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How Shallow is Too Shallow – Avoid Damaging Your Jet Ski

I can’t tell you the many times I’ve seen people run their jet skis aground or damage the pump in too shallow of water.

To be fair, most owners don’t know the dangers of shallow waters (or ignore the warning signs on the water). No one really tells them, and the warning stickers on the craft are more about wearing neoprene shorts and what fuel to use. An important note to consider, out of all the problems someone will run into, sucking things up into the pump is the number one thing.

Therefore, for many new owners it brings up a good question, how shallow can you safely go?

In a nutshell, that is what I want to talk about in this post, so let’s dig in (or out if you’re stuck on a shoal)!

What depth is too shallow for jet skiing?

The great thing about jet skis is that they don’t have a low hanging, exposed prop that can hit things. But does this mean you can run safely in shallow waters, or will it be a problem?

A jet ski will float in a few inches of water, but you must stay above 3 feet when the engine is running.

Consequently, this is because the jet pump acts like a powerful vacuum that will suck up anything, like rocks and sticks, and that can jam the pump. A jammed pump keeps you from moving and ruins the weekend as you get it fixed.

Additionally, putting your jet ski into neutral won’t stop the impeller from sucking things up. This means Jet skis use a direct drive system, so if the engine is on, the impeller is moving and water is moving.

What Happens When You Suck Things Up?

I’ve got to cover it, but getting around excessively shallow waters is not without dangers to your PWC, or its jet pump. We’ve gathered a list of things that can happen if you’re not careful:

  1. The jet pump is thrashed.
  2. You damage the jet pump.
  3. Damage the driveshaft.
  4. Blows the engine.

Let’s cover each one in more detail.

1. The Jet Pump Is Thrashed

When you suck up debris when not staying above 3 feet, it’s the jet pump that takes the abuse.

Interesting to note, 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. In general, though, a damaged wear ring means the craft 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. Additionally, I’ve seen some blow out the intake grate, which is designed to stop large objects (like rocks) from being sucked in.

Either way – your craft will be out of commission and needing repairs. What sucks is that many repair shops get backed up because people are only out in the summer months, and they all come at once. As mentioned, you’ll 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. It’s mostly rocks that you see when you’re in shallow water that get sucked up that damage things.

It’s good to know that personal watercraft don’t have transmissions and the forward, neutral and reverse are handled by a bucket that redirects the thrust. Neutral on a PWC is a spot between forward and reverse, that is why it won’t help if you’re in shallow water.

Additionally, 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

From my understanding, 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. In low water areas and 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.

I’ve seen this cause all kinds of running issues and also cause the PWC 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 craft 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

I hate to say this, but a final point, the most scary thing that can happen is you blow the engine if you’re not careful operating in waters that are not deep. 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.

As already covered, 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. As you can assume, 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.

Sucking Things Up

Go ahead and take a breather, I know it sounds kind of scary, blowing the engine is possible, but a lot of this worry can be avoided if you only run the engine above 3 feet of water.

You just need to be aware of where you are. (And when, don’t go after a heavy rainstorms)

It’s vital that you don’t start your engine in no less than 3 feet water depth.

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.

Skip around 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 steer clear. The water level is up and down with the rain fall (or as the power plant near me needs it).

Conclusion

My rule for operating in shallow waters is to not go below 3 feet.

Everyone will have varied opinions, some say higher and some even saw lower. You’ll find the owner’s manual will say 2 to 4 feet, but it also depends on the speed you travel at or other debris under the craft. Either way, you’ll need 36 inches of clean water under you when idling around.

Author

Steven

I started working at a power sports dealership in 2007, I worked in parts, service counter, and as a technician before moving to sales in 2013. I created StevenInSales.com in 2014 to answer common watercraft questions I would get from people. Now managing the site full-time, I continue to provide advice and web tools for my readers about watercraft. I've owned several watercraft, with a Sea-Doo Spark as my current main PWC.

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