How do such large ships made of so much metal stay afloat?

Question

How do such large ships made of so much metal stay afloat?

Answer 1

Water displacement. And internal air.

Answer 2

By displacing water.

It turns out that the weight of the ship must equal the weight of the water displaced in order to stay afloat. The water would normally have to push up against the weight of the water above. Instead, it pushes up against the ship's hull when one is present.

When a ship takes on water, the amount of weight pushing down increases and eventually will cause the ship to sink

Answer 3

In very basic terms, what determines whether any thing floats (is supported by the water) or sinks in water is its density.  Density is how much the thing (whatever it is, it doesn't have to be a boat) weighs per volume, for example, so many pounds per cubic foot.  

If the density is less than water, (i.e. if it weighs less than its volume of water) it will float on top of the water.  That's called positive buoyancy.  

If the item has the same density as water (if it weighs the same as its volume of water), it will hang motionless in the water column, not going up or down.  That is called neutral buoyancy.  

If it has a greater density than water (if the item weighs more than its volume of water) it will sink.  That is called negative buoyancy.  

That's the reason big steel ships float.  It's because the entire weight of the ship is much less than its volume of water.  The amount of volume below the waterline is called the displacement.  That is because that's the amount of water the ship pushes out of the way due to its weight.  This value is variable, depending on how much the ship is loaded.  If you put on more cargo or equipment, the boat sinks lower in the water.  Naval architects calculate the displacement by calculating the amount of volume of the ship that's under the waterline and multiplying that value (in cubic feet in the united states, though we are slowly changing to metric) by the density of water, usually in pounds per cubic foot.  The density of water is different, btw, for salt water and fresh water, because salt water, at 64 pounds per cubic foot, is heavier than fresh water at 62.22 pounds per cubic foot.  So, it you have a boat in salt water that has 100 cubic feet of volume below the waterline, it has a displacement of 6400 pounds or 3.2 tons.  This is also how much the boat weighs if you were to hang it from a scale from a skyhook.

Now as for the 'parts' of the boat that provide support in the water, it is the hull of the ship or boat that actually contacts the water.  The hull has its own internal support that is made up of frames (the rib-looking things that the external shell of the hull is attached to), athwartship beams (the structual members that go from side to side), longitudinals (the structural members that go fore and aft) and stanchions (the structural members that go up and down that connect lower beams and longitudinals to upper beams and longitudinals.  All of these members are fastened together into one unified structure, so together they hold back the force of water pressure on the ships sides and bottom and keep the hull from collapsing.

This may be too involved an answer for the question you had in mind and if that's the case, I'm sorry for the epistle.

hope this cleared it up a little, good luck,

Answer 4

A mathmatical equasion called bouancy, the weight of gravity vs. the upward effect of the water as simple as can possibially be put

Answer 5

Because metal floats. Duh.