From the list of Enlisted Ratings in U.S. Navy
, we see that:
Captain's Clerk - Established 1798; disestablished 1835.
Not that this helps.
However, I think from something I read a couple of days ago (here - see the picture down the page
) that he would have a rank as chief warrant officer. In the army, at least, a warrant officer is referred to as Mr. So a Corporal Smith would be addressed as "Corporal Smith", Warrant Officer Smith as "Mr. Smith" and Colonel Smith as "Sir." You would not dare use "Sir" for a Warrant Officer!
Is that the same in the Navy? I don't know, but it makes sense.