What Does a Cavitation Plate Do? | Explained

A cavitation plate is usually mounted to the lower units of the boats to help increase performance. They act as a plane surface ensuring the boat gets on top faster. This plate helps reduce the drag on the boat, which in turn makes it easier to get up on top of the waves.

The cavitation plate is also beneficial in that it helps to create more lift for the boat. This added lift allows the boat to travel at a higher speed with less resistance from the water.

If you are looking to buy a new boat, this plate can help you get more usability and speed out of your investment.

It is a small addition that can make a big difference when you are out on the water. If you already have a boat, make sure to ask your dealer about adding a cavitation plate to your unit. You will be glad you did.

What Is the Cause of Cavitation in Boats?

Cavitation can be described as the formation of vapor bubbles in a liquid. So, why do boat propellers cavitate? What happens is as the boat propeller goes faster, the production of bubbles increases and that results in cavitation. This is because as the boat propeller turns, there is a low-pressure area created and so bubbles tend to form.

How Do I Know if My Boat Is Cavitating?

Knowing whether your boat is cavitating is not complicated. There are three different ways to check if the boat is cavitating.

First, listen to the noise of air bubbles coming out of your propeller shaft. If these bubbles can be heard, it means you are possibly experiencing cavitation.

Second, before turning off the engine run your hand along the surface of your propeller. You should feel some drag as the air bubbles pass the blades. If so, your boat is cavitating and needs some sort of adjustment to stop it from going forward.

Lastly, there is a simple test that you can perform on your propeller. Go to a quiet spot with slow-moving water and tie off a rope or dock line around your prop without the engine running.

Turn your prop (by hand) so that the blades are perpendicular to the water flow. Now, look for bubbles coming out of the blades and along the shaft. If you see bubbles, then cavitation is occurring.

Do Cavitation Plates Work?

Yes, they do. Once they are mounted to the lower unit, they help increase performance. Cavitation plates create a thin sheet of water between the plate and the rotating propeller.

This helps to keep the propeller cooler and also to increase the speed and power of the boat. They are especially helpful in boats that have an outboard motor.

Cavitation plates are a great way to enhance the performance of outboards, making them more efficient and effective. Installing them on an outboard is typically a simple process, involving minimal modifications and no drilling into the engine itself. The cavitation plates themselves are designed to sit securely and prevent any vibration or movement, keeping your outboard running smoothly and reliably.

Cavitation plates mount on your outboard motor help the boat to plane faster and get on step quicker. By improving the hydrodynamics of your outboard, you can enjoy a better-performing engine without making any modifications. Additionally, cavitation plates are designed to protect your outboard from damage by preventing cavitation.

Cavitation is caused by low-pressure areas in the water around your propeller, which can cause the blades to create a vacuum. This can lead to loss of thrust, vibration, and even propeller damage. Cavitation plates help to prevent this by directing water flow around the propeller, keeping it operating at peak efficiency.

This helps keep your boat in good working order throughout its lifetime. If you have an older boat, this is a great way to help regenerate some of your boat speed without having to purchase a new motor or hull.

If you’re looking for an easy way to improve the performance of your outboard motor, cavitation plates are a great option. They’re simple to install, require no modifications, and can help to prevent cavitation and propeller damage. Whether you’re looking for better performance or protection for your outboard, cavitation plates are a great choice.

Should a Cavitation Plate Be Underwater?

Yes, a cavitation plate must be in the water when the boat is running. The cavitation plate is what creates bubbles of gas when it comes in contact with the propeller blades. These bubbles do not interfere with the movement of the boat but instead prevent erosion.

Erosion can come about when there are nicks or scratches on a propeller blade which allow water to get into the small cracks and accumulate over time. This build-up will cause the blade to lose its shape and eventually it will need to be replaced.

If a cavitation plate is not in the water, it cannot create the bubbles that protect the propeller blade. Without these bubbles, the propeller blade would come in contact with the water and erode over time.

Where Should the Cavitation Plate Be on A Flat Bottom Boat?

The cavitation plate should be as far forward on a flat bottom boat as possible. This is because if it is too much to the stern, there will be turbulence behind it, and resistance from the bubbles will reduce the speed of the boat.

If it is too far back, then this will make water difficult to push through and thus reduce speed. Ideally, the cavitation plate should be placed just behind the propeller on a flat bottom boat. This will ensure that the propeller is pulling in clean water with minimal turbulence and resistance.

If you have any questions about where to place your cavitation plate, please consult with a professional boat builder. They will be able to help you find the best location for your specific boat and application.

What Is Anti-Cavitation?

Anti-cavitation is a method used to fight cavitation in valves when used under extreme pressure differentials and high-velocity flow conditions.

Anti-cavitation methods are used to keep valves operational under harsh conditions for extended periods without replacement or maintenance.

How High Should Cavitation Plate Be on Plane?

To mount the plate the right way, you need to raise the motor to the point where it is just below or equal to the height of the running plane of the keel about 0.75 inches.

Normally, engines that have short shafts are equipped with a propeller spacer which raises the entire engine and this becomes your reference point. You can also use a washer when the motor mount is too low.

Cavitation Plate vs Hydrofoil

Both a cavitation plate and a hydrofoil are types of marine propulsors. A cavitation plate consists of widely-spaced, angled posts that protrude above the surface while a hydrofoil is shaped like an airplane wing.

The two devices operate in different ways:

A cavitation plate forces water through small holes, entraining the water into an area of low pressure behind the device to generate thrust.

A hydrofoil uses lift, like an airplane wing, to move through the water rather than push it aside.

Both devices have their pros and cons:

A cavitation plate is simple to construct and relatively cheap, but it can only be used in calm water and is not very efficient.

A hydrofoil is more expensive to build, but can be used in rougher water and is much more efficient.

Which device is better depends on the application? For a small boat or watercraft, a cavitation plate is likely to be the better option. For a larger vessel, a hydrofoil is the better choice.


To sum it up, cavitation plates are important additions to any boat to help protect the propeller from damage. They should be placed as far forward on a flat bottom boat as possible, and just behind the propeller on a plane.