No it's an honorific. Like I said the Quaker was a 78 ton ketch, so her captain is a lieutenant.

The Navy would never have named a vessel Quaker, but hired and bought-in vessels often kept their existing names, unless there was already a vessel of that name in the Navy. Hence there was a hired cutter that became HMS Black Joke, a name that knowledgeable folkies will recognise as a Cotswold morris tune taken from a certain song that celebrates a particular part of the female anatomy.