What makes ships float on water?

Question

What makes ships float on water?

Answer 1

the material and the holowness of the bottom.

Answer 2

simple answer - Mass displacement . If the Mass of water displaced by the boat hull, whether paper, plastic, fiberglass, metal, or cement ( yes, they actually MADE cement boats in WWII ! ) is greater than the mass of the entire boat itself DUE TO VOLUME, it will float. Water has weight, as does the boat. If the boat displaces less water by volume than it's own weight, then it sinks. It's truly a matter of volume displaced and the weight of that volume in tandem.

Look at it this way - if you take an oil tanker hull, and flatten the sides until they're only a few meters apart, you've saved some 40% metal weight, but you've DRASTICALLY reduced the amount of volume of water you're displacing, by many times. The boat hull won't have enough volume to stay above the water line, and will sink. If you expand the hull outwards and make it fatter, you've added that 40% of weight back, but you've also increased the amount of WATER you're displacing by 20  times ( don't know the real answer, it's hypothetical but somewhat close enough ) the volume , so the amount of water weight you're trying to displace is enormous. That's why steel and concrete ships can float, if you figure the internal volume right, that's filled with air and cargo, then the weight of the water for that many cubic feet, you can build your hull to match your load requirements.

- The Gremlin Guy -  

Answer 3

In high school we learned Archimedes Principal:  An object will float if the weight of the object equals the weight of the water it displaces. Test:  Weigh the object ( ship, boat, toy, etc.).  Take a rectangular aquarium tilted and filled with water to the point that anything placed in the aquarium will cause water to spill over the lower edge of the tank into a pitcher.  Put an object in the tank and after the water has stopped flowing -- weigh the water that was displaced.  If the weight of the water equals the weight of the object it will float.  If the weight of the object is greater than the weight of the water it displaced -- it will not float.  With regard to boats, ocean liners, etc., the principle applies.  In designing ocean liners, the amount of water displaced is based on the design of the hull, and numerous other calculations come into play to optimize speed, free-board, roll, etc.

Answer 4

Buoyancy  

Answer 5

Upthrust or buoyancy if you like.

Answer 6

Buoyancy is the upward force on an object produced by the surrounding liquid or gas in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object. The net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body. This force enables the object to float.

If you add too much weight, people or cargo, the boat will displace more water, freeboard will decease to zero (0) and the vessel will now sink.

An object, or boat, can displace water and still sink. A boat can have poor stability and still float, at least in calm waters

Answer 7

buoyancy, google for it