Coming up are the LARGEST ships on Earth!

 Many of the really big ships have pivoting propeller systems at the stern and horizontally mounted propellers in the bow to maneuver.  As far as cranes, when I lived in Osaka, taking the train to Kobe goes along Osaka Bay and I remember seeing these super-massive floating cranes.  To this day I wonder what kind of physics magic they use to stay afloat while lifting such monumental loads.  Hats off to the engineers that make life so amazing.  The company I worked for had the Seawise Giant on charter loading oil at Sullom Voe in the Shetlands. It was so large that when a giant wave hit its side the entire dock moved.  Another fun fact about the Zumwalt class. The 2 railguns at the front (Yes they are railguns and not just your regular 127mm naval guns) doesnt have any ammunition. At $35,000 per shell, the US navy wasn't keen on spending such a huge amount on ammunition for a prototype gun.  Those "incredibly powerful 6,700 horse power thrusters" are puny by naval standards. The diesel engines built into large ships routinely prodouce well over a hundred thousand shp(shaft horse power).