Jet Drives: An inboard engine or outboard motor that drives a pump with impellers. The water is discharged from the jet pump impellers at high pressure through a nozzle that propels the boat.

North America

A jet drive propels a jet of water from the back of the boat.  The jet drive draws the water from under the boat into a pump inside the boat, and then expels it through a nozzle at the stern.  Steering is accomplished by moving this nozzle to either side, or less commonly, by small gates on either side that direct the jet stream.  Because the jet boat relies on the flow of water through the nozzle for control, it is not possible to steer a conventional jet boat without the engine running.

To reverse a jet drive a deflector is lowered into the jet stream after it leaves the outlet nozzle. This deflector redirects thrust forces forward to provide reverse thrust.  Steering is still available with the reverse deflector lowered so the vessel will have full maneuverability.  With the deflector lowered about halfway into the jet stream, forward and reverse thrust is equal so the boat maintains a fixed position with steering still available to allow the vessel to turn on the spot.

English Terminology: inboard jet drives, outboard jet drive, jet pump, jet propulsion gasoline, petrol, diesel, carbureted, fuel injection, internal combustion

French Terminology: intérieur lecteurs jet, jet d'entraînement hors-bord, pompe à jet, l'essence de propulsion à jet, essence, diesel, l'injection de carburant à carburateur, à combustion interne

German Terminology: Innenbordmotoren Jet Antriebe, Außenborder Jet-Antrieb, Jet-Pumpe, Düsenantrieb Benzin, Benzin, Diesel, Vergaser, Einspritzung, Verbrennungsmotor

Spanish Terminology: unidades interiores del jet, propulsión a chorro fuera de borda, bombas de chorro, la gasolina de propulsión a reacción, gasolina, diesel, con carburador, inyección de combustible, de combustión interna