The construction shows how place can be created and saved at the same time and give also a much better overview for the master who ferries it back and fore, all in all,,pretty smart I would say

Hello Sam

It looks like they built a ferry and then thought oh **** we forgot somewhere to put the vehicles. so they place the ferry on top of a barge.
Very nice looking vessel thou.

Best Regards
Adrian

Amazing looking superstructure (everything that's above main deck) ..... unique design indeed !