I thought I’d tell a story. Loads of marine radios I sell are advertised as waterproof and they float. Some even have a red LED that flashes when the radio gets immersed in water so you can find it in the dark.
One radio is sold by many people in the UK - Recent RS-25, which is also the Vitai VT-20 and branded by a big UK dealer with their own brand name. The packaging on all of them states they are waterproof and float. I’ve sold hundreds.
I sold one this week and the customer thought he’d test it. It is indeed waterproof, but sadly he reported it floats as well as a brick does!
I decided to test this and put the radio in a tall measuring jug, turned on and I added water. The water covered the radio and it didn’t float! I told the factory and they didn’t know either. I think the batteries were changed to ni-mh at some point and they are heavier - heavier enough to not give it enough bouyancy! The next model up - subjected to the same test, rises when you add water, and floats - and the red LED flashes. All the sales blurb on the net for the small one says it floats, and clearly, nobody checked it!