2007-01-24 05:15:51 · 5 answers · asked by jwood 1 in Cars & Transportation ➔ Boats & Boating
Buoyancy.
Displacement refers to the volume of water the ship displaces (moves out of the way) or the weight of the water displaced - depending on context.
Buoyancy - as "discovered" by Archimedes is what actually makes the boat/ship float. This is the upward force applied by the water. (See the "trying to fill the void created when the ship displaces the water" description from a previous answer.)
The boat only displaces water equal to its weight. If you've taken a statics class this is easy to figure out. Forces have to be balanced or else the object moves until equilibrium is achieved. The weight of the vessel is equal to the weight of the water the hull is displacing. However the boat has reserve buoyancy - typically on a small boat that means that the vessel sits high enough in the water that adding extra weight (thereby lowering the boat in the water) does not cause the edges of the hull to sink dangerously close to the water level. In larger vessels there are water tight tanks, called ballast tanks, which can be filled with water or emptied to adjust the weight of the vessel. this maintains the displacement of the vessel even as it changes the weight of cargo it is carrying.
2007-01-24 08:43:13 · answer #1 · answered by Nika 2 · 2⤊ 1⤋
the boat displaces the water that would normally occupy that space with a less dense medium (air and wood). The water pressure wants to fill that void and so it pushes against surface and thereby keeps the boat at the surface as long as the boat does not sink below the freeboard level (in which case the pressure will be equalized and overcome very quickly).
More dense materials (a steel boat for example) must contain sufficient air or less dense materials to compensate for the greater mass. (Which is why bathtubs generally make poor boats - not enough air volume).
Some boats make use of this process by compressing the air and allowing water to fill the void. This makes the boat ride loweer or sink (we call them submarines). Then, by releasing the compressed air, they can force out the water ('blow the tanks'), change their internal density, and (hopefully) rise.
did that help a bit??
.
2007-01-24 05:24:10 · answer #2 · answered by ca_surveyor 7 · 1⤊ 2⤋
Displacement is the correct answer, but it has to displace much more than it weighs. If it displaced what it weighs it would barely float and could not carry anything else.
2007-01-24 05:25:51 · answer #3 · answered by mark t 7 · 1⤊ 1⤋
Displacement of water.
http://www.boatsafe.com/kids/021598kidsques.htm
2007-01-24 05:22:56 · answer #4 · answered by LondonGRL 3 · 2⤊ 0⤋
displacement
once it displaces an amount of water equal to its own weight, it floats. if it cant displace enough water, it sinks.
2007-01-24 05:22:02 · answer #5 · answered by Kutekymmee 6 · 1⤊ 0⤋