Diving to Test Foam Ballast

   I went diving today at Mansfield Dam, the deepest shore dive I know of on Lake Travis. The water was actually deeper than I was expecting. I was expecting 90-100', but we finally hit the bottom at 115'. I don't think I had ever dove at Mansfield Dam before with the intention of going all the way down. Anyway, I brought a bag of material samples down with me to see how they hold up at depth. My line broke as I was lowering the bag down, but we found it tangled up on the inlet grating while we were descending. Lucky for us.

   As expected, regular polystyrene (packaging styrofoam) didn't do well. It shrunk to less than a quarter of its surface volume, though it was still much lighter than water, and it never returned to its original size after resurfacing.

   The fishing float I picked up, last minute, was fine. It's made from a much harder styrofoam and it didn't compress at all. I can definitely use these for ballast initially when I'm working in shallow water.
   The other samples I brought didn't do well. As expected, multiple other types of foam were all crushed and would be useless as ballast. I still need to try hard rubber and other hard materials.