Jet ski

Jet boats and jet skis take their name from their propulsion system: the jet drive. They are not driven by a propeller but by a nozzle. Similar to aircraft jets, only using water as the medium. Water is drawn in through an intake in the bottom of the hull and expelled aft through a narrowing nozzle. As a result, going astern in a jet ski or jet boat does not work the same way as with conventional propeller drives. Because the flow direction cannot be reversed, a curved flap is used to redirect the jet and create reverse thrust. Advantages of jet skis and jet boats include their shallow draft and the fact that there is no propeller to damage.