I think Mr H says it all , Gone are the days when you worked from a supply boat with maybe only 2 levels , Now days your looking at 10 levels plus and , Your far better to have the control van sitting on I beams on deck as close to the vehicle as possible , I am sure all you guys reading this will have had in the past had a Lim problem just think if your control van was up on the bridge 10 levels up , Plus if your control van is on deck you can watch a movie and hide from the client .
I fully understand however that many work class vehicles are built into the vessel and you have no choice but for just a short term project best have the van on deck with your system with nice short cable runs , Then you only have to run a few cables to the bridge like comms , survey , video and your traffic lights .