The wax idea seems like a good one. I’ve used silicone before, and it worked okay. However, I was never satisfied I got all of the air pockets out. It seemed like the maximum
depth it would read before I tried the silicone-in-a-bowl trick was 500 ft., while after I did the silicone thing the max
depth range was 200 ft. It was accurate as near as I could tell in all other respects. Needless to say, except for contour
navigation, it’s the short end of the range I worry about.