Nice pictures and stories, but no answer to the actual question.
A hovercraft has to maintain a cushion of air. That means that it can only handle waves that are small relative to it. You never want even one wave to wipe out that cushion.
So a hovercraft has to be big. It doesn't want to go over open water with large seas. Therefore it winds up going over short stretches of relatively sheltered water. Given its speed, it will make many trips. You want it carrying people every time. So you need a high volume of potential traffic.
However when civil engineers see a short stretch of relatively sheltered water separating people who want to go back and forth, eventually they build a bridge or tunnel there. And then nobody needs that hovercraft any more.
Now we can improve hovercraft technology. We can possibly find new routes where the new hovercraft makes economic sense. But eventually that too will be doomed by the same facts. We have ever improving bridge and tunnel technology. And the hovercraft always loses once one of those is built.
If thats the case, i do wonder why both USA and Russia have hovercrafts in their navies. Hovercrafts that at least in the US case is supposed to handle landing troops from beyond the horizon rapidly. If they can't handle waves then they seem oddly limited for such usage.
My understanding is that the US tried hovercraft out in Vietnam, and then abandoned them. By contrast the Soviet Union put a lot of effort into them.
For military use, hovercraft have the ability to travel on water, mud, ice, and fairly flat land at very high speed. These are very interesting characteristics that are worth some compromises. The case for them is more compelling if you are considering military engagements on a variety of difficult terrains near you (like the Soviet Union was) rather than only engaging in military engagements that take place large oceans away (like the US). Plus several military targets for the Soviet Union were across relatively calm water (the Baltic and Black seas) which look very, very different than the open Atlantic and Pacific.
Secondly, military hovercraft do not need the same reliability when faced with waves. Not being able to handle a once in a hundred year wave would be a problem for a commercial hovercraft that is hoped to be in constant service for decades without a crash. For the military, if you can only deploy it 80% of the time, then you're happy that you've got an 80% chance of having it available when you need it. So they don't have to overbuild so much.
Besides, a once in decades of operation disaster doesn't seem like such a priority when you're worrying about enemy fire!
I was aware that a handful of Bell SK-5s were used during Vietnam and then disbanded. I didn't realize that the US military had continued to develop the idea.
I did a single channel crossing on a hovercraft back then. neveragain.
I'm pretty sure I'm an inch shorter since that trip. The sea wasn't terribly bad (by channel standard) but the journey was absolutely horrendous, felt like someone kicking you repeatedly in the butt for the whole way.
So yeah, fast, and cool, but hey, I'd rather sip my coffee on a ferry any day instead of having to hold to the chair I'm sitting on :-)
Growing up, if the wind was right, I used to be able to hear the Ryde-Southsea hovercraft mentioned in the article from my bedroom window, about a KM away. It's still a really exciting way to cross the Solent. And slightly cheaper than everything else (which is nice, because the Solent is incredibly expensive to cross).
A hovercraft has to maintain a cushion of air. That means that it can only handle waves that are small relative to it. You never want even one wave to wipe out that cushion.
So a hovercraft has to be big. It doesn't want to go over open water with large seas. Therefore it winds up going over short stretches of relatively sheltered water. Given its speed, it will make many trips. You want it carrying people every time. So you need a high volume of potential traffic.
However when civil engineers see a short stretch of relatively sheltered water separating people who want to go back and forth, eventually they build a bridge or tunnel there. And then nobody needs that hovercraft any more.
Now we can improve hovercraft technology. We can possibly find new routes where the new hovercraft makes economic sense. But eventually that too will be doomed by the same facts. We have ever improving bridge and tunnel technology. And the hovercraft always loses once one of those is built.