How Do Ships Float?


Science Out Loud. So if I take this box and just
obliterate it in the corner right here and then
put it in the water, the weight of the water rushing
in will cause the box to sink. If I take this box
and do the same thing, it tips over a little
bit, but it still floats. This box uses the
same kind of design that naval architects use
to prevent ships 1,000 times bigger from sinking. What’s so special
about this box that prevents it from sinking, even
with the big hole in its side? Let’s talk about why ships
sink in the first place. You probably know
that things will float in water if they’re
less dense than water and sink if they’re more dense. The metal that this
ship is made out of is way more dense than water, so
you might think it would sink. But that metal is
shaped so that it traps a lot of air, which
is less dense than water, inside it. So the average density
of the hull of the ship is actually much lower than that
of water, so the ship floats. But if the hull springs a
leak and fills up with water, there’s no more air to lower
the average density of the hull, so the ship sinks. The design of this box basically
prevents too much water from getting into it. This box’s hull was divided up
into watertight compartments with these walls
called bulkheads. So when I made a
hole right here, only this compartment
filled up with water. The rest stayed dry and were
able to keep the box afloat. This box is subdivided,
and so is this ship. Say this ship is divided into
ten watertight compartments. If one area of this
ship got damaged, only that compartment
would flood, but not any of the others. The added weight
of the water here would cause the ship
to tip over a little, to be angled or
trimmed in the water, but it wouldn’t completely
sink, and could still be taken to a port for repairs. So even with subdivision,
why do ships still sink? Well, it’s impractical
and expensive to design an unsinkable
ship, especially because most of the
time, ships just don’t see that much damage. What naval architects
do now is try to predict what kind of damage
is most likely to happen when designing a ship. Now, ships are more
complicated than this box. Naval architects have
to think about where to subdivide the ship,
the shape of the hull, and equipment that goes
into the compartments. We don’t know when people
first start subdividing ships, but the caps of
Chinese trade ships as far back as the
fifth century indicate that water would be
able to enter the vessel without causing it to sink. It’s pretty crazy that
technology that existed so long ago is still being used today. Hello, I’m Paul. Thank you for watching
Science Out Loud. For more information,
please visit our website. [LAUGHTER] See what they had me do?

89 thoughts on “How Do Ships Float?

  1. Hm. that was a pretty easy explaination. Because of the air within it. I knew that when I searched for this video mate.
    I thought there were some special tricks on why a shit doesn't sink.
    You could've at least told us how much air it takes to make like 100kgs of metal float and calculate that up to the size and weight of a ship.

  2. Actually im a naval architect . The air doesnnt make the ship float its about the buoyancy of the ship that makes it floating . The bulkheads are to prevent water from entering into the ship . there will be a collision bulkhead in the front to prevent the huge impact made from the collision . Actually there is no collision bulkead in titanic so it sank .

  3. All i can say is Great work to the Captains, Engineers and all the people that makes these things move. And Also the Builders, Spectacular piece of engineering.

  4. Before I searched this I thought under the ship was styrofoam😂😂

  5. Thank you for such an awesome video, we really liked it! We published it on our FB page with a credit to you 😉
    https://www.facebook.com/cruisebecom/videos/823707074457539/

  6. i have always asked myself when i was a little kid "why cant ships have a covered TOP ? like a submarine… " so that on stormy seas none of that water gets in.

  7. So we need 10 torpedo to get a ship. Im now thinking about MRL of torpedos take katyusha for ex. 😈😈😈😈😈😈

  8. Ships are so designed that when in water they displace a volume of water equal or less than its weight. A small nail will sink because it displaces more water than it's weight. Weight of ship and buoyancy or counter force from water.

  9. What if they sealed off the compartments horizontally has well that would help with the dip if a leak occured

  10. if we have a metal box and inside we have a ball and let them in water the box will sink but the ball will float or will sink also ?

  11. Nothing about displacement of water relative to load how about get a real engineer to explain then some nobody that knows shit about engineering Marvel's

  12. a cargo ship not sinking under its own weight is proof that gravity doesnt exist. its only density. Airplanes work on the same principle, that being DENSITY. weight is caused by density and gravity is fake

  13. Bad explanation.
    Air inside the hull ISN'T the reason it floats. You can float a solid needle on the top of water.

    If it was the air keeping it afloat, it would mean the ship would have to be airtight, and not have open doors and vents.

    Likewise, you could put a really heavy, but hollow, iron box in the water, and it could sink – air and all.

  14. thank you. how much money you have to put out keep your ship afloat ???? how much it cost ?>?? thank you okay show..

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