I suppose I assumed it was compressed air, that once you had a 'full' (at pressure) tank, you could do a certain amount of blowing even without power. But fair point, I don't really know how they work, and if they are actively electric I certainly didn't know that and obviously that wouldn't have worked and so there's the answer.
> 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.
