How do big ships float?

If it displaces more water than it weighs, it will float. ¬¿¬

They displace water... The Buoyancy Principle Archimedes continued to do more experiments and came up with a buoyancy principle, that a ship will float when the weight of the water it displaces equals the weight of the ship and anything will float if it is shaped to displace its own weight of water before it reaches the point where it will submerge. This is kind of a technical way of looking at it. A ship that is launched sinks into the sea until the weight of the water it displaces is equal to its own weight. As the ship is loaded, it sinks deeper, displacing more water, and so the magnitude of the buoyant force continuously matches the weight of the ship and its cargo.

Gross tonnage is not a weight, it is a volume. It is equal to 100 cubic feet per gross registered ton.

They pump helium into the enormous hull and build a lot of the decking out of balsa wood and carbon fibre. Modern materials have enabled us to build ships 10x this size and still float. Look at icebergs for example.

Hi MJ, Your answers seem all OK, but I sometimes think of it in a more simplistic fashion. My tub, a steel built thing weighs around 8 tons when out of the water. When afloat it displaces about 12 tons of water. So it floats nicelywith a flotation lift of around 4 tons. Enough to keep the thing partially sunk to a depth, or draft, of around 2 and a bit feet. I have got it up an inlet near Northampton with more beer, musicians, and grub that shaking the proverbial stick at, a full deisel tank, a full fresh water tank, gas bottles, coal & logs on the roof for the pot-belly stove, all only just fitted aboard, and eventually grounded the thing in only 19 inches of water. So if it ever springs an alarming leak, and fills with water, I have lost the displacement, and gracefuly sink to the bottom. The Titanic syndrome. I shall be the last to leave the vessel as a matter of pride, and stand knee-deep on the roof, as canals are only about 6-8 ft deep. Same reason that helium party ballons go up. They displace a greater mass of air. My Dad & Uncle built a boat as young lads, which was fine apparantly until they both jumped aboard. The item could no longer displace enough water, so they sunk. A trial and error job. I shall keep on floating I hope ! Bob the Boat

A large ship floats by displacing the same weight in water as the weight of the ship.

once the hull displaced its mass in water it becomes boyant. hopefully, this is while the hull top is still above water. If thats true, the designer has done a good job. from there on in, its just plain sailing ( ha )

You need to understand two things, first water weighs 1kg per litre of water, second when they talk about a ships displacement they are talking about the amount of water the ship displaces when it is put into water. So long as the displacement figure is higher than the weight of the ship, then it will float.

Displacement theory. The weight of the ship pushes water out from around it, air inside the ship keeps id bouyant and the steel used to build it is thin enough to be of a density to keep it afloat.