Authorized Sonihull distributor in Taiwan
Originally developed by NRG Marine (UK); part of Sweden's Alfa Laval since 2025
Technology
The control unit emits ultrasonic pulses in a multi-frequency sweep (19.5–55 kHz for Duo, Quad, 06 and 08; 18–48 kHz for Xtreme), transmitted through steel, aluminium or FRP structures to the surfaces in contact with seawater.
Microscopic bubbles repeatedly form and collapse on the wetted surface — non-inertial cavitation. According to the manufacturer, the energy is too low to erode metal or coatings, yet it inhibits biofilm formation so that barnacle and mussel larvae find it harder to settle.
Different structures respond differently to ultrasound; the system offers multiple frequencies and output modes to match the material, plate thickness and shape at each mounting location and the equipment being protected.
About
The Sonihull ultrasonic anti-fouling system was originally developed by NRG Marine in the UK and has been part of Alfa Laval since 2025. According to the manufacturer, it is installed on thousands of vessels worldwide.
According to the manufacturer, transducers are fixed to the dry side of the hull, sea chests, coolers or pipework, away from seawater, and a control unit drives multi-frequency ultrasound that inhibits biofilm formation on wetted surfaces and makes it harder for barnacle and mussel larvae to attach. No biocides or chemicals are used; the transducers need no through-hull penetrations, and dry-docking is usually not required.
According to the manufacturer, keeping the hull and propeller smooth helps maintain energy efficiency, and keeping sea chests and cooling systems clear reduces the risk of overheating and unplanned downtime; actual results depend on vessel condition and operation.
Hallmark Marine is Sonihull's authorized distributor in Taiwan and has completed installations on high-speed passenger ferries on the Kinmen–Xiamen route. It provides application review, installation guidance and sea trials, scheduled maintenance and repair, and genuine spare parts supply; multi-vessel operators can also ask about the manufacturer's fleet agreements.
How it works
According to the manufacturer, ultrasonic transducers are bonded with epoxy to the dry side of the hull, sea chests, coolers or pipework. A control unit sends multi-frequency ultrasonic pulses through the steel plate (or aluminium or FRP) to the side in contact with seawater. At the wetted surface this produces "non-inertial cavitation", in which microscopic bubbles repeatedly form and collapse. The energy is very low and according to the manufacturer, does not erode metal or coatings, yet it inhibits biofilm formation and makes it harder for barnacle and mussel larvae to attach. The system is preventive: it cannot remove established hard fouling, so surfaces must be cleaned before installation.
Video
System design
Acoustically, different parts of a vessel behave differently: shell plating thickness varies, and frames and stiffeners affect how ultrasound travels through the steel; the areas around the propeller, shaft and side thrusters, as well as sea chests, box coolers, heat exchangers and pipework, also differ in material, shape and flow conditions. According to the manufacturer, effectiveness depends on how ultrasonic energy is distributed and controlled — more transducers or higher output is not necessarily better. Sonihull transducers are therefore arranged according to the structure and the areas to be protected, with operating programmes set individually or in groups.
The Xtreme supports up to 16 transducers, which can be set individually or in groups to run different operating programmes for each protected area.
According to the manufacturer, transducers are arranged at multiple points at low energy so that the required energy reaches the right surfaces; more power does not mean better anti-fouling performance.
Effectiveness depends on transducer position, the material and thickness of the mounting surface, and the medium on the other side; the manufacturer plans positions and frequencies from the vessel's drawings, while Hallmark Marine handles on-site assessment and installation guidance.
Benefits
According to the manufacturer: up to 3% fuel savings over 5 years compared with an uncleaned propeller
Full-year 2025 data from three Australian sister ships (1 fitted, 2 as controls): in the 12–14 kn speed range, the fitted ship's fuel efficiency was about 12%/16% higher than the two sister ships respectively, and about 4%/5% higher across all speeds; about 403 tonnes less fuel used over the year, with payback in about 6.6 months
According to the manufacturer: up to 30% lower cooler maintenance costs and up to 50% less cleaning downtime, depending on the application
According to the manufacturer: mechanical cleaning intervals are typically extended from months to years
Benefit figures are manufacturer case studies or claims; actual results depend on vessel type, condition and operating profile.
References
Catalogue
Overview of the Sonihull ultrasonic anti-fouling system, 5 pages, approx. 0.8 MB.
Download catalogue PDF →Application brochure for small and mid-sized vessels, 5 pages, approx. 0.7 MB.
Download catalogue PDF →