I was just on a 444 and there's lots of room both on deck and in various storage areas for scuba gear. To contradict maytrix, I know many dive masters from various operations here in the Caribbean and not a single one of them has not done solo dives. I also dive solo - but never in a new location or one that might be classified as "difficult". Most of the sites in the BVI are easy dives with no great depth and no strong current, but you have to take the boat there for the one diver while the rest of the crew do something else... which will probably not work out.