Why is My Sea-Doo Slow? The Truth About Cavitation & Wear Rings
You're out on the water, you squeeze the throttle on your Sea-Doo, the engine screams to high RPMs... but you're not going anywhere fast. It feels sluggish, struggles to get on plane, and your top speed is way down from what it used to be.
If this sounds familiar, you are almost certainly experiencing cavitation. This isn't an engine problem—it's a pump problem. And on a Sea-Doo, the #1 culprit is a damaged wear ring or impeller.
Watch Me Explain This on TikTok
It's much easier to understand when you can see the damage. I made a short TikTok video showing exactly what a worn-out wear ring and a damaged impeller look like from a customer's ski.
What is Cavitation?
In simple terms, cavitation is when your jet pump "sucks air" (or, more accurately, boils the water into vapor) instead of getting a clean "bite" of solid water.
Think of it like a car spinning its tires in mud. The engine is working hard, but the power isn't being transferred to the ground. On your jet ski, the engine is spinning the impeller, but a damaged pump can't grab the water to create thrust. The result? Lots of noise, not much speed.
The Two Parts That Cause This
Your jet pump is a high-powered, precision-built system. It only works if two key parts are in perfect condition:
The Impeller: This is the small, high-tech "impeller" located inside the jet pump. It spins at thousands of RPMs to grab water and shoot it out the back.
The Wear Ring (The Sea-Doo Secret): This is a sacrificial plastic ring that the impeller sits inside. Its entire job is to create a razor-thin, perfect seal around the outside of the impeller blades.
When these two parts are in good shape, 100% of the water sucked in is forced out the back at high pressure. This is your thrust.
How Does it Get Damaged?
Your jet ski is essentially a high-powered vacuum cleaner for the water. If you ride in shallow water or near a beach, it's very easy to suck up:
Sand
Small rocks or pebbles
Shells
A piece of rope or a plastic bag
When this debris gets sucked through the pump, it acts like a chisel. The rocks and shells will gouge the plastic wear ring and chip or bend the impeller.
This damage creates a gap between the impeller and the wear ring. Now, when the impeller spins, water slips back around the gap instead of being forced out the back. This loss of pressure is cavitation. Even a gap as small as a nickel's thickness can cause a massive loss of performance.
What are the Symptoms?
If your wear ring is bad, you will notice:
A "sluggish" or "spongy" feeling on acceleration.
The engine revs high, but the ski doesn't "hook up" and go.
A significant loss of top speed (e.g., your ski used to hit 60 MPH but now only hits 52).
Vibration from the back of the jet ski (if the impeller is bent).
How to Check It
You can do a quick check yourself. With the ski safely on a trailer, take a flashlight and look into the jet pump nozzle from the back. Look at the space between the impeller blades and the outer ring. Do you see big gaps? Do you see deep gouges or scratches in the plastic ring? If you do, you've found your problem.
This isn't a problem you can "live with." It will only get worse. The good news is that it's a very common and routine repair. At Odyssea, we replace wear rings and inspect impellers every single day. Bring it by, and we'll get that "holeshot" and top speed right back where it's supposed to be.
Call us at (410) 973-2890 or click below to schedule your service.
