What's the advantage over a catamaran or hydrofoil ferry?

Cavitation limits hydrofoil top speeds to ~60 knots. Although, there's a neat profile that just ignores top surface lift entirely [1] (probably at the expense of drag?).

[1] https://www.metstrade.com/news/sustainability/record-hunters...

Speed. 290km/h is pretty quick by maritime standards.

And comfort. With a 1.5m swell, you're gonna feel that in a boat. A hydrofoil will still go up and down.

Whereas a ground-effect vehicle is still flying, so a lot smoother.

Hitting a partially submerged log or lost shipping container is pretty rough on hydrofoil ferries.