Probably the biggest use-case for those ships is as cable ships; there's always a mad dash to charter them when there's a bad cable break. A few years ago, when there was an earthquake at sea in the straits between Taiwan and Okinawa which took out multiple cable systems, there were something like 6 vessels on station at once, and a lot of people hoping nothing else broke for a while.
The two biggest operators are Alcatel and Global Marine Services of London. Which should make the usual suspects wet themselves all over again. didja no it a FRENSH airplane with LIMEY wings?