The other day my friend Kully asked me what the biggest ships were. We had been watching a documentary called "Carrier", about life on board an aircraft carrier. I mentioned that the largest ships afloat are actually oil tankers, the largest ever being built in 1979 in Japan. Originally named the "Seawise Giant", she was 1504 ft long and could carry over 500,000 tons! To put that in perspective the empire state building is 1454 ft tall. By comparison the US carrier Nimitz is only 1092 feet. Anyway, They are powered by diesel engines, unlike the carriers which are nuclear powered. Here is a pic of the bottom end of one of these massive engines. Bore and stroke can be as large as 3 feet by 9 feet. That is big enough for a couple of people to ride up and down inside!