What is Porpoising on a Jet Ski? How do you Stop it? [Video]
Porpoising is an undesired motion that happens when the bow of a jet ski bounces up and down on the water. It can be reduced or even eliminated by improving your riding technique or upgrading the ski with some aftermarket parts like a ride plate, intake grate, extended jet nozzle, or sponsons.
If you want to find out more about the topic this post is for you.
We at JetDrift have compiled all you need to know under one roof.
What is Jet Ski Porpoising?
Porpoising, also known as “bouncing,” is an annoying behavior of jet skis. It’s the repetitive motion of the bow of the ski going up and down, even on calm waters. Porpoising is not only uncomfortable and annoying but it also reduces controllability, which can result in a fall or even an accident.
On top of that, the repetitive bouncing can cause various types of damage like cracks in the hull or even engine misalignment.
To avoid these issues, you may want to know why your jet ski is porpoising and how you can eliminate it.
Why Does a Jet Ski Porpoise?
It’s safe to say that the most common causes of a jet ski porpoising are as follows:
- Wrong riding technique
- Improper trim settings
- Choppy waters
- Uneven weight distribution
- Inadequate sponsons, ride plate, or intake grate
- Defective hull design
Let’s get down to the nitty-gritty and talk about how these problems can be solved!
How do You Stop Your Jet Ski from Porpoising?
The easiest way to reduce or eliminate porpoising on your jet ski is by improving your riding technique and setting the trim correctly. If these measures don’t help, you can try to balance your jet ski with some extra weight or a larger fuel tank. However, many riders claim that they can significantly reduce porpoising by installing an aftermarket ride plate, intake grate, or sponsons.
In the following, we will talk about all of these in detail:
Correct Your Riding Technique
There’s no question that the easiest way to stop porpoising on your jet ski is by polishing your riding style.
In most cases, the root cause of porpoising is that your weight is distributed too far back on the machine.
This position doesn’t put sufficient weight on the bow, which is the typical trigger for porpoising.
To avoid this, you should move your weight towards the front of the ski. If you ride a stand-up, move closer to the handle pole, and if you’re on a runabout just sit closer to the handlebars.
When it comes to race-style accelerations, you should move your feet towards the stern while forcing your upper body towards the bow.
This will help keep the bow down and reduce or even prevent porpoising.
Adjust the Trim
Improper trim settings are another leading cause of porpoising issues.
If your jet ski features an adjustable trim system, set it all the way down at the starts or when the ski begins porpoising.
Setting the trim down causes the jet nozzle to shoot the water jet slightly downwards, which forces the bow into the water.
Once you’ve reached your desired speed, you can try to carefully set the trim up until porpoising starts. This means that you have to find the trim’s “sweet spot,” which requires some practice.
Also, you should keep the trim all the way down on a buoy race or when you just want to make some aggressive turns.
Keeping the trim down not only prevents porpoising but also ensures much sharper turns.
Porpoising is closely related to water conditions. As a rule of thumb, the bigger the chop the more the jet ski tends to porpoise.
This is no surprise since the waves act like little ramps, which start raising the jet ski’s bow. In many cases, this motion translates into porpoising.
The behavior of a jet ski is strongly dependent on its hull design. Most of them only start to porpoise in choppy water conditions, while a few others even do it on flat water.
If porpoising is a constant problem on your ski you should primarily ride on flat water. If you have to ride on the chop, try reducing your speed since this can reduce the extent of porpoising.
Improve Weight Distribution
If the aforementioned tricks don’t help, you have to dig deeper to fix the issue.
If the porpoising is caused by uneven weight distribution, you can fix it by adding some weight to the ski.
But let’s face it, carrying some unnecessary weight on the ski doesn’t seem like a good idea.
This is where larger fuel tanks come into play. The fuel tank on a jet ski is not only quite heavy when fully loaded but it’s also nestled in the front portion of the hull.
Therefore, a larger tank puts more weight into the bow of the ski.
What’s more, increasing the size of the fuel tank will not only change your jet ski’s weight distribution but it also allows you to cover longer distances.
Best practice is to experiment with some extra weights planted around the tank. If this helps to reduce the porpoising, you may want to remove the weights and replace the fuel tank with a bigger one.
Just make sure to wrap them in soft material and wedge them carefully in the storage bin so they don’t bounce around.
Sure, this trick only works on sit-down jet skis, so on a stand-up your only options would be a larger tank or some extra weight in the bow.
Porpoising can also be significantly reduced or even eliminated with some aftermarket mods.
The four most commonly upgraded parts are the ride plate, intake grate, jet nozzle, and sponsons.
Aftermarket ride plates are typically longer than their stock equivalents, so they protrude out farther toward the stern of the hull.
This little extension makes the hull slightly longer, which helps keep the bow down.
Unfortunately, these extended ride plates typically only fit on jet skis without a reverse system. This is because the reverse bucket typically doesn’t leave room for a longer ride plate.
Another trick is to install an aftermarket intake grate, which ensures a better hook-up, which virtually “glues” the hull to the water more.
When it comes to fixing porpoising issues, sponsons are often overlooked.
Special aftermarket sponsons can also lift the rear of the hull while pushing the front down. The performance of the sponsons strongly depends on their shape and angle.
If the aforementioned mods don’t help, your other option could be installing an extended jet nozzle.
You may wonder, which aftermarket parts should you choose for your ski?
Well, this cannot be answered easily since jet skis and aftermarket parts vary from one model to the next.
Best practice is to do your research on online PWC forums or ask a professional for help.
Last but not least, don’t forget that how prone a jet ski is to porpoising heavily depends on its features like dimensions, weight, and hull design.
General wisdom says that the lighter and smaller a jet ski the more likely it is to porpoise. In contrast, a heavy 3-seater runabout with a deep-V hull design runs much smoother.
This is why porpoising was much more common on stand-ups and vintage 2-stroke sit-downs. Those skis were very small and lightweight, so they were very sensitive to proper weight distribution.
Therefore, if you are looking for a more stable ski, you should invest in a 4-stroke, 3-seater runabout, featuring a heavy, deep-V hull.
The lively vintage 2-strokes are sure fun to ride, but they also tend to act like bucking horses.
Surprisingly, porpoising is not uncommon on some of the latest models either. As an example, the tiny Sea-Doo Spark can also porpoise under certain circumstances.
Porpoising on a jet ski is an undesired motion that causes the bow of the ski to bounce up and down on the water. It can be very annoying or even dangerous for you and your ski.
This is why you should eliminate it, as much as possible.
In a nutshell, the best ways to stop your jet ski from porpoising are as follows:
- Develop your riding skills: make sure that you shift your weight toward the bow.
- Adjust the trim: set the trim all way down to force the bow of the ski towards the water.
- Avoid choppy waters: the higher the chop, the more likely your jet ski will porpoise.
- Improve weight distribution: try to place some weight into the bow of the ski. You can’t go wrong with a larger fuel tank or a metal jet ski anchor in the front storage compartment.
- Modify your ski: porpoising can often be eliminated by installing an aftermarket ride plate, intake grate, extended jet nozzle, or sponsons.
- Replace your ski: some jet skis are more prone to porpoising like stand-ups and smaller 2-seater jet skis. If you are looking for a stable ski, you should take a look at the heavy, 3-seater runabouts with a deep-V hull.
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