Frequently Asked Questions

Sonihull is the world’s leading ultrasonic anti-fouling system. Sonihull’s technology uses the power of ultrasound to create fit-and-forget systems that prevent marine biofouling settling on, or in your vessel.

Anti-fouling, is the name given to the measures taken to stop algae, weeds, barnacles, mussels and other organisms (collectively known as bio-fouling) from growing where they are unwanted.

Bio-fouling grows naturally on any unprotected surface that is in contact with fresh water or seawater, from ship hulls, cooling systems and oil rigs to offshore windfarms and fish farms.

Each year, bio-fouling costs the marine sector about $100 Billion in increased fuel and maintenance costs.

Left unchecked, marine bio-fouling can increase hydrodynamic drag by up to 60% with an associated spike in fuel costs and greenhouse gas emissions. Bio-fouling can also clog raw seawater cooling systems, causing main equipment to overheat and fail.

95% of all other anti-fouling systems rely on toxic biocides to kill organisms, and widespread self-polishing coatings that leave poisonous trails of microplastic pollution in their wake.

In contrast, Sonihull is an effective, Zero-Harm, Environmentally-Safe solution to unwanted bio-fouling.

Rugged ultrasound transducers are bonded to the dry side of the equipment or surface being protected.

Ultrasonic pulses from the transducer produce a pattern of increasing and decreasing pressure on the surface being protected. Through the process of ultrasound-induced non-inertial cavitation, microscopic bubbles are created as the pressure drops and are popped as the pressure increases. The process does not cause any surface damage and the ultrasound frequencies used don’t propagate far from the vessel surface and are inaudible to marine mammals and fish.

As well as actively preventing the creation of a biofilm, the micro-jets created during bubble-collapse have been proven to prevent barnacle and mussel larvae from embedding on the surface.

Having a clean hull and propeller on an Aframax tanker (80,000 - 120,000 DWT) will deliver around $2 million in fuel savings during an average 5-year drydocking schedule.

If you are operating with Impressed Current Anti-fouling systems protecting your box coolers, you could save over 90% of Capital and lifetime MRO costs if you replace them with Sonihull systems.

If your vessel is off-duty, due to reduced demand, it is under attack just sitting at anchor. Anti-fouling coatings don’t work when your vessel is stationary and ICAF systems will only work properly when main systems are running. Fitting a Sonihull system will protect idle systems from bio-fouling and avoid the need to drydock before safely re-commissioning.

There’s no need to drydock and there’s no draining, cutting, drilling or welding either. So, there’s no need for Class re-surveying.

Sonihull systems can also be fitted by small, isolated teams in a matter of hours, even whilst at sea. This means that work can be carried out in accordance with COVID-mandated guidelines.


Sonihull uses non-inertial cavitation induced by ultrasound to keep bio-fouling at bay.

The process is an established technology, usually associated with cleaning solid surfaces.

Sonihull ultrasonic anti-fouling systems disrupt the formation and proliferation of marine colonies and provide an effective means of preventing mussels and barnacle larvae from attaching to hard surfaces in raw seawater.

The process of ‘non-inertial cavitation’ should not be confused with ‘inertial cavitation’. The latter is the process that can damage propellers or the insides of pumps. But the forces involved with non-inertial cavitation are much lower.

So, with Sonihull, there is no chance of surface damage, like erosion or pitting. That kind of physical damage can only be caused by inertial cavitation.

The only material that Sonihull does not protect from bio-fouling is wood.

The system relies on internal resonance to transmit the ultrasonic signals to the surface being protected. Compared to man-made materials, wood is full of varying densities and voids and is not an efficient transmitter of ultrasound.

Sonihull provides effective anti-fouling protection for solid materials, including Steel, Stainless Steel, Aluminium, GRP, FRP, Kevlar, Titanium and rigid plastics.

Note – The protection of certain concrete and ferro-cement structures will depend on their individual composition. Silicone-based coatings are known to dampen up to 40% of ultrasonic signals and will reduce system effectiveness.

Each Sonihull transducer only consumes 3.6 Watts per hour.

This makes the system ideal for on-board, standby or remote powering options, using 110-240 Volts 50/60Hz AC or 12-30 Volts DC supplies.


Sonihull’s ATEX range is the world’s only ultrasonic anti-fouling system that is certified for use in hazardous zones (Zones 0, 1 & 2). This makes it an ideal choice for raw seawater cooling systems in offshore oil and gas applications, including deck-mounted LNG and LPG vaporisers.

Ultrasound is beyond the audible spectrum of marine mammals and fish.

The low-powered ultra-high frequencies used by Sonihull are completely harmless to marine mammals and fish. Also, the ultrasound frequencies emitted by Sonihull’s transducers do not propagate far from the surface being protected.

Ultrasound should not be confused with low-frequency sound waves which are within the audible spectrum and can propagate for many miles underwater. Low frequency and sub sonic pressure waves are caused by things like underwater explosions and can be disruptive to large sea-dwelling mammals like whales and dolphins.

Unlike anti-fouling coatings and impressed-current systems, Sonihull does not rely on poisonous biocides, metallic ions or the release of microplastics from ablative coatings to be effective.

The systems are usually fitted on the dry-side of the surface being protected, but they are manufactured to withstand the harsh marine environment.

The control box is IP53 rated and the transducers are IP68 rated. If required, the transducers can even be fitted underwater. In fact, Sonihull has systems that are used on the outside of an underwater hotel, keeping the windows clean.


If there is already an established layer of bio-fouling on your surface it will need to be cleaned off prior to fitting Sonihull. Sonihull may kill the existing soft fouling and prevent further fouling, but any established calciferous fouling will need to be physically removed.

Wherever you have a solid surface that requires protection from marine biofouling.

Sonihull manufactures a wide range of surface adaptors so that its ultrasonic antifouling transducers can be mounted in all kinds of locations to prevent biofouling. Sonihull protects box coolers, sea chests, pipework, intakes, valves, hulls, structures, propellers, shafts, steering gear, stern drives, waterjets...

Sonihull bonds directly to the dry side of the item being protected, there is no drilling, welding, extra classification surveys or drydocking required. Transducers can also be mounted up to 80m from the control unit without any loss in performance, ideal for pre-fabricated structures.

Protect your vessel

Sonihull’s mission is to deliver environmentally safe, cost effective anti-fouling wherever unwanted bio-fouling persists. Our vision is:

To make dosing the oceans with poisonous biocides and microplastics a thing of the past
To deliver effective anti-fouling systems using the power of ultrasound
To save the oceans, one ship at a time