> I assumed it was compressed air, that once you had a 'full' (at pressure) tank Even so, it probably still requires electricity to activate the solenoids to o

> I assumed it was compressed air, that once you had a 'full' (at pressure) tank Even so, it probably still requires electricity to activate the solenoids to open the valves or whatever. I'm speculating since I don't know how large boat horns work, but I wouldn't be surprised if they require power.