all commercial hovercraft are watertight and buoyant even when the engines are off.

There are still a handful of commercial hovercraft routes.

I heard a hovercraft this morning, pretty sure they insure it, certainly has passengers.

Have heard rumours that they are looking to open up another route but I think its only seasonal and very infrequent. Hope it takes off though - pun not intended, but appreciated.

Never heard of a plane that managed to keep going without power and yet those can be insured. Also you can (apparently most do) make hovercraft with a buoyant hull.

But it's the only British tech innovation of the last 100 years.