Will 433 mhz radio freq work under water?

[DeepSeaExplorer]

Sonar works in the 50 to 200 KHz range (or 0.2 MHz) because those low frequencies can propagate thru water. Years ago, I operated a side-scan sonar in the 100 KHz range that dolphins tried to communicate with because they could hear it from a distance. Sonar is sound which as divers know conducts well thru water.

400 MHz is Ultra High Frequency (UHF) which is Radio Frequency (RF) which has different properties. No one can hear it because it isn’t a sound wave, and is more easily absorbed especially by water.

Sonar uses a transducer to convert electrical energy to sound. (That’s why I call those AI transmitters transducers.) UHF is RF and uses antennas which don’t work underwater. I wouldn’t expect UHF to work at all, unless it’s inside a submarine.

 

[Waterwulf]

I'd worry about a momentary loss of control causing a runaway. Once it gets far enough away, it's out of control anyway. What about Reed switches and a transistor power control system like used in electric radio controlled models. Fifty plus amp R/C controllers are no big deal. You could even set up a Reed switch with a wrist lanyard to prevent fly aways.