A Royal Navy drone boat has collided with a sailing yacht in one of Britain's busiest waterways, and the Navy is now investigating how its uncrewed vessel came to hit a boat that, by several accounts, had right of way.
It happened earlier this month somewhere inside Portsmouth Harbour. The uncrewed craft was a Rattler, one of the Royal Navy's experimental surface drones. The yacht was Lutine, a 55-foot X-55 racing yacht owned by the Lloyd's Yacht Club. She took a gouge to her starboard stern and went into dry dock at Hamble Point for repairs. Both craft came away with minor damage, and nobody was hurt.
A short statement and a lot of open questions
The Royal Navy has said little. Its spokesperson confirmed "an incident which occurred between a Royal Navy Rattler craft and a civilian yacht during a controlled training exercise in an area within Portsmouth Harbour," and left it there. Guy Williams, commodore of the Lloyd's Yacht Club, was briefer still: "We can confirm the incident occurred but have nothing else to add."
What the Navy hasn't said is the part that matters for anyone who shares that water. It hasn't confirmed whether the Rattler was running autonomously or under direct remote control when it hit. It hasn't said whether the safety boat meant to shadow these drones tried to intervene. And it hasn't touched the awkward part: by several accounts the yacht was under sail and had right of way when the drone struck her.
The Rattler programme
The Rattlers are rigid-inflatable boats converted into uncrewed surface vessels, built by SYOS Aerospace in Fareham. Seven of them, Rattler 1 through 7, have been trialling in and around Portsmouth Harbour since March 2026 under the Royal Navy's Fleet Experimentation Squadron.
They aren't left to their own devices. Under the King's Harbour Master's notices to mariners, a human operator drives each drone from a Remote Operating Centre, and a dedicated safety vessel — a patrol boat or workboat — is supposed to ride alongside, its crew ready to step in if something goes wrong. The trials are meant to comply with COLREGs, the international collision-avoidance rules, and to hold at least 200 metres clear of other traffic, aborting the run if a close-quarters situation develops.
The safety net that didn't catch it
On paper it's a well-layered system: a human at the controls, a safety boat alongside, a 200-metre bubble, COLREGs on top. The collision happened anyway. That's what makes it more than a fender-bender.
Portsmouth Harbour is a working commercial waterway, shared daily by ferries, commercial traffic and leisure sailors — not some remote testing range. Marine Industry News reported that a Gosport ferry and a tug had already had to take evasive action during earlier Rattler trials. Putting autonomy-capable craft into that kind of traffic, instead of an empty range, is what the whole safety argument turns on — and a give-way yacht getting hit is exactly the outcome the layered system was built to prevent.
There's a neat irony in the victim, too. Lutine belongs to the Lloyd's Yacht Club, tied to Lloyd's of London — the insurance market whose "Lutine Bell" was historically rung for ships lost at sea. A marine-insurance institution's yacht getting hit by a naval drone isn't the advert the autonomy programme wanted.
What reports add, with a health warning
Some of the more colourful details come from a single tabloid source and remain unconfirmed by the Navy or the yacht club: reports have put the yacht's value at around £400,000 and quoted an anonymous harbour source describing the drone as having "gone rogue" before the collision. The load-bearing points hold up regardless: an uncrewed Navy vessel hit a civilian yacht, the yacht was damaged, nobody was hurt, and the Navy is investigating.
Why it matters
This looks like the first collision between a Royal Navy uncrewed surface vessel and a civilian boat in a UK harbour. And it lands right where the industry has been nervous for years: what happens when an autonomy-capable craft, however well supervised, meets ordinary traffic in a crowded harbour and the safeguards don't hold. The Navy's inquiry may settle the narrow questions — autonomous or remote, whether the safety boat reacted, who gives way to whom under COLREGs when one boat has no crew aboard. The bigger one is harder to close, and Portsmouth Harbour has just handed everyone a concrete reason to ask it.
Photo: Royal Navy / Crown Copyright, via DroneLife. Source: Marine Industry News.
