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The Sonihull ultrasonic antifouling system by NRG Marine uses the latest digital electronics and ultrasonic transducer technology. This system works by producing bursts of ultrasonic energy in multiple frequencies, the energy creates a pattern of alternating positive and negative pressure. Microscopic bubbles are created from the negative pressure, while the positive pressure implodes them forming vapor cavities known as cavitation. The result of the implosion is a micro jet action that creates a cleaning effect on the hulls surface below the waterline. It also resonates and destroys single cell organisms such as algae. Removing the initial link in the food chain prevents barnacles and other marine life to feed on the algae.

Sonihull Duo


For hundreds of years mariners have been plagued with the same old problem of marine growth on the hull, power train and steering gear for their yachts. With this comes:


Sonihull is a cost effective antifouling product that works alongside a conventional antifouling paint with additional benefits.

In addition to reducing annual haul out costs, Sonihull reduces growth on hull, stern gear, and bow thrusters. A clean hull will substantially reduce fuel costs while keeping the boat performing as it should.


After Sonihull’s arrival in the market place many Manufacturers have tried to introduce competing products. However Sonihull continues to deliver the best product quality and features available in any Ultrasonic Antifouling System.


Sonihull systems produce multiple bursts of ultrasonic energy in a range of targeted ultrasonic pulse frequencies. This produces a pattern of alternating positive and negative pressure, whereby the microscopic bubbles that are created during the negative pressure are imploded when positive pressure is applied.

How the Sonihull System works

The implosion has a cleansing effect that destroys algae, the first link of the food chain, making the surface less attractive to other marine life that feed on the algae. This microscopic movement of water also prevents barnacle and mussel larvae from embedding.

Sonihull works on GRP, composite, aluminum, steel or carbon hull material, but not on wood.


Reduce your carbon footprint!

With new environmental regulations set to substantially reduce the effectiveness of traditional antifouling paints, PYI Inc. offers Sonihull Ultrasonic Antifouling Systems as a pro-active addition to traditional antifouling methods. Using the latest in digital electronics and transducer technology, Sonihull has made a quantum leap forward over the competitors to fill the needs of the marine industry.

Tests have demonstrated that electronic antifouling products have no adverse effect to fish and marine mmamals. The ultrasonic frequencies stay very close to the hull structure and it is demonstrable that the signal does not stray into open water.


Sonihull will save you money!

Before Sonihull

Before Sonihull

Two seasons of growth with antifouling paint.

After Sonihull

After Sonihull

Boat hull after being cleaned and in the water for a season with the Sonihull system.





Sonihull overview
LED Color Normal Status Fault Status Comments
Power On Red ON Flashing Flashing is normal due to incorrectly seated transducers.
Output 1 Green ON OFF OFF when not connected or in fault.
Output 2 Green ON OFF OFF when not connected or in fault.
Status OK Green ON OFF Fault indication, check power and transducers.


Sonihull’s transducers are fully enclosed in thermoformed plastic eliminating all exposed metals. The less expensive alternative, places an aluminum transducer housing in the bilge. Even if the aluminum is anodized, putting aluminum in the bilge is a bad idea.

Sonihull overview


The Sonihull System is available in a single transducer "Mono", or a two transducer "Duo" configuration. Which Sonihull System, or the number of transducers needed is determined by the waterline length of the boat. This chart shows what combination of Mono and Duo sytems are needed to protect your boat.

Transducers are placed near the vessel centerline and about twelve inches or more away from structures like primary bulkheads. As the beam of a boat approaches 20 feet the transducers will need to be positioned futher outboard while reducing the fore and aft separation. A distance of 25 - 35 feet apart will provide effective and efficient hull protection.

≤ 32' 32' - 55' 49' - 65' 59' - 72'
Mono X
Duo X
Mono + Duo X
Duo + Duo X


  1. For twin hull vessels double the requirements.
  2. For cored hulls the transducer must contact the outer skin of the hull.


There are two Sonihull Systems, the Sonihull Mono and the Sonihull Duo. Not sure which Sonihull system is right for you? Contact us  and one of our friendly Sonihull experts will help you.

Sonihull Mono


For yachts up to 32'

Sonihull Duo


For yachts up to 55'



Eight Transducer System


Sonihull Stern Drive Adaptor


Protect your stern drive or saildrive.

Sonihull Sonishaft


Protection for prop shafts & propellers.

Pipe Protector.


Protect your piping from fouling.

Extenion Cable


16.4 feet (5 meter) cable.


These diagrams below show you the approximate positioning for optimal performance for a Sonihull Mono and Sonihull Duo system.
Contact us if your yacht is larger than 55' or BWL is greater than 16'.

Sonihull Mono transducer positioning on power boat.

Sonihull Mono

For boats up to 32 feet

Sonihull Duo transducer positioning on power boat.

Sonihull Duo

For boats 32 - 55 feet

Sonihull Mono transducer positioning on catamaran.

Sonihull Mono

For catamarans up to 32 feet

Sonihull Duo transducer positioning on catamaran.

Sonihull Duo

For catamarans 32 - 55 feet


Here are common questions we receive about Sonihull.

If you can't find an answer to your question, please feel free to contact us 

FAQ - General Questions

How does it work

The Sonihull protection system utilizes the latest digital electronics and Ultrasonic transducer technology, by producing multiple bursts of ultra sonic energy simultaneously in a m ultiple range of frequencies.

This energy produces a pattern of alternating positive and negative pressure. The alternating pattern creates microscopic bubbles during periods of negative pressure and implodes them during periods of positive pressure in a phenomenon known as "cavitation."

The implosion creates a micro-jet action that not only provides the cleaning effect on the hulls surface below the water line, it also resonates and destroys single cell organisms such as algae. The removal of the initial link in the food chain inhibits the growth barnacles and other marine life that feed on the algae.

Does it really work?

Although the concept of using ultrasonic for keeping your boat hull clean is a relatively new application, the concept of ultrasonic cleaning is not new, it has been around for over 30 years, used for a wide variety of applications, from cleaning of dental and medical equipment, fine jewelry, through to de-gunging drains and automotive parts to name but a few, also, in a subject closer to sailors hearts Ultrasonic's is also used for keeping pipes clean in many breweries and hostelries around the world.

Over the past decade, environmental issues have meant much tighter controls on industrial cleaning products especially chlorofluorocarbons, with "necessity being the mother of all inventions" industry needed to find an alternative solution, Ultrasonic cleaning was considered the most viable solution, by embracing the latest in digital electronics and transducer technology, the industry made a quantum leap forward over the last decade to fill the needs of industry.

What is Cavitation

"Cavitation" is the rapid formation and collapse of millions of tiny bubbles (or cavities) in a liquid. Cavitation is produced by the alternating high and low pressure waves generated by high frequency (ultrasonic) sound. During the low pressure phase, these bubbles grow from a microscopic size until, during the high pressure phase, they are compressed and implode.

Is Sonihull system harmful to fish or marine mammals?

Tests show that there is no danger to fish or marine mammals, (but if they can hear the ultra high frequencies and don't like it, they only have to swim a few more inches away from the hull to avoid the problem!)

Will I still need to paint my boat with antifouling paint?

Painting the hull is not only for purpose of antifouling. it is also an important waterproofing barrier, protecting the gel coat from the effects (and immense cost) of osmosis. Therefore we would still recommend that the boat is protected under the water line. In some cases to maximize performance some yacht owners who have installed the sonihull system have opted to use a harder grade of antifouling paint, as apposed to the soft self polishing versions which have a higher drag factor through the water. So although there is still a need for painting below the water line, when using the sonihull system the need to do so will be greatly reduced.

Will Sonihull work on a yacht over 60' in length?

Yes, the same laws of physics apply but due to the surface area of the hull below the water line, several sonihull's would need to be installed to get the desired effect. Please also note that the transducers need to be bonded to the inside of the outer skin of the hull so please check that you can access this as some yachts have inner skins with a filled cavity that would hinder the acoustic transfer of the sound waves.

Which glue should I use to bond the transducer to the hull?

We recommend an epoxy glue such as araldite or equivalent. You will note that there is a gutter built in to the locking ring that is bonded to the hull, this is to prevent any access glue getting into the thread. It is also recommended to apply a little pit of petroleum jelly to the thread to protect it from any epoxy that gets squidged in to the thread.

Will Sonihull work on wooden boats?

No, sorry, but due to the low density of wood and the quantity of joints makes for poor acoustic transmission of high frequencies, so making the unit far less effective for this application.

What is the best type of hull for Sonihull?

A Sonihull is suitable for all single skin GPR, aluminium and Concrete hulls. Foam Core hulls have special installation requirements.

Why Choose Us?

> TomBuoys Ltd is an online supplier of innovative marine brands that offer a better boating experience for both the leisure and commercial customer. . If you do not see exactly what you need, please get in contact as we will source it for you if possible.

We welcome enquires from the marine industry, clubs and organisations as well as private individuals. We cater from a single fender or buoy to any size project based in the UK or worldwide.

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