Astern propulsion

Astern propulsion is the ship manuver which the ships propulsion power is pushing it towards the stern (rear) of the boat. Astern propulsion does not nessassaraly mean the ship is moving towards stern (in reverse); it could simply mean the ship is slowing itself doesn by applying force in the opposite direction it's going.

A boat is required to signal it is opperating aster propulsion by either blowing three short blast on her blow horns or by waving the Sierra signal flag (white border with one central blue square).