Why aren’t cruise ships top heavy?
Liberty of the Seas (left) and Radiance of the Seas (right) tower over a pier in Cozumel, Mexico.
Modern cruise ships are quite tall rising more than a hundred feet into the air. At the same time, the ship only extends 25 feet below the water. Yet, these ships do not over and turn turtle.
The reason is that cruise have a low center of gravity. As Captain Christopher Turner of Holland America’s Zuiderdam explained: “If you look around the ship, most of it is just empty space. All our weight - - our engines, our machinery, our fresh water tanks, our fuel tanks - - are all down below. Although we have about 8 meters under the sea and 50 meters above the sea, the center of gravity is right down at the bottom. Even burning the fuel does not make too much difference. It does not bring the center of gravity up too much.”
In addition, many modern cruise ships are built so that the structure of the upper parts of the ship is not as heavy as the structure of the lower part of the ship. Captain Herman Zini of Royal Caribbean’s Allure of the Seas noted: “The thickness of the hull at the waterline is much thicker than in the upper levels. At the top levels some of the things are aluminum [instead of steel].”
Because the center of gravity is at the bottom of the ship, the ship floats upright.
Cruise ship FAQs - - Why aren't cruise ships top heavy?