[quote=TheSecret]
if they were more captains with more ships then we will have trouble to interact with eachother, how about you are sub-captain or something like that?
[/quote]

If utilizing the Royal Navy as a standard than the rank you're looking for is [url=http://www.royalnavalmuseum.org/info_sheets_nav_rankings.htm]Commander[/url]. Or even just [First] Lieutenant.