Here is a multi-unit photograph from 2004. It is the Black Marlin heavy lift ship with the Maersk Guardian on the deck, and alongside the both of them is the Maersk Helper I think sending some-one up to the rig, on the basket. So the crane on the rig on the ship is being used. It is curious that often oil rigs on board heavy lift ships have many people on them, usually carrying out repairs ready for the next job. Although I worked in the business for many years I still have no idea how this squares up with the regulations.

Photograph taken by Tony Poll back in 2004 in Brazil and posted here on 20th February 2017.