Why boats float · Pulse Beat
A boat floats because water pushes up on it. This is Archimedes' principle: the upward force on an object in a fluid equals the weight of the fluid it pushes aside.
A boat floats because water pushes up on it. This is Archimedes' principle: the upward force on an object in a fluid equals the weight of the fluid it pushes aside.
A steel ball sinks because it is denser than water: the water it displaces weighs less than the ball. A steel ship floats because its hull is hollow and mostly air. Its average density, steel and air together, is less than water's, so it only has to sink until the water it displaces weighs as much as the whole ship.
That is why the waterline sits lower when a boat is loaded. Salt water is denser than fresh, so the same ship rides a little higher in the sea.
Floating is also about balance. The weight pulls down through the centre of gravity and the buoyant force pushes up through the centre of buoyancy. When the boat tilts, a stable design makes these two forces turn it back upright. The boat on the home page does the same: it settles back toward the surface under it like a mass on a spring.