Update to my post #1988. I have at last caught up with the friend on sailed on
The MSC World Europa last month, the ship has a FREE to use male only sauna located in the gym locker room, it is open 0600-2100. He reports that the facility was barley used - he only saw one other chap in there all week, who like my friend used it a break to get some peace & quiet on a ship fully loaded with 7000 passengers!