I've noticed that actual theft is pretty random and fairly rare. Nobody locks their dinghy for months and then all of a sudden one bad actor goes on a crime spree. Until they are caught ppl who are in the know (ie local) all lock their dinghys. A bigger problem is very drunk customers boarding your dinghy and borrowing it for a lift home at places like Foxys NYE or the Willie T.

My company had a very expensive RIB stolen in SXM a few years back and the local cops (who are spectacularly unhelpful) blamed it on organized crime or crooks from off island and did absolutely nothing to help. So don't expect much help if you are unlucky enough to lose your dinghy - I think this is a good reason to lock it up, since a charterer doesn't a prayer of getting it back if it is lost.

You don't have to be the most secure dinghy on the dock, but it helps if you are more secure than the guy beside you. I always take the key (or rather the hair band) when leaving to discourage drunk hop-ons at Foxy's, and lock the whole thing if I'm going far away or if my dinghy is one of the nicer ones on the dock. Most charter dinghys aren't worth stealing, but if you've got something longer that 10ft with more that 10hp it is worth taking the time so lock it.

Now if I could only find a way to keep confused drunk people from sleeping in my dinghy I would be all set.