TackTracker

You must keep your GPS dry.  Salt water and electronics do not mix - and will void your warranty.  Here are some options:

1. Use a BlueBottle Pocket Pouch (www.bluebottles.com.au).  This is my recommended option.
2. Put it in two sealed zip lock bags, one inside the other to give a double seal.  This works - but is susceptible to problems - as its easy not to seal the bags correctly.  Also, the bags deteriorate.
3. Attach a waterproof plastic container to the boat and put it in that.  Look for a good seal, and latches that ensure it can't fall out. 
   • The Pelican case 1010 (www.carryitcases.com.au) for $20 is a great solution and very high quality.
   • AquaPac pouches also look good

Important: Do a leak test without your GPS first!  I tried a promising looking Clip-It case from the supermarket and it failed spectacularly!