Cruise Ships: How They Sail Skyscrapers Around the World [Scientific American Magazine]
Large cruise ships typically host 1,800 passengers or more, plus 800 staff. Remarkably, many of these massive structures--three football fields long and 14 stories high--can deftly turn on a dime, spin 360 degrees, even mosey sideways.For years big ship propulsion had a standard configuration: a propeller in the rear with a rudder behind it to steer. But increasingly, they are being equipped with an innovative propulsion system called the Azipod, made by ABB Oy in Finland. This gigantic electric motor and propeller hang underneath the back of the ship from a hefty swivel that allows the rig to rotate 360 degrees, driving the ship in any direction. Smaller bow thrusters, installed laterally under the waterline in the nose of the hull, help to push the boat from side to side near docks or obstructions. [More]