For goodness sakes, I can tell a hire boat from a private boat any day. It has nothing to do with what anyone is wearing. We had our own boat for 10 years and we are still wearing the same clobber now that we are hiring , so that is a nonsense for a start. Most private boats tend to have a flag flapping at the back and often many more flapping elsewhere. Also you get to know the boats that are about.
As for SOB , I guess yelling at people through a loud haler does give them something to occupy themselves with.