Ultrasonic Thickness Gauging for Ferries and Cruise Ships at Dover

Inspection services for ships at Dover

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

Where gauging can be done at Dover

Dover has no dry dock for ships of ferry or cruise size, so the work here is afloat. Ferries are gauged at their linkspan berths during stand-downs, or at a lay-by berth when the operator rests a ship, and the team works through vehicle decks, ramps, bow and stern doors, tanks and machinery spaces in an order agreed with the chief engineer and chief officer. Vehicle decks come first on most ferries, because lorry wheels, water, road salt and diesel spills wear the plating and the stiffeners beneath it, and the ramps and doors carry heavy cyclic loads at their hinges and locking devices.

Cruise ships alongside in the Western Docks give a different kind of access. During a turnaround the ship is busy with passengers, stores and baggage, but machinery spaces, sea-water piping, tanks prepared by the crew and open decks can usually be reached, provided the work is coordinated with the ship's technical staff and terminal security. Reefer and cargo ships at the cargo terminal work cargo for a day or so, which suits hatch cover, deck and machinery-space checks. Anchorage work in the Downs is possible by launch in settled weather, but the roadstead is open to easterly winds, and the agent's advice decides the day.

• Eastern Docks ferry berths: vehicle deck, ramp and bow or stern door gauging, with crack detection, during stand-down periods.
• Lay-by berths: longer tank, void space and machinery piping scopes on a ferry rested from service or awaiting refit.
• Western Docks cruise terminals: engine-room piping, prepared tanks and open-deck structure on cruise ships during turnaround days.
• Western Docks cargo terminal: hatch cover, deck and sea-water piping checks on reefer and general cargo ships working cargo.
• The Downs anchorage off Deal: short launch-borne scopes on ships waiting for weather or orders, when conditions allow.

Ferry safety, inspection regimes and cross-Channel climate rules

Ferries on regular cross-Channel service are inspected often, whether by the Maritime and Coastguard Agency acting as flag state for UK-registered ships or under port state control for foreign-flagged ones, which the UK applies in line with the Paris MoU. The capsize of the Herald of Free Enterprise off Zeebrugge in 1987 and the loss of the Estonia in 1994 shaped today's rules on bow doors, watertight integrity and damage stability for ro-pax ships, and inspectors still pay close attention to doors, ramps and their securing arrangements. Thickness and crack-detection records on that structure are part of showing it remains sound.

Cross-Channel voyages also fall inside European climate rules. For ships of 5,000 gross tonnage and above, the EU Emissions Trading System counts half the emissions of each voyage between Dover and a French port, and FuelEU Maritime limits the greenhouse gas intensity of the energy used on the same basis. Operators have answered with hybrid and battery-assisted ferries on the short crossing, but much of the fleet is older, and a ferry that may stay in service for years yet needs her structure tracked carefully between refits.

Ships trading to Dover 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 Dover

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

The team usually flies into London Heathrow or Gatwick and continues to Dover by road or by high-speed train from London St Pancras. Technicians travel from India on UK visas, so we ask for stand-down or refit dates as soon as the operator has them. The port's ferry and cruise areas are tightly controlled for security and border reasons; passes are arranged through the operator or the ship's agent against each technician's passport, and the team is escorted wherever the operator or the port requires it.

• 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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