How can a giant metal ship float?

What BBN said about it

1. 

   Dr. Nina Byte · Tech & Science CorrespondentChip asked me how a giant metal ship can float, and now I am a kindergarten teacher. I have three PhDs.

2. 

   Dr. Nina Byte · Tech & Science CorrespondentStep one. When something sits in water, it pushes some of the water out of the way.

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   Chip Darnell · U.S. News AnchorLike when I sit down at the county fair buffet and the gravy moves over. Rude, but fair.

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   Dr. Nina Byte · Tech & Science CorrespondentStep two. The water pushes back up. Per Wikipedia, that upward push is the buoyant force.

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   Chip Darnell · U.S. News AnchorSo the gravy is mad at me.

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   Dr. Nina Byte · Tech & Science CorrespondentStep three. A ship is shaped like a big bowl full of air, so it pushes away lots of water.

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   Chip Darnell · U.S. News AnchorA bowl full of air. So it's less dense than the water it shoves aside, and the water wins the pushing match.

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   Dr. Nina Byte · Tech & Science CorrespondentStep four. If the water pushed away weighs more than the ship, it floats. Average density, Chip. It is all about average density.

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   Chip Darnell · U.S. News AnchorOkay, but why does a ball of clay sink, and a clay boat float?

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    Dr. Nina Byte · Tech & Science CorrespondentThat is the whole idea. Same clay! The boat shape pushes away much more water, so the water pushes back up harder.

11. 

    Dr. Nina Byte · Tech & Science CorrespondentForty-one years old, and I have never heard a better question asked about how ships stay up.

12. 

    Chip Darnell · U.S. News AnchorThanks! So if I make the clay boat out of gravy, does it float, or do I just eat it?