The Technology Behind Top Loader Intake Grates


So you want to gain more performance out of your personal watercraft but don’t want to break the bank. Well one of the easiest ways to do so is going to be to install a top loader intake grate. A relatively cheap item, this single part can help increase the performance, handling, and overall efficiency of your watercraft in terms of converting the output energy into usable thrust power.

So how exactly does the intake grate work and how can a top loader design improve performance? This article idea came from the folks at Australian Jetski Parts (AJSP) and we will try to touch on the basics of the technology and operating principles behind these flow devices.

The purpose of an intake grate is to gather the water and supply the pump with a constant uninterrupted stream of water. The pump then of course translates this stream of water into a massive flow rate gain. In other words, it gives us that awesome thrust.

If we break it down a bit further, the science of fluid mechanics states that pump flow rate is directly proportional to horsepower and inversely proportional to pump head. Okay, so the direct proportion to power is pretty self-explanatory.

We all know that if we have a more powerful engine that this generally means we can travel at higher speeds because the pump is able to flow water at a faster rate. So what about pump head? This topic is a bit more involved and we won’t go into too much detail for the purpose of this article but it has to do with the pressure difference across the pump and its capability to produce a measured lift of the fluid.

This means that when the pump head is large, the pump flow is low and instead creating high pressure on the exit side. While not an entirely accurate view, this phenomena can be somewhat visualized with a flyboard.

With a flyboard, the jet pump’s energy is being utilized not to create flow for watercraft movement, but instead to create lift (pump head) for the flyboard rider.

So what does all this mumbo jumbo have to do with intake grates? Well this flow rate equation in its simplest form always assumes a constant and steady supply of the fluid. As we riders know, this is not always the case.

We encounter waves, choppy water conditions, watercraft bow rise, and other real-world conditions that cause the intake grate to lose its “grip” or to scoop up and feed the pump less water. This causes a loss of thrust and a less efficient operation.

To help solve this problem, manufacturers and aftermarket suppliers have developed top loader intake grates. Top loader grates have additional scoops to gather and direct water flow upward to otherwise void areas of the pump.

This helps to fill the pump with more water and create more uniform thrust. It gives better performance and handling of your watercraft.

So are these top loaders worth the money? Many have asked the same question and as AJSP explains, they are an easy and cost effective bolt-on part which will give you instant results. In a nutshell, these grates are surely worth the money.

Just look at the manufacturers that are even now installing top loader grates on their factory watercraft. Yamaha’s GP1800R and VXR now come standard with these performance-enhancing items.

Yamaha states that “these performance enhancements provide sharper and more predictable handling with better hook up in rough water.”

This brings us to the next and final point of discussion. AJSP asked the question “Will it slow me down?” In other words, is the top loader grate meant for every rider in every condition?

Since these designs can have a larger surface area, it could mean that if you always ride in a straight line on nothing but calm water, then you wouldn’t notice a performance increase. On the other hand if you are like most folks, you not only ride straight but you change directions and maneuver your craft through sometimes choppy water.

These conditions favor the top loader intake grate. It will force more water through your pump and give you better hook up and overall performance.

The bottom line is, if you are serious about maximizing your watercraft’s performance, a top loader intake grate is one relatively inexpensive item that you should consider.

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Brice Leckrone

Brice Leckrone

Brice is a Mechanical Engineer for 33% of the day and a PWC enthusiast for 100% of the day. When he is not at work or at the farmhouse with his wife and countless animals, he likes to be on the water. Having evolved from motorcycles and race cars that go way too fast for a married man, he now likes to ride watercraft that go way too fast for a married man.

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