Air cannon

The combination of a ship with a stern and an air cannon for launching projectiles by high pressure air comprising a base attached to said ship, said air cannon movably mounted on said base, said cannon having a main chamber connected to one end of a barrel, a feed chamber connected to said main chamber, said feed chamber housing at least one projectile, a movable retaining pin mounted in said feed chamber and contacting said at least one projectile, a low pressure valve fluidly coupled to said pin, a movable breech block in said main chamber, said breech block having a high pressure side and a low pressure side, at least one high pressure valve fluidly coupled to said main chamber between said high pressure side of said breech block and said one end of said barrel, a projectile in said main chamber between said one end of said barrel and said high pressure valve, at least one low pressure valve fluidly coupled to said main chamber separated from said one end of said barrel by said low pressure side of said breech block, at least one exhaust valve fluidly coupled to said main chamber separated from said one end of said barrel by said breech block, a source of high pressure air fluidly connected to said low pressure valve and said high pressure valve by a low pressure line and a high pressure line, respectively, a regulator in said low pressure line to adjust said high pressure air, a controller for operating said valves, a trigger mounted on said main chamber and connected to said controller whereby actuation of said trigger starts a launch sequence and opens said high pressure valve admitting high pressure air to said high pressure side of said breech block and launching said projectile from said barrel, said breech block moving in said main chamber away from said one end of said barrel, said launch sequence opening said low pressure valve and moving said pin out of contact with said projectile in said feed chamber, said projectile in said feed chamber moving into said main chamber between said breech block and said one end of said barrel, said low pressure on said low pressure side of said breech block moving said breech block toward said one end of said barrel to provide repeated launchings of projectiles from said ship.