The Basics of Jet Ski Engine Propulsion

The owner and manager of the National Restoration Group in New York City, Mohammad Riaz oversees all project acquisition and management operations for a range of specialized construction projects. When he isn’t working, Mohammad Riaz enjoys riding Jet Skis.

Jet Skis and similar personal watercraft come with either a two-stroke engine (which typically has two or three cylinders) or a four-stroke engine (which typically has four cylinders). Unlike the engines of terrestrial vehicles that require radiators, Jet Ski engines employ surrounding water for temperature control. 

To propel the Jet Ski, the engine turns a piece of equipment called an impeller. Located inside the body of the watercraft near the rear of its submerged bottom, the impeller features curved blades that are similar to those of propeller. While a propeller pushes water outward, the impeller takes water into the Jet Ski at a rapid rate. The water travels through a short internal channel to exit at an adjustable steering nozzle at the back of the watercraft, hitting the relatively stationary water outside with such force that it generates forward thrust. Most modern Jet Skis have reversible impellers that can also move the watercraft in a backward direction.