Originally Posted By: TheFallibleFiend
Paul,
Again, I didn't see the mythbuster's episode, but unless they were somehow using the compressed air to power a prop, I don't understand the relevance of your reply.


I can see what Paul's saying. I'd certainly expect some difference in efficiency between underwater and out-of-water. But it might even be the other way round and wouldn't be enough to make it practical for actually travelling to places. Maybe enough for some sort of joy-ride tho.

Another weak reason why it still wouldn't work is after the boat got so fast the pipe was out of the water, that should have slowed it down until the pipe was back underwater, then sped up again, so basically got to some equilibrium position. But it didn't, it just ran out of air after a brief moment out of the water.