I would always prefer AC but probably could be OK if we have a quality ceiling fan that puts out some serious CFM's.....
For me it's really the humidity that makes the difference. If it's a drier desert island.....like Bonaire.... with pretty much constant ocean breeze and not to "buggy" then I can acclimatize and be OK... But a liveboard with nothing but a non opening porthole has to have AC. Wherever I go in the tropics I always bring a small personal "clamp-on" fan so I can at least have some circulating air on my face while sleeping.
For me it's really the humidity that makes the difference. If it's a drier desert island.....like Bonaire.... with pretty much constant ocean breeze and not to "buggy" then I can acclimatize and be OK... But a liveboard with nothing but a non opening porthole has to have AC. Wherever I go in the tropics I always bring a small personal "clamp-on" fan so I can at least have some circulating air on my face while sleeping.