:parent.insertImages('

')