If the Brotherhood had a small navy, what branch/rank would be given to its sailors?

This is something that has been on my mind for a while now, the Lancers were created as their own separate branch to pilot the Brotherhood's vertibirds. But I've wondered what special branch/rank the Brotherhood would give if they had a small navy of ships.

Nothing too grand for a navy, maybe just a handful of salvaged and recovered ships from the US Navy and Coast Guard. Any ideas for a rank structure?