Been on many liveaboards and none had a safe and never had a problem. One time I had to leave a boat when my dive buddy got sick and all my gear, money, jewelry, clothes, cameras that were left on the boat in my room and when I picked it up over a week later, it was all there. I would not do this on a land based trip however and would use the in-room safes that are usually in the rooms or carry it with me in several places.