Centrifugal pumps are the heart of jet skis. They are responsible for creating the propulsive force needed to move the bike through the water. Without an efficient centrifugal pump, your jet ski will not be able to reach its full potential and you will miss out on the thrill and adrenaline of riding on the water.

In this post you will discover how a jet ski works and the importance of centrifugal pumps to propel this type of watercraft.

Why do jet skis squirt from the stern?

Jet skis do not have an inboard/outboard engine with a propeller like those found on a conventional ship. A jet ski is propelled by a jet propulsion system or jet pump.

The jet pump is a type of centrifugal pump. A centrifugal pump is a machine that uses centrifugal force to move liquids from one place to another.

Let’s see how it works:

  1. Draws water from outside the boat (also called water body) through an inlet at the bottom of the boat.
  2. It expels the water backwards through an outlet nozzle at the rear.
  3. A thrust force is created that propels the boat forward.

Jet skis have a movable jet nozzle located at the stern. The speed of the jet ski is controlled by a lever on the right side of the handlebars. When we accelerate, the nozzle moves upwards, and when we turn the handlebars the nozzle also turns in the same direction.

These motorbikes have a peculiarity, and that is that unlike road bikes, jet skis do not always have a braking system, so to brake you have to let off the throttle by releasing the lever little by little. However, some, such as the Sea-Doo, do.

The jet propulsion system is safer for shallow water as it does not have a propeller. Even so, you should always leave a minimum distance of 200 metres from the coast and 50 metres from other boats, and never enter bathing or anchoring areas.

What does a jet pump consist of?

The jet pump consists of several parts:

  • Pump casing: outer casing of a pump.
  • Motor: can be electric or combustion.
  • Wear ring: helps to reduce the clearance between the impeller and the casing.
  • Impeller: wheel with blades that is connected to the motor.
  • Impeller shaft: helps keep water inside the pump and prevents air from entering the system.
  • Bearing: reduces friction between moving components.
  • O-rings: prevent gas or fluid leaks.
  • Jet nozzle: directs and controls the flow of water propelling the boat, affecting the direction, pitch, speed and performance of the boat.

It is important to keep the water pump in good condition to keep the watercraft safe. Therefore, it should be cleaned regularly to prevent the build-up of algae and other debris, and its component parts should be inspected.

How does the motor of a jet pump work?

Jet skis have a key that must be connected to operate the motor. This key is attached with a rope to the waistcoat, so that in case the rider falls into the water the jet ski will stop.

The motor of a jet pump works by providing mechanical power to turn an impeller, which is located inside the pump housing. This engine can be either a 2-stroke or a 4-stroke engine.

The type of engine and its capacity will depend on the size of the water pump. The engine of a water pump can be powered by electricity, gasoline, diesel, natural gas or other fuel. Electric motors are typically used in small and medium-sized water pumps (electric pumps), while internal combustion engines are common in larger water pumps (motor pumps).


As you have seen, centrifugal pumps are particularly important for the operation of jet skis, but also for all kinds of applications: boiler feed, drainage, sewage disposal, etc.

At MAQMAR we are distributors of pumps from prestigious manufacturers such as Bombas Azcue, KSB Itur and Calpeda, among others. We can offer you centrifugal pumps such as self-priming pumps, submersible pumps, as well as screw pumps, dewatering pumps, etc. Do not hesitate to contact us to help you find what you need. Follow us in LinkedIn!