Ultrasonic Thickness Measurement for Ships on the Foyle at Londonderry

Inspection services for ships at Londonderry

Each service has its own page with the method, the class requirements and what the report contains.

Where a ship can be gauged on the Foyle

Most gauging on the Foyle happens at the Lisahally terminal while cargo is being worked. The quay is a working bulk berth, so the team coordinates with the stevedores: hold readings are taken behind the grabs once a hold is empty and swept, tank entry follows the ship's enclosed-space permit, and deck work keeps out of the crane's swing. Fuel tankers discharge under tighter rules, with loose equipment and anything that could cause a spark kept away from the manifold, so tanker work alongside concentrates on deck plating, cargo and ballast line runs, vent heads and air pipes that the master releases to the team.

The city-centre berths and the pontoons of the Foyle Port Marina take smaller ships, including cruise ships of modest size, where short in-service checks are realistic within a day's call. A ship waiting in the lough for the tide or for a free berth can be boarded by launch through the agent, but anchorage stays here tend to be short, so the scope has to be small. Anything that needs dry access to the bottom shell, sea chests or rudder means a docking elsewhere; in that case we measure the internal structure on the Foyle call, so that the external work in dock begins from known figures.

• Lisahally bulk berths — hold, hopper and topside tank gauging on feed, fertiliser and coal carriers during discharges that run over several days.
• Lisahally liquid-bulk discharge — deck, cargo-line and ballast-line UT on product tankers within the terminal's permit rules.
• Lisahally cruise calls — engine-room, grey-water and scrubber piping on cruise ships alongside for the day.
• City-centre quays and Foyle Port Marina — short in-service checks on smaller cruise and passenger vessels lying near the city.
• Lough Foyle anchorage — limited launch-borne deck and air-pipe readings on ships waiting for the tide or a berth.
• Docking elsewhere — internal structure gauged at Lisahally ahead of a drydock at Belfast or at a yard in Britain.

Port state control and paperwork for ships calling at Londonderry

Londonderry is a UK port, so port state control is the job of the Maritime and Coastguard Agency, which continues to apply the Paris MoU regime through UK law. Bulk carriers and tankers calling at Lisahally are selected on the same risk-based targeting used across the region, and older ships on the bulk trades draw attention to hold frames, hatch covers and coamings, ballast tank coatings and the other structural items that most often lead to detentions. A recent set of thickness readings kept on board lets a master answer an inspector's questions about wastage that is plainly visible on deck or in a hold.

Lough Foyle has an unusual status: the UK and Ireland have never settled where the boundary runs through its waters, and the channel to Lisahally passes close to the Donegal shore on the way in. For the ship, the working regime is the UK one, with Foyle Port running the channel and berths and the MCA carrying out inspections. Britain carried the EU ship recycling rules into its own legislation when it left the EU, and many vessels on these routes also call at Irish or continental ports where the EU regulation requires an Inventory of Hazardous Materials, so the inventory is a document most ships here already hold. Cruise ships meet the widest range of checks, because one itinerary around the island can alternate between UK and EU ports.

Wherever a ship is outside a sulphur emission control area, the global 0.50% sulphur cap applies, and many of the ships calling at Londonderry meet it with an exhaust gas cleaning system rather than compliant fuel. Scrubber wash-water piping, the overboard discharge and the hull penetration around it corrode quickly in service, especially on open-loop systems, and are worth adding to the gauging scope.

How a thickness measurement job runs at Londonderry

The sequence for a thickness measurement job at Londonderry is short and written down, so the yard, the surveyor and the superintendent know who arranges what.

City of Derry Airport at Eglinton is the nearest airport but has few routes, so long-haul arrivals usually come into Belfast International or Dublin and continue by road. Arriving through Dublin means clearing Irish immigration first; the land border into Northern Ireland has no routine checks, yet the team still needs valid UK permission for a job at Lisahally, so we choose the route to match the visas held. UK visas are applied for as soon as the call is fixed, and gate access to the terminal and any launch for the lough are arranged through the ship's agent.

• Send the vessel name or IMO number, ship type, class society, the survey due (annual, intermediate, renewal survey number, CAP or owner's condition survey), the port and dates, and the scope you expect.
• We confirm the scope against the class rules for that survey, prepare the thickness measurement plan with frame and section references, and say whether the measurement will be credited to a class survey.
• Mobilisation is planned around visa lead times and the vessel's schedule; the ship's agent arranges port access, and the yard or ship arranges staging, lighting, ventilation and gas-free certificates.
• Gauging with calibrated ultrasonic thickness gauges: through sound coatings only where the gauge's through-coating mode has been verified on a coated reference, otherwise on cleaned bare steel, with every reading tied to its frame, strake and location on the sketch.
• Readings are compared with original thicknesses as work proceeds; substantial and excessive corrosion and any cracks are reported to the attending surveyor and the superintendent the same day.
• The final report is issued on the class thickness-measurement formats with sketches, a summary of locations exceeding the allowable margins, piping tables where piping was in scope, and the gauge calibration and technician certificates.

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