At the head of the navy is the Praefectus Classis.
Only the Senate may commission ships. The most common type of ship is the Trireme. A Trireme requires one Magister Navis and two Marines for service.
Praefectus Classis
The Praefectus Classis is the admiral of a fleet of ships.
Magister Navis
The Magister Navis is the captain of a ship.
Classis
The Classis is the ordinary marine and often the rower of a ship.