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What is Ultrasonic Anti-fouling?

An Ultrasonic Antifouling system is a “must have” for everyone who has their boat in the water. Our systems are cost-effective units that prevent bio-fouling from attaching to your hull. Less haul-outs saves valuable time and money. Our ultrasonic antifouling systems work on every type of boat including: V-Hull, pontoon, power cat, sailing, yacht, & commercial vessels.

In this section we will explain the process.


Marine Fouling & Anti-Fouling Technologies

Fouling is the process of marine organisms attaching and growing on surfaces below the waterline.

The most common method to fight back against fouling is the use of bottom paint.

Bottom paints and bottom coatings are available in a variety of formulations to help slow fouling. These bottom paints can include combinations of toxins, chemicals, and mechanical properties – the purpose is to prevent marine organisms from attaching to your underwater surfaces.

Bottom paint alone is not a very effective method of stopping marine fouling. Most all boats which are kept in the water must be routinely cleaned to remove the excessive fouling, with the bottom paint most effectively just providing an easily cleanable surface, protecting the hull from damage created by fouling and abrasive cleaners.

Ultrasonic antifouling provides much more prevention when compared to bottom paint alone. 

When ultrasonic antifouling is combined with bottom paint, a more effective solution is achieved, with the ultrasonic effect providing long periods between needed bottom cleaning, while the bottom paint provides physical protection of the hull and an easier, less damaging, cleaning experience.

Effects of Ultrasonic Stimulation

Ultrasounds are frequencies above that which can be heard or perceived by people. Ultrasound equipment is a large part of our daily lives and includes devices such vehicle parking sensors, ultrasound imaging in hospitals, and sonar on boats.


Just as the frequency of light can produce a wide variety of phenomena  such as radio, visible light, and microwaves, the same is true for sound – different frequencies will produce diverse effects ranging from imaging, communication signals, and mechanical vibration.

Different frequencies affect marine fouling in different ways. Ultrasounds between 20kHz and 40kHz produces a high pressure barrier along a surface. This microscopic barrier is only a few microns thick. Small organisms cannot occupy this high pressure space and are prevented from attaching, and repelled, from the surface.

Other frequencies have a different type of function. At frequencies above 40kHz, the cellular structure of fouling organisms that have attached  to the surface begins to be effected. Common tasks related to organism life processes and reproduction cycles are disrupted within this frequency range.

Ultrasonic antifouling achieves a cleaner hull and running gear in two ways. First, by preventing new fouling from attaching to the protected surfaces. The second function is the disruption of fouling organisms ability to reproduce and spread across the protected surfaces. It’s important to remember that an ultrasonic anti-fouling system will not reverse existing fouling that was present on the hull prior to the system being installed – the effects of ultrasonic antifouling are  preventative.


Implementation of Ultrasonic Antifouling

Unlike audible sound waves which can travel great distances through the air, ultrasound is most effectively transmitted through dense rigid surfaces. Consider ground penetrating radar – ultrasound can be utilized to create mapped images of depths over 100 feet through solid rock. Likewise, the ultrasound produced  spreads through surfaces that are to be protected.

The system provides ultrasonic emitters which are bonded directly to the hull surface at evenly spaced intervals. These ultrasonic emitters transmit ultrasound into the hull and protected surfaces. The transmitters receive signals from a fully automatic control unit which is centrally located in the boat.

Even more information from Hull Shield.


Enjoy 24/7 anti-fouling protection with Hull Shield ultrasonic anti-fouling systems. Ultrasonic anti-fouling using the power of ultrasound to keep your hull and running gear clean and free of marine fouling.

Hull Shield technology has proven itself over and over again – providing years of reliable service for boaters, praised by happy customers the world over, and become the preferred choice for boaters wanting the absolute best anti-fouling solution available. Our systems offer a fully automatic solution that works around-the-clock to keep your boat clean so that you don’t have to.

Maintaining a clean hull dramatically increases performance, speed, and fuel efficiency. Keeping your hull clean with ultrasound also extends the life of your bottom paint. Layers of valuable paint are removed every time the hull is scrubbed or power-washed – using Hull Shield stops this destructive routine cycle. You will enjoy significantly less maintenance costs, haul-outs, and extended paint life – all while having confidence that your boat will be operating at peak performance and efficiency.

HD Series

As part of the new HD series, the HD provides antifouling protection for hulls, drives, and other parts of a vessel that are prone to marine fouling.  The HD series offers an increased efficiency profile that is capable of delivering nearly double the power directly to the transducers when compared to prior versions. Additionally, all HD series products feature our latest hardware technology that boosts overall effectiveness by utilizing a higher frequency bandwidth. HD series products also provide more than twice as many frequencies and ultrasound bursts in targeted ranges.

The HD is a four transducer unit engineered as a stand-alone system which can be used to add antifouling protection to hulls, drives, rudders, stabilizers, and more. When used alone, it can provide ultrasonic antifouling protection for hulls up to 50ft in length, or a combination of 2 drives and 2 rudders when used for drives and stern gear. As with all Hull Shield products, the HD can be supplemented with additional systems to provide effective protection for vessels of any size.

Drives, Rudders, & More

Not just for hulls – Hull Shield can protect your drives and running gear too! Drives are isolated from the hull by motor mounts, gaskets, seals and other insulative materials that block ultrasound from passing to shafts, props, and rudders. Because of this, the drive system requires dedicated transducers to gain the most benefit from ultrasonic anti-fouling. Inboards, pods, sterndrives, and sail-drives can all be fitted with a transducer to enable full anti-fouling protection. Rudders are isolated from the hull in the same way as the drives and also require a dedicated transducer.

Hull Shield Antifouling Technology

Ultrasonic antifouling works by using sound waves to physically repel fouling organisms away from the surface before they can permanently attach. As a bonus, the higher frequency band of ultrasound also disrupts the reproductive cycles of certain types of bio-fouling.

Hull Shield systems operate similar to a stereo and speakers. The controller sends ultrasound signals to transducers attached to the hull or running gear, the transducers receive the high-frequency signals, transforming them into ultrasonic pulses.

Each pulse creates a microscopic shockwave that runs across the hull and drive gear. These ultrasonic waves work to ablate, loosen, and repel fouling which is contacting the hull and drive surfaces. When used in conjunction with an ablative bottom paint, Hull Shield systems are the most effective and long-term antifouling solution available.


The Hull Shield HD controller is the brain behind the brawn. HD controllers generate signals for up to 4 transducers and consume about 1Ah of current at maximum potential (when the battery system voltage is at or above 12.7V). The controller is mounted in an accessible location near the 12V battery system supply. The transducer signal cables are routed back to the controller. The HD enclosure is IP68 and NEMA rated for waterproof installation, and all connections are IP67 rated or above.

HD series controllers operate on 12VDC battery systems. Please contact us for alternate options on 24VDC systems.

1 or 4 Ultrasonic transducers

This system is equipped with four transducer emitters used to generate the ultrasonic signals which disrupt marine fouling.

Solar / Wind / Low-Power Mode

The HD controller is designed for optimum efficiency and ultrasound power delivery. The system is engineered to provide stable operation, even when powered from solar and wind supported power systems with fluctuating battery cycles. The controller will actively adjust the output power to match the current charge-state of the battery system – conserving power when necessary to preserve battery power and extend the length of time the system can operate.

The controller actively monitors system voltage levels which allows it to automatically enter  power conservation mode (PCM) when the system batteries are not being maintained. PCM is a completely automated process which reduces the average system power consumption to as low as 5 watts depending on available battery power.


This system features an automated sleep mode where it will automatically shut down to conserve system battery capacity for important tasks such as cranking motors and operating bilge pumps. The SLEEP MODE is activated when the HD detects that the battery voltage has dropped to 50% capacity (approximately 12.1V). When SLEEP MODE is activated, the Hull Shield halts all ultrasonic output and powers down; power consumption drops to near zero. The HD will automatically awaken when battery levels have returned to operational levels.



Each transducer provides approximately 200 sqft of protected underwater surface area. A rough estimate of your underwater surface area can be calculated by doubling your draft, adding it to your beam, and then multiplying by your LWL (length at the water line).


One transducer can provide dedicated protection for any single isolated part. Examples of isolated parts are drive shaft & props, rudders, exterior engine brackets, struts, swim platforms, and trim tabs. Because these parts are isolated from the hull and each other, a transducer is required for each isolated part.

Easy Installation

Hull Shield systems are simple in function and installation. Systems can be installed in a single day and require no technical skills. Besides the simple tools most customers have, everything required for an installation is included in with our products.

The Hull Shield controllers are best mounted in an accessible compartment. The transducers are simply attached directly to the surface of the hull or drive with the supplied 2-part epoxy.

Hull Shield transducers are waterproof and submersible. Transducers can be attached to the inside surface of the bilge, or externally on the transom.

Lifetime Warranty

All Hull Shield Ultrasonic products are fully covered under a Lifetime Warranty for the original purchaser. The warranty protects against defects in materials, workmanship, and parts issues.

Please Note: Hull Shield HD kits are provided with transducers having 15ft of attached cable. HD kits also include two 15ft signal cable extensions. Depending on boat size, you may require additional transducer signal cable to span the distance between the transducer mounting location and the controller. 

This unit can also be combined with other Hull Shield systems to extend protective range and/or antifouling intensity.

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