Ships float, even if they are made of iron, because their overall density is less than that of the water that supports them. The water displaced by the hull of the ship pushes back upwards with a force called up thrust or buoyancy. If this is equal to or greater than the force of gravity pulling the ship’s mass downwards, the vessel will float. In fact, ships need a certain amount of weight to give them stability in the water, so many of them have hulls weighted with concrete or another kind of ballast. Without it, the ship would bob around on the water like a cork.
Not such a silly question! A ship or a boat (we’ll call them all boats from now on) is a vehicle that can float and move on the ocean, a river, or some other watery place, either through its own power or using power from the elements (wind, waves, or Sun). Most boats move partly through and partly above water but some (notably hovercraft and hydrofoils) lift up and speed over it while others (submarines and submersibles, which are small submarines) go entirely under it. These sound like quite pedantic distinctions, but they turn out to be very important—as we’ll see in a moment.
All boats can float, but floating is more complex and confusing than it sounds and its best discussed through a scientific concept called buoyancy, which is the force that causes floating. Any object will either float or sink in water depending on its density (how much a certain volume of it weighs). If it’s denser than water, it will usually sink; if it’s less dense, it will float. It doesn’t matter how big or small the object is: a gold ring will sink in water, while a piece of plastic as big as a football field will float. The basic rule is that an object will sink if it weighs more than exactly the same volume of water. But that doesn’t really explain why an aircraft carrier (made from dense metal) can float.
Picture Credit : Google