How does a boat operate?

The part of a boat that is under water has the same volume as the amount of water that weighs the same as the boat and everything in it. That is why a boat goes lower into the water whenever somebody boards. Propulsion is acheived by taking advantage of Newton's third law of motion: for every action there is an equal and opposite reaction. To move the boat in a certain direction, water is pushed in the opposite direction. Most boats use a propeller to push the water, but it can also be pushed by oars, a water wheel, a jet, etc.