Nav App wrap up.....
It was a bit nerve wracking that I might fumble it and watch it go overboard, but thankfully it didn't happen.
Robes' Oregon 450 is waterproof, but I bet it will sink like a rock if it goes overboard (I've got one.) I was comfortable parking mine in a drink holder, but TakeFive suggested a handlebar clamp that Garmin offers if you are concerned about losing it. If your charter boat has one of these open transoms, you might consider a clamp or tether as cheap insurance.