The Liberty Ship John W. Brown, an approximately 72 year old WWII troop and cargo steam ship, leaves the Baltimore Cruise Terminal. Ship requires tug boats when docking and undocking. Steam engine is running turning the single screw for power as it is assisted in power and directional control by the tug boat. Communication between ship and tug utilizes ships steam whistle and tugs whistle (modern devices are also used). Liberty Ships were critical in winning WWII and were built fast and cheaply in order to compensate for the massive ship losses to German U-boats.