Most modern jet skis have a reverse feature that allows them to move backward. But the impeller does not reverse direction. Rather, there is a wide curved deflector (the bucket) that covers the jet nozzle and redirects water underneath the jet ski, causing to move backwards.
Contrary to what other sites or common sense might tell you, jet skis cannot reverse the direction of their impeller. In order to properly operate a jet ski, it’s important to know all of their features. One of the most useful features is the reverse function. I use it for docking regularly.
Riders should become familiar with operation of these functions to become safer and better riders. Let’s look at how a jet ski works and how a personal watercraft achieves its neutral and reverse features.
How does a jet ski work?
For the most part, a jet ski has an engine based similar to that of any motorized vehicle. That means that it has a piston-cylinder based engine that is placed underneath the seat of the jet ski. Modern skis use standard 4-stroke motors while some older skis are powered by 2-stroke engines.
When the jet ski is running, the torque from the engine is thrust directly onto a drive shaft that has an impeller attached towards the end of it. As the engine runs, the driveshaft is always rotating, and so does the impeller.
The shaft and impeller on PWC’s rotates only in one direction at all times (except for the newly introduced flushing system used to clear debris available on a limited number of Sea Doo models.)
How does the jet ski move forward?
Jet skis have water intakes positioned at the bottom or sides that allows the turning impeller to pull in water. No matter what design a jet ski has, the movement principle is the same. As the impeller starts to rotate, it sucks water through the bottom and pushes it out through a tube and out of the rear of the ski to move forward.
This strong intake of water is the main reason you shouldn’t run a jet ski in shallow water, since you could suck in debris and damage the pump or impeller.
The throttle controls the speed of impeller rotation which controls water flow, and thus determines the speed of travel of the jet ski.
The type of engine that a jet ski has is thus known as a direct drive system because the engine is connected directly to the impeller.
The water used to drive the ski is also used to cool the motor, impeller shaft, exhaust and other moving parts, at least in part. The engine’s heat is dissipated by the water flowing through the impeller tube, and the engine does not overheat.
Does a jet ski have a reverse gear?
Although a jet ski does not have a transmission that changes speed and direction of the impeller and shaft, it can still reverse or be placed in neutral.
How does a jet ski reverse work?
Situated at the back of the jet ski is what is called a steering nozzle. This nozzle directs the flow of water in a certain direction which is controlled by the handlebars.
The steering nozzle also controls the forward, neutral, and reverse of the jet ski. This controls all movement of the jet ski: forward, reverse, neutral and when turning.
When Reverse is activated, the curved steering bucket will fully cover the thrust nozzle, and it will actually be positioned in such a way that the water will be directed towards the bottom and front of the jet ski. This means that because the water is being thrust in a forward direction, so the jet ski will move in a backwards (reverse).
When the jet ski is placed in neutral, the bucket will cover the thrust nozzle and displace water flow in all directions, keeping the jet ski in one place while motor is running.
When a jet ski is running at idle speed, there is still some rotation of the impeller and shaft. So it cannot maintain its position unless the jet flow is controlled. Even though the flow is slow, it is still always there. Partially covering the output allows the ski to effectively be placed in neutral to keep positions steady.
Riders will need to be aware of a slight drift in motion that can occur while in neutral. When combined with wind and current, your ski may move around a little while in neutral.
Do all jet skis have reverse?
For the most part, most modern designed jet skis now come with reverse. However, It is important to note that older models and some models designed to be “stand up” jet skis do not come with reverse.
Why do jet skis have reverse?
When jet skis were first designed, the features of reverse were not included, and what you would need to do is turn around if you needed to go back to a particular location.
Reverse was introduced because of various safety reasons and for practicality. A lot of new jet ski owners aren’t aware that there is constant impeller rotation and jet flow even at idle speeds. They may continue to move towards an object. Being able to reverse can prevent a collision.
Another reason for the reverse feature is that it is much easier dock using reverse. Using neutral and reverse judiciously around docks makes them very controllable at slow speeds, and prevents unwanted scratches, scuffs and dents. You look like a pro once you’ve mastered the art of docking without having to grab anything, and it prevents hand injuries.
Conclusion
To summarize, jet skis have a reverse function that works differently than a car or boat. All movement and speed are controlled by a single water jet and a jet cover called the bucket. When reverse is activated, the bucket covers the nozzle forcing water to flow forward under the ski. That water flow pushes the jet ski backwards; it reverses the ski.
Jet skis also have a neutral feature that allows it to stay in place and brakes to stop quicker, all dependent on the jet nozzle and bucket covering it.
Keep in mind that older skis may have all, some or none of these functions. Make sure you know what your ski has and how to use it. Practice in open water away from other boaters until you get the hang of control.
Then you’ll be ready to dock like a Pro! Now get out there and have fun.
