The cruise was great!
They moved us to the Mandalay because the YC needed quick dry dock repairs. The Mandalay had been scheduled to do a second season of Fox-tv's Love Cruise, which bombed and was cancelled, so the ship was available to take up the YC's schedule.
As to the Clothing Optional part, very few on board went au naturel, except for a couple old farts the first week, who insisted on pushing the barriers (showing up at the buffet, dragging private parts across the table - yuk). They were finally told (by crew and pax alike) to not show up anywhere near the dining room naked. Thank God.
The second week was also quite sparse in nudity on board.
Both weeks, however, when we were ashore at private/secluded beaches, most went skinny-dipping.
Overall it was quite the conservative group, with average ages around 45-50, with very few under 30 (at least physically. Many were VERY young mentally - & fun).
Had a great time and crew were super - will definitely go again.
The 2 weeks after us was a straight nudist (as opposed to clothing-optional) cruise, with fairly mandatory constant nudity on & off ship - or so I heard...