Thickness Measurement for Ships in the Cherbourg Roadstead and Harbour

Inspection services for ships at Cherbourg

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

Where gauging can be done at Cherbourg

At the ferry terminal, thickness work follows the sailing timetable. Vehicle decks are measured when they are clear, ramp and door structure is checked while the ship is alongside, and tanks and machinery spaces are worked within the ship's permit system. Because a ferry is a passenger vessel, the superintendent and the master decide which spaces are available and which stay closed until the passengers have left. A longer layover, for instance when the ship is held by weather or schedule, opens up the larger scopes that a quick turnaround cannot.

On the cargo and project quays the pace is calmer. A multipurpose or heavy-lift ship waiting for its cargo can have its holds, hatch covers, tank top and ballast tanks gauged over a day or more, and service vessels for offshore wind give similar windows between rotations. In the roadstead, a launch booked by the ship's agent takes the team to a ship at anchor. Work there depends on swell and wind, and the priority list puts the most important spaces first, in case a change in weather ends the visit early.

• Passenger terminal berths — vehicle deck, ramp, door and ballast tank gauging on ro-pax ferries during layovers.
• Commercial quays — hold, hatch cover and tank top gauging on cargo ships during loading or while they wait for weather.
• Project cargo and heavy-lift berths — deck, hatch and ballast tank readings on multipurpose ships serving the offshore wind industry.
• Cherbourg roadstead anchorage — launch-served gauging on ships waiting for orders or a berth, when sea state allows.
• Port repair quays — wall-thickness checks on piping and deck structure of small and mid-sized ships during repair afloat.
• Offshore service vessel berths — hull and deck gauging on crew transfer and supply vessels between rotations.

Regulation and the Channel traffic picture

Port state control at Cherbourg belongs to the Paris MoU regime, with inspections carried out by the Centres de sécurité des navires of the French maritime administration. Ferries, cargo ships and tankers calling from British and Irish ports are all subject to risk-based targeting, so a ship with visible wastage on a vehicle deck or a corroded hatch cover is a candidate for detailed inspection. Measured thickness figures let the master show the inspector what the structure actually is, instead of arguing from appearance.

Cherbourg stands in some of the busiest water in Europe, close to the Channel traffic separation schemes, and ships that call here do so in the middle of a route that shapes their survey planning. Ferries operate on rolling refit programmes, and cargo ships are docked wherever a yard slot is available. The EU Ship Recycling Regulation's Inventory of Hazardous Materials applies to ships calling at EU ports, and EU ETS and FuelEU Maritime affect every voyage. For ESP ships such as tankers and bulk carriers the Enhanced Survey Programme sets the extent of gauging, which grows with age.

Ships trading to Cherbourg are inside a sulphur emission control area, where fuel must not exceed 0.10% sulphur unless an exhaust gas cleaning system (scrubber) is fitted. Scrubber wash-water piping, the overboard discharge and the hull penetration around it are among the fastest-corroding parts of a modern ship, so they belong in the gauging scope at every docking and, on open-loop systems, between dockings.

How a thickness measurement job runs at Cherbourg

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

From India the team typically flies to Paris and travels on by train through Normandy to Cherbourg, a long but straightforward journey, with the small airport near the town offering limited connections. The ship's agent arranges port passes for the terminal and quay concerned and books the launch for any work in the roadstead. The naval arsenal is closed to civilians and plays no part. Each technician needs a Schengen visa, applied for as soon as the call is confirmed, with an invitation from the owner or agent naming the ship and the port.

• 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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