I can’t tell you the many times I’ve seen people run their jet skis in too shallow of water, or the many times people brought me a jet ski that just sucked something up.
To be fair, most people don’t know the dangers of running in shallow water (or ignore the warning signs on the water). No one really tells them, and the warning stickers on the jet skis are more about wearing neoprene shorts and what fuel to use. But out of all the problems someone will run into when owning a jet ski, sucking things up into the pump is the number one thing. And you suck up things because you operated in too shallow of water.
It’s so bad… that everyone will do it. I’ve done it, and I know better, but things happen. Since it’s not so clear, I feel the need to write a post on it. In this post, I’ll explain the dangers and what to do if you suck something up. I’ll also give you pointers so you don’t keep sucking up more debris into your jet pump.
You Need To Stay Above 3 Feet!
Believe it or not, but jet skis are NOT designed to drive in shallow water. The general rule is that you must stay above 3 feet of water (about waist height for many people).
A jet ski will float in a few inches of water, but when the engine is on, you run the risk of sucking stuff up in less than 3 feet of water. So I suggest you stay above that or go somewhere else.
Also, putting your machine into neutral won’t stop the impeller from sucking things up. Jet skis use a direct drive system, so if the engine is on, the impeller is moving and water is moving. (Jet skis don’t have a true neutral)
What Happens When Suck Things Up?
Now for the dangers of sucking things up because you ran your jet ski in shallow waters:
- The jet pump is thrashed.
- You damage the jet pump.
- Damage the driveshaft.
- Blows the engine.
Let’s cover each one in more detail.
1. The Jet Pump Is Thrashed
When you suck up debris, it’s the jet pump that takes the abuse.
Many jet skis have a wear ring for this exact reason, it’s to protect the jet pump from major damage and make fixing it easier. Though, a damaged wear ring means the jet ski may cavitate and not want to run right.
Depending on the debris, it could be nothing that damages the pump. I’ve seen people suck up small sticks that cause issues but –eventually– break free and no more problems.
On the other hand, I’ve seen rocks get sucked up and destroy the impeller and wear ring. I’ve even seen some blow out the intake grate, which is designed to stop large objects (like rocks) from being sucked in.
Either way – your jet ski will be out of commission and needing repairs. What sucks is that many repair shops get backed up because people only ride in the summer months, and they all come at once. So you will often have to wait weeks to get it fixed, unless you do it yourself. I wouldn’t say it’s easy, and you may need special tools, but there are many YouTube videos showing how it’s done. If you’ve never used a wrench before, I would let the dealership do it.
2. You Damage The Reverse Bucket
Things that get sucked up into a jet ski will exit out the pump and sometimes the reverse bucket is in the way.
Jet skis don’t have transmissions and the forward, neutral and reverse is handled by a bucket that redirects the thrust. Neutral is a spot between forward and reverse, that is why it won’t help if you’re in shallow water.
If an object is large enough, it will get ejected by the powerful jet pump and smash into your reverse bucket. I’ve seen sticks and rocks get lodged in the arms of the bucket, causing people to lose forward or reverse functions.
3. Damaged Drive Shaft
This is more of a problem for older 2-stroke jet skis (and smaller engine watercraft like the Spark), but if you suck something up can stop the engine, and it could bend the driveshaft.
As covered, jet skis are direct drive, the engine is connected right to the impeller with a driveshaft. With enough force, you can stop the impeller and the engine, and all that energy needs to end up somewhere, so the drive shaft gets bent.
This will cause all kinds of running issues and cause the craft to shake. The only fix is replacing the driveshaft.
4-strokes have larger driveshafts as they’re bigger and more powerful engines, so the problem is not as common, but still possible. It sucks more on a 4-stroke if it gets the slightest bend in the driveshaft, as it can rub the carbon seal wrong and make your jet ski sink. Or the force is so strong that it knocks the alignment of the driveshaft and engine off and wears the carbon ring.
4. Blows The Engine
The most scary thing that can happen is you blow the engine. This is quite rare when sucking something up, and often something else was wrong and this was the straw that broke the camel’s back.
Being a direct drive system means anything that stops the impeller, like sucking up a rock that gets wedge between the impeller and wear ring, can be a lot of force. That force is carried from the driveshaft to the engine and if done right will “destroy parts of the engine”.
Luckily, there are a few “weaker parts” in line that should break before the engine blows a crank or anything else. But, sometimes you get unlucky and blow the engine.
How To Avoid Sucking Things Up?
It sounds kind of scary, blowing the engine is possible, but it’s not hard to avoid sucking things up.
You just need to be aware of where you ride. (And when, avoid riding after heavy rainstorms)
Don’t start your engine in no less than 3 feet of water. One trick I do is put my foot on the reboarding ladder and push off to deeper waters before starting the engine. For most people, 3 feet is about “waist height”, so you have something to reference: no need to bring a yard stick.
When beaching, I suggest you turn the engine off before you see land. It’s better to coast in or anchor out in the water with a screw anchor or tie off to a tree.
Avoid shallow-markers that many lakes have and know when the water level is down for your area. Where I live, you have the launches and websites that tell you the water level and what areas to avoid. The water level is up and down with the rain fall (or as the power plant near me needs it).