Follow the explanation
Back to the model ↑How the parts work together
Follow the water in
Start at the grille below the shaft. The intake passage rises and turns toward the enclosed pump. Blue tracers mark the direction of entry; the full hull is omitted.
Spin, then straighten
The impeller rotates inside the casing and adds energy. Downstream stator vanes are fixed, so they guide the moving water without spinning with it.
Turn the jet
Move Steering nozzle to either side. The outlet, bucket hinge and outlet tracers pivot together. The fixed stator stays in the casing; this angle is not a calculated turning force.
Redirect for reverse
Lower Reversing bucket to 100%. Follow the tracers around the return duct and forward below the nozzle. The impeller keeps its original direction. Intermediate positions show gate motion only: the outlet cue is hidden because partial interception and neutral thrust are not simulated.
The main parts
- Intake
- The inlet admits surrounding water into the pump. Its grill and boundary shape are simplified here.
- Drive shaft
- An engine, omitted here, turns this shaft and the impeller together. A bored bearing housing supports the forward end; the shaft passes through the intake wall.
- Impeller
- Rotating blades transfer energy to the water. The blade count and shape are illustrative, not a performance design.
- Stator
- Fixed guide vanes reduce the impeller's swirl and guide the stream toward the nozzle.
- Steering nozzle
- The outlet pivots around its vertical pins. Its rounded seat and socket share the same steering centre. The blue tracers turn with the nozzle, not with the impeller.
- Reversing bucket
- The orange return duct hinges on the steering nozzle. Raised, it clears the outlet. Fully lowered, it catches the jet and curves it downward and forward. This original single-duct shape is not a replica of a production bucket.
Questions worth exploring
Does a jet boat reverse its impeller to go backward?
The reversing bucket changes the discharge direction while the impeller continues turning the same way. Fully raised, the bucket clears the jet. Fully lowered, it intercepts the discharge and redirects it forward. This model shows those two flow directions; during bucket travel it shows the hinge motion without predicting neutral thrust.
www.wartsila.comHamiltonJet · Stator function and reverse operation (page 4)American Turbine · Owner's manual: reverse-bucket endpoint coverage
What is the difference between the impeller and the stator?
The impeller rotates and transfers energy to the water. The stator stays fixed downstream, guiding the flow and recovering energy from its rotation. Open the cutaway and pause the model to compare the two blade assemblies. Their shapes are illustrative; the animation does not calculate pressure or swirl.
Wärtsilä · Waterjets and pump componentsHamiltonJet · Stator function and reverse operation (page 4)American Turbine · Owner's manual: reverse-bucket endpoint coverage
How does the steering nozzle turn the boat?
Pivoting the nozzle changes the direction of the discharged water and the resulting reaction on the boat. Here, the nozzle and its attached bucket pivot together while the pump remains fixed. The angle control demonstrates that relationship; it does not predict a turning radius or steering force.
Wärtsilä · Waterjets and pump componentsBerkeley Jet · Assembly components and nozzle-mounted reverse gate pivots