Thinking about the size of the Vexilar floats, which got me to thinking, why not use a piece of pool noodle slipped over the auger shaft to keep it from sinking if it got disconnected from the drill?
Here is a little spreadsheet that I worked up. So according to the bathroom scale, I need 10" of 3.5" pool noodle to float my auger and drill extension. I figure I will put as much as I can on it for factor of safety and to account for dings and missing pieces.
I only need 2" to carry the weight of the transducer.
What do you guys think about it?