For the RP we currently use navy ranks as well.
Officer cadet-new recruits that need to finish basic training.
Ensign-your average officer.
Lieutenant-Junior-Elected by officer for promotion based on skill level. Must pass inspection by board of captains.
Lieutenant-promoted by captain after provining skills.
Lieutenant-Commander-elected by captain requires command level skills.
Commander-promoted by captain after probing they have command level skills in missions.
Captain-promoted by captains board.
Currently that's all the ranks. More info is in the handbooks on the RP pages of the wiki.
To Mankind
And the hope that the war against folly may someday be won, after all
Isaac Asimov