What do Sponsons do on a Jet Ski? [Video]
Generally speaking, sponsons can improve the performance of a jet ski in many ways, but the most important of these are:
- Provide better traction to prevent the jet ski from drifting sideways while turning
- Ensures better and easier handling
- Improve stability
- Makes turns faster and sharper
- Lifts the hull at starts, which results in faster acceleration
- Helps reduce/eliminate porpoising
The sponsons on a jet ski are actually small fins that are mounted on both sides of the hull. They come in many shapes and materials but are most commonly made of plastic or metal.
If you want to discover the different types of sponsons and find out more about these key parts, you are in the right place.
We at JetDrift have gathered the basics of jet ski sponsons under one roof!
What is a Sponson on a Jet Ski?
To understand the importance of sponsons on a jet ski, let’s talk briefly about other vessels.
If you’ve ever checked a bottom of a sailboat, you probably noticed a huge blade that protrudes from the bottom of the hull.
This part is called the keel, which provides sideway resistance, so it prevents the vessel from drifting sideways.
Here’s a great video on how keels work on a sailboat.
For the same reason wakeboards, surfboards, and many other types of watersport equipment feature smaller fins or skegs.
Basically, all of these parts do the same job, they prevent the boards from drifting sideways or rotating on the surface of the water. The fins make them easier to control and also improve their directional stability.
But how does this relate to jet skis?
It is as simple as can be!
The sponsons on a jet ski work like the keel on sailboats or fins on wakeboards. They are metal or plastic fins that are bolted onto both sides of the hull. Sponsons grip the water, which results in better traction in the turns. Today many stock and aftermarket jet ski sponson are adjustable so you can customize them based on your riding style and experience.
The lower the sponsons the sharper the turns you can do with your jet ski!
But are you wondering how sponsons actually work and why they are mounted on the sides of the jet ski?
What Do Sponsons Do on a Jet Ski?
Simply put, when you aggressively turn your jet ski it actually leans like a motorcycle.
Because of this, at higher speeds, the jet ski turns on its side rather than on its bottom. But if you’ve ever taken a closer look at the side of the hull, you’ve probably noticed that it’s completely flat.
And turning on this flat surface would be very difficult as the momentum would force the jet ski sideways. Finally, it would cause the hull to drift and make turning more difficult.
The higher the speed the more likely the jet ski would be to slip sideways.
This is where the sponsons come into play!
As they are bolted on the sides of the jet ski, they increase the drag on the side of the hull.
In other words, the surface of the sponsons dig into the water like fins on wakeboards and surfboards.
So finally, what do sponsons exactly do on a jet ski?
Simply put, the sponsons on a jet ski improve traction in the turns. This means they prevent the jet ski from sliding sideways, which causes the machine to turn much faster and sharper. They also make handling much safer and easier. On top of that, sponsons help lift the hull during acceleration and can help eliminate porpoising as well.
That’s why today every new jet ski comes with sponsons as standard!
Sponsons are very important parts of any jet ski, as they make operating them safer.
Racers and performance-minded riders can also benefit from these fins, since they also help the jet ski to turn much faster.
It’s a lesser-known fact that the first jet ski sponsons were originally designed to reduce porpoising issues.
The first block sponsons were introduced on the Sea-Doo GT series at the end of the ‘80s. Although these early units increased hull stability and reduced porpoising, they surprisingly didn’t provide better handling.
But in 1993 Sea-Doo redesigned the sponsons, which came with a new “curved” design. These new sponsons provided better traction, which contributed to better handling as well.
Another key advantage of sponsons is that they can help lift the hull when you first start the machine.
These are great features because before you start, the hull sits completely in the water. When you hit the throttle, your jet ski has to first come to the surface of the water before it can reach higher speeds.
It takes time and a lot of energy!
But thanks to the angled sponson design, the jet ski can get to the surface much easier. Simply put, these angled jet ski sponsons work in the same way as the wings of planes.
They provide some lift, which helps the hull rise faster. The easier the jet ski reaches its planing speed the sooner it can start to develop more momentum.
Finally, this results in faster acceleration, and better gas mileage!
Jet Skis Without Sponsons
As you may assume, a jet ski without sponsons is very hard to handle, as it slides instead of turns in the corners. Therefore, it’s highly recommended that you never remove the sponsons from your jet ski!
Here’s what happens if you try to ride a jet ski without sponsons:
Aftermarket Jet Ski Sponson Kits
Although virtually every new jet ski comes with factory-fitted sponsons, you can choose from many great aftermarket kits as well.
Let’s take a closer look at them!
OEM vs. Aftermarket Jet Ski Sponsons
Keeping safety in mind, stock jet ski sponsons are typically designed for better handling and stability.
But if you want to race your jet ski or just want to make it turn more aggressively, you should consider investing in an aftermarket sponson kit.
These performance jet ski sponsons are designed to make your jet ski turn harder and much faster.
They are typically made of high-quality materials; hence, they are more durable.
What’s more, unlike their stock counterparts, performance sponsons are typically adjustable.
Jet Ski Front Sponsons
Besides regular “rear” sponsons there is a lesser-known type of sponson, which can be mounted on the front side of the hull.
These front jet ski sponsons are also known as jet ski tubbies and feature a larger and more curved design. They are primarily designed to increase the turning grip and lift rather than eliminate drifting issues. As in addition, they provide greater stability when the jet ski goes straight or in the turns as well.
If you would like to find out more about front jet ski sponsons, don’t miss this great video:
Homemade Jet Ski Sponsons
Let’s face it, jet ski sponsons are not cheap. Performance jet ski sponson kits cost about $150-$600 depending on the make and model!
But if you are on a budget the good news is that you can even make custom sponsons for your jet ski by yourself.
DIY jet ski sponsons are typically made of high-density plastic or even kitchen cutting boards. Cutting boards come in many shapes but most riders prefer to use boards 1/2 inch thick. You may want to make a pair of backing plates to support the inside of the hull. Never bolt the sponsons directly to the hull as it may damage its material!
The required size of the sponsons always depends on the type and performance of your machine.
You can get some ideas by checking stock and performance sponson kits!
Installing Jet Ski Sponsons
The main advantage of aftermarket sponsons is that they fit in place of the stock units.
Thanks to this, installing jet ski sponsons is very easy as you can simply bolt them to the hull without drilling new holes. However, be careful as you have to tighten the bolts properly. Also, you will likely have to apply some silicone to keep water away from the inside of the hull. Improper installation or poor sealing may end in water leaks, which can cause your jet ski to sink!
That’s why you have to make sure to read the installation manual and follow the manufacturer’s recommendation.
You have to pay double attention to the sealing especially if your jet ski was not previously equipped with sponsons. This is because you may have to drill holes into the hull!
However, on many stand-up jet skis the sponsons can be bolted directly onto the bumper.
This means the exact installation process always depends on the type of machine and the design of the sponsons.
If you would like to learn more, here’s a great tutorial on how to install jet ski sponsons:
Inflatable Jet Ski Sponsons
“Regular” jet ski sponsons and inflatable jet ski sponsons are often confused for each other; however, they are meant for completely different purposes.
As we’ve discussed, regular jet ski sponsons are basically hard plastic fins bolted onto the rear sides of the hull.
In contrast, inflatable jet ski sponsons are large inflatable collars designed to increase stability and buoyancy. This results in higher safety and carrying capacity. These special additions are actually two giant inflatable tubes that can be mounted to both sides of the jet ski.
Inflatable sponsons come in handy on jet ski fishing tours or when the jet ski is used for rescues!
Conclusion – Do Sponsons Make a Difference?
Jet ski sponsons are small plastic or metal fins mounted on both sides of the hull.
The most commonly used jet ski sponsons are “rear sponson,” which can be virtually found on any new jet ski regardless of type. In contrast, front sponsons are exclusively used on stand-up jet skis.
There’s no question that sponsons make a big difference in handling. A jet ski without these fins would slide out in the turns, which would result in less control and poor performance. Having sponsons on your craft ensures better handling and sharper turns. Besides, they can help the jet ski reach its planing speed faster and eliminate porpoising.
This is why sponsons are a must on every jet ski!
Disclaimer: This post is for general information purposes. Always check the installation manual before you install any new part on your ski!
DISCOVER 2023 PWC MODELS Kawasaki, Sea-Doo, Yamaha, Krash…