re: floating or not...
The little information leafelet glued to the backof the ACR PLB-375 says it Will Not Float
. To make it float you have to purchase a little neoprene pouch.
We are not sure if we get the neoprene pouch for our two PLBs. We know that we will tie them to our self inflating life jackets.
But then the problem remains: Imagining the worst case within the worst case - what happens with the PLB if you are in the water and for some reason are not able to hold it up above the water so that the antenna can do its work and the GPS has its clear view to the sky...
Guess, we have to do some testing in the tub, or - more realistic - in the swimming pool with the antenna unfolded.