Jet Ski Propulsion

How a Jet Ski Works

For those of us that are not experienced with operating and maintaining watercraft, it may feel like a mystery as to how a Jet Ski actually works. If you aren’t mechanically inclined, you will want to have a basic understanding of the inner workings of a Jet Ski before you own one. It is essential that you have a basic understanding of the inner mechanical workings of your watercraft for proper maintenance and safety. Additionally, having a bit of background knowledge can help you make the right decisions should you need to hire someone to repair your Jet Ski. One of the most fundamental and important parts of a Jet Ski is its propulsion system, and you need to know how it works before you own one.

Jet Ski Propulsion Systems

Since a watercraft doesn’t have wheels, many people don’t understand the mechanics of how a Jet Ski is able to move through the water so quickly. Essentially, Jet Skis are powered by an internal combustion
engine that pushes water out of the rear of the watercraft to achieve movement. The following is a simplified explanation of how a Jet Ski propulsion system actually works:

Water enters a chamber that is located on the bottom of the watercraft through grating.
A gasoline engine provides the power to move the water. Often the engines are as powerful as the engine in a small car, and four-cylinder engines are pretty common.
The engine’s power is transferred to a water pump.
The water is pushed through a small hole called a nozzle located on the rear of the Jet Ski.
The nozzle can be turned to facilitate steering. When you push on the handlebars of your Jet Ski, a cable is pulled that directs the nozzle right or left.

Furthermore, some Jet Skis even have a mechanism called a reversing bucket. The reversing bucket directs the water stream forward, under the Jet Ski. This is helpful because it is the foundation of braking systems that help prevent colliding with other watercraft or stationary objects. These braking systems are extremely advantageous, but older models didn’t always have a braking system in the past. Fortunately, today’s Jet Skis are safer than ever before.

How the Water Jet Moves the Jet Ski

The driving physics principal behind the design of a Jet Ski’s propulsion system is Newton’s laws of motion. Newton’s third law states, “For every action there is an equal and opposite reaction.” This law describes why a rocket has the ability to launch and is fundamental to the engineering of Jet Skis. The jet of water that is being pushed out of the nozzle on your Jet Ski is a force that pushes against the relatively stationary water. In turn, the Jet Ski is propelled forward (the opposite reaction of the water jet). Having this basic understanding of a Jet Ski’s propulsion system is fundamental to operating them.