When you say 'small cabin' I'm assuming you have an inside cabin. My wife and I dove Aca and P.V. on a Mexican west coast cruise and Coz on a W. Carr. cruise. In prep for the cruises, I visited
www.cruisecritic.com often. I never saw or heard of an area on the ship to dry your gear. The best we could do was rinse at one of the diveshops before coming back to the ship. Our room on the first cruise did in fact smell like a locker room after the second day of diving.
My advice: Woollite or wetsuit cleaner for lycra & wetsuits; take hangers for your BC/wetsuits; if someone you know has a balcony, beg them to borrow some space the evenings after your dives.
My real advice: If you can, leave your wetsuits at home. Perhaps take just the lycra bodysuits. It is the neoprene that will take forever to dry and will end up stinking up your room. Lysol & air freshener for your water shoes or boots if you have a chance to stop by a wal-greens on the way to the ship (btw, we took soda and water on the ship (Carnival & NCL) we bought while transfering to the ship.
Cruise advice: Buy a $6.00 clear plastic over-the-door 'shoe organizer',
similar to this one, but all clear plastic and costs $6.00.
The shoe organizer goes in your bathroom, hung probably from the towel rack, and you can put your shaving cream, hair brushes, hair spray, deoderant, etc. etc. in the pockets freeing up the limited sink space. Trust me, your travel companions will think you are a genius.
Also, we bought a duffle bag at Wal-Mart for $28 that has a seperate zipped compartment *for fins*. The bag doesn't look like anything special so it is less likely to get boosted if it has all your gear in it.
Enjoy!