Usually, the hull of a ship contains a large volume of air. Why?
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The shape of the ships hull causes the ship to displace (get rid of or remove from one place to another) a greater volume of water then a solid piece of steel (or metal whichever the ship is made of) with the same mass. A ship displaces a volume of water equal in weight to the submerged portion of the ship, ok.in other words The air reduces the ships overall density so it can float!hope this helps!