The loudness is definitely a problem, but it looks like there's headway being made on helicopter noise-reduction that could be transferred over to hovercrafts.

The loudness is definitely a problem, but it looks like there's headway being made on helicopter noise-reduction that could be transferred over to hovercrafts. On second issue, do you mean rocks and sharp objects that could be thrown from the air being pushed out? I don't know how applicable it is to hovercrafts in this situation. We're either pushing air up or down, not side-ways. I don't imagine a rogue knife will be a problem for anyone else but the owner of the vehicle (a quick-fix would be to use a catcher cage). But none of thee issues damn hovercraft. It'd be more likely the technology's just not at a practical level.