UK Funds $54.8M Sonobuoy Upgrade to Strengthen Merlin Mk2 ASW Against Russian Submarines.

On February 2, 2026, the Royal Navy confirmed a $54.8 million contract with Ultra Maritime to supply sonobuoys for its Merlin Mk2 helicopter fleet. The purchase strengthens Britain’s ability to detect and deter hostile submarines near critical undersea infrastructure and nuclear deterrent patrol routes, a priority that also carries implications for NATO and US maritime security. On 2 February 2026, the Royal Navy announced that the UK Ministry of Defence has signed a $54.8 million contract with Ultra Maritime to supply sonobuoys for the Merlin Mk2 helicopter force, a purchase designed to reinforce Britain’s anti-submarine shield as foreign undersea activity intensifies around the British Isles. The deal is being positioned not as routine sustainment but as a deterrence-driven upgrade, tied directly to protecting the nuclear deterrent and safeguarding critical undersea infrastructure. The dollar figure reflects a conversion from the £40 million contract value, using an exchange rate of roughly $1.37 per pound on the day of the announcement.
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Ultra Maritime's new $54,8 million sonobuoy contract will equip Royal Navy Merlin Mk2 helicopters with fresh passive and active acoustic sensors, strengthening the UK's ability to detect, track, and deter Russian submarines operating near British waters and critical undersea infrastructure (Picture source: UK Navy).

Sonobuoys are not “just consumables” in modern ASW, they are the fastest way to seed an acoustic picture in the exact patch of water a commander cares about, at the time they care about it. Dropped from a hovering helicopter or a low-altitude transit, a buoy splashes down, deploys a float and antenna, then lowers a hydrophone to a selected depth to listen, or to transmit acoustic energy depending on type. In Royal Navy service, the Merlin’s tactical edge comes from blending buoy fields with its dipping sonar, allowing crews to probe specific layers and thermoclines, rapidly classify contacts, and keep pressure on a submarine that is trying to exploit complex littoral acoustics.

The technical story inside this contract is the mix of buoy roles and the data they push back to the aircraft. Ultra Maritime’s SSQ-955 HIDAR passive directional buoy, for example, is a compact “G-size” design of roughly 5.6 kg that digitises acoustic data and can transmit it in a high-rate mode at 224 kbps with 14-bit precision, a useful trait when the ocean is loud and operators need dynamic range rather than a smeared signal. It offers multiple programmable depth settings and endurance selections up to six hours, with telemetry across VHF channels 1 to 99. For broad-area passive surveillance, the SSQ-906 LOFAR variant pairs the same digital electronics with an omni-directional sensor and a wide acoustic band quoted at roughly 10 Hz to 20 kHz, with operating life selectable up to seven hours and shallow-water variants designed to cope with low salinity near estuaries.

The Merlin Helicopter Force has fielded multistatic active processing and increased the number of concurrently processed buoys to more than 30, a jump that materially changes how quickly a contact can be boxed and trailed compared to older, few-channel workflows. In that construct, an active source buoy such as Ultra’s SSQ-926 ALFEA acts as a coherent low-frequency projector in the 1.6 to 2 kHz band, controlled by UHF commands and paired with passive receivers like HIDAR across a buoy field. The result is a distributed sonar geometry that can exploit bistatic and multistatic returns, complicating a submarine commander’s counter-detection problem and improving localisation when a single monostatic ping would be ambiguous. Ultra also fields the SSQ-963D CAMBS as a directional, monostatic active localisation buoy with selectable power profiles, including an hour at full power or several hours at reduced power, giving planners flexibility for rapid prosecution or persistent barrier tactics.

The Royal Navy announcement is notable because it treats the buy as both capability and industrial policy. The contract scope explicitly includes design, development, engineering, and manufacturing, and the company’s UK footprint is being expanded through an integrated design and production facility at Greenford in west London, described as a £20 million investment with additional capacity for scaling output. That matters because buoy inventories are consumed at the speed of operations and training, and surge resilience becomes a strategic variable if the North Atlantic picture deteriorates. Parallel to the manned-helicopter line, Ultra is also working with the Ministry of Defence on miniaturised sonobuoys for uncrewed air systems, and reporting indicates a UK-funded push toward next-generation G-size multistatic transmit and receive buoys aligned with future rotary-wing uncrewed concepts and potential integration with platforms such as MQ-9B SeaGuardian. In procurement terms, this reflects a joint development model in which frontline operators define tactical requirements, government science and technology bodies accelerate prototypes, and industry industrialises what survives trials.

The Royal Navy has repeatedly tracked Russian submarines operating in the North Sea and North Atlantic approaches, including modern nuclear-powered attack submarines armed with long-range cruise missiles. The undersea contest is also increasingly tied to grey-zone pressure on seabed infrastructure, from data cables to energy links, where intelligence-gathering vessels and submarines can map or surveil critical networks without crossing the threshold of open conflict. Against that backdrop, Merlin’s ability to rapidly deploy a buoy pattern, dip its sonar, classify contacts, and if required prosecute with a lightweight torpedo is not a niche skill but a daily insurance policy for carrier strike escorts, deterrent transit corridors, and NATO’s wider undersea awareness picture.

The $54.8 million award fits a sustained procurement cadence rather than a one-off purchase. Over the past decade, the Ministry of Defence has relied on a series of follow-on contracts to keep the Merlin sonobuoy inventory current, covering engineering updates, manufacturing, logistics, and support across both passive and active types. In plain terms, the UK is paying to keep an acoustic magazine full, because without buoy stock the best-trained crews and the most advanced mission systems still fly blind. The strategic signal is clear: London expects the undersea contest around UK waters to remain crowded, contested, and unforgiving, and it is investing in the sensors that give Merlin crews the decisive advantage of first detection, confident classification, and a firing-quality track if deterrence fails.