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
Mono System

For yachts up to 32 feet.

Duo System

For yachts up to 55 feet.


Eight Transducer System

The Problem...

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:

  • Reduced speed due to extra drag.
  • Increased fuel consumption, estimated at as much as 20%.
  • Propeller cavitation (which in turn causes extensive damage to propellers)
  • Expensive annual haul outs and repainting costs.

The Solution...

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.

Why Sonihull?

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.

  • Simple, single function control. On/Off.
  • Remote System monitoring option.
  • Quiet operation with no need for a "Sleep Switch" due to noisy operation.
  • Larger acoustic footprint than any competing unit.
  • No exposed metal in the transducers.
  • Automatic low voltage shutdown at approx. 12 volts.
  • Higher quality components allow Sonihull to run cool and quiet so it does not need temperature monitoring system, cooling fan, or sleep switch.
  • Greater coverage per transducer due to better design and component quality.
  • Competing products need up to four times as many transducers for the same coverage.

How Does It Work?

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 mammals. 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!

  • A clean hull and drivetrain can reduce fuel bills by 20% - 30%.
  • Reduced vibration and improved performance.
  • Reduce maintenance costs and expensive haul outs.
  • Suppress diessel bug and keep stored water fresher.
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 two seasons with the Sonihull system.

Vessels protected with Sonihull

Environmentally friendly antifouling system

Sonihull Overview

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.

Transducer Overview

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

Which Sonihull System Is Right For You?

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.

Sonihull Systems

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

Stern Drive Adaptor

Protect your stern drive or saildrive.

Pipe Protector.

Pipe Adaptor

Protect your piping from fouling.

Extenion Cable

Extension Cable

16.4 feet (5 meter) cable.

Where To Position The Transducers?

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 here please feel free to contact us.

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

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.

"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.

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!)

A clean hull can save you 30% of fuel bill, It is common that fouling on the boat's hull will lead to increased resistance, which basically means you are going to burn more fuel for every knot you make. The outcome is compromised efficiency and a poorer mpg figure than with a clean hull, but by how much?

To answer this question a leading yacht journal undertook some comprehensive seatrials in a 10-year-old Princess 430 insatalled with twin Volvo TAMD63P engines rated to 370hp at 2800rpm, measuring its performance before and after its spring lift.

Princess 430 sea trial.

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.

Although we have received a few reports that this is the added benefit of installing an Ultrasonic system, and could be plausible due to the simple sell structure of Jellyfish, to-date there is no scientific data to prove this theory.

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.

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 bit of petroleum jelly to the thread to protect it from any epoxy that gets squidged in to the thread.

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.

A Sonihull is suitable for all single skin GPR, aluminium and steel hulls. Foam Core hulls have special installation requirements, please contact us for details.

Download our Sonihull catalog, installation instructions, price lists right here.
Can't find what you're looking for? Contact us and we'll help you out!

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