Originally posted by NZ_Ross I went on the fast ferries a few times, a really good service. They got stopped as they were churning up the sea floor in the Sounds, and causing all sorts of havoc with the marine life as a result. They were allowed to operate at slow speed through the Sounds, but it was uneconomic as they then didn't have that much of a time difference with the regular Cook Strait ferries. So the service was discontinued.
If we had the big fast ferries like they use in the Baltic (I went on one from Helsinki to Tallin, Estonia) it would be really good, but for that to be effective they would need the terminal at Clifford Bay operational.
With Clifford Bay you then get the seismic issues associated with the area. Quite apart from the earthquakes under Lake Grassmere within the last few years, local iwi have traditions about ground movement in the area, and although it's turned into a story involving a fight between illustrious ancestors, it sounds very much like a metaphor for strong seismic activity, so the area is pretty unstable geologically.
Up until the 1960s, Blenheim had a river port that small ships used, and there were direct Cook Strait crossings. The Wairau Bar was a bit hazardous, but I wonder with modern technology it might be possible to come up with some kind of vessel that could make quick, comfortable crossings.
I know the Russians did quite a bit of work on ground effect craft, but they never seem to have been commercialised anywhere, and I guess their may be both economic and operational reasons why not. They have technical requirements like aircraft, but because they fly very low, they're also affected by sea conditions, and if it's too rough, can't operate.
I don't know if some kind of hydrofoil service might work, as they've been successfully commercialised, although they're still complex craft, and river use would probably require retractable foils which would add cost and complexity.