Since WW2 the Army trucks had a ring saddle mounted above the driver's cab. A Browning M2 0.5 inch (12.7 mm) machine gun is mounted on the ring, with 0.25 inch armor plates around the gun like an open turret. If mount this ring saddle turret on a wheeled cart it can travel on the ship main deck with the M2 machine gun. Hire some veteran guards and train the crew to support the security guards. M2 can reach the targets up to 800 m, 500 round ammo box in the cart, the pirates will become preys. 😎
