MSC Cruises has announced four new ships that are to hold a record-breaking 6,850 passengers.
The World Class liners will eclipse the current holder of the world’s biggest cruise ship title.
Royal Caribbean’s Harmony of the Seas is the largest on the ocean, at a staggering 227,000 tonnes.
It can fit 6,780 passengers, boasting an ice-skating rink and a movie theatre on board.
So why do ocean giants like this stay afloat on the water when a tiny stone would sink to the bottom in an instant?
The answer lies in the fundamental scientific principles of buoyancy and density.
Cruise ships and other large vessels will float if they displace an amount of water equal to their mass.
As the ship moves forward, the water it pushes out of the way constantly tries to fill the gap.
It’s this energy, from buoyant force, that keeps the ship above the surface.
The ship’s hull is crucial to this principle. Usually very wide with a deep base line, the hull effectively pushes water out of the way to keep the boat afloat.
But buoyant force isn’t the only factor involved in keeping the vessel up.
The average density of the ship includes both the weight of the vessel and the empty spaces of air on board.
This must be less than the average density of the water, which thankfully in the open ocean is very dense.
So dense is the body of water in fact that a giant cruise ship is light as a feather on its vast surface.
In order to ensure the ship’s density is in proportion, engineers closely monitor the amount of open space on board. There must be ample air to keep the vessel afloat.
An analogy to demonstrate this is to think about a bowling ball being dropped into the ocean as compared to a beach ball.
Because the beach ball is filled with air, it would float on the water’s surface.
Due to the density of the bowling ball, it would sink to the bottom instantly.
Ships are specially designed with lightweight, stable materials to evenly disperse the weight.
