Thickness Measurement and Hull Inspection in Saint-Nazaire

Inspection services for ships at Saint-Nazaire

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

Gauging locations along the Loire estuary

The LNG terminal at Montoir-de-Bretagne and the refinery jetties at Donges are the two energy berths. LNG carrier thickness measurement here is limited to what the terminal's gas-safety rules and the ship's permit-to-work allow during cargo operations, which usually means ballast tanks, empty on a laden arrival, and the weather deck where the terminal permits electronic instruments. Thickness gauging at Donges follows the same logic on crude and product tankers: ballast tanks and deck structure at the jetty, with cargo-tank work kept for a gas-free yard stay after the ship leaves the estuary.

The Montoir cargo terminals and the Saint-Nazaire basins, entered through locks, give longer and simpler windows for dry-cargo ships. Container ships, ro-ro ships and bulk carriers can be gauged in holds, ballast tanks and on deck during their stay, and ships laid by in the basins suit pre-purchase or condition surveys. For an owner's newbuilding team at the shipyard, any independent UT of welds or thickness checks on owner-furnished items is arranged through the owner and the yard, and the yard's quality control and the class newbuilding survey remain the acceptance route.

• Montoir LNG terminal — ballast-tank and deck gauging on LNG carriers within the terminal's gas-safety rules, usually on a laden arrival with ballast tanks empty.
• Donges refinery jetties — ballast-tank and deck structure gauging on crude and product tankers, with cargo tanks left for a gas-free yard stay.
• Montoir container, ro-ro and dry-bulk terminals — hold, hatch coaming, ballast-tank and deck gauging on cargo ships during their call.
• Saint-Nazaire wet basins behind the locks — ships laid by between employment, suited to pre-purchase, on-hire or condition gauging worked over consecutive days.
• Estuary anchorage off Saint-Nazaire — launch-served ballast-tank gauging on deep-draught ships waiting for a berth or for the tide.
• Nantes upriver berths — gauging on smaller cargo and river-sea ships, reached by road on the same mobilisation.
• The cruise newbuilding yard, for owners' site teams — independent weld UT or thickness spot checks on owner-furnished items, arranged through the owner and the yard.

Regulation and market context on the Loire

Saint-Nazaire is outside every SOx ECA in force today: the Bay of Biscay lies well south of the North Sea ECA's 48°30'N limit. IMO's decision at MEPC 84 in 2026 to create a North-East Atlantic ECA ends that: the amendment enters into force on 1 September 2027, and the 0.10% sulphur limit reaches the French Atlantic coast in September 2028. Product tankers and short-sea ro-ro ships trading regularly into the Loire will then burn ECA fuel or run scrubbers in ECA mode all the way in, and owners planning dockings over the next two years can add scrubber piping gauging to the scope now.

Ships calling on the Loire are inspected under the Paris MoU regime, and each call counts towards the owner's EU ETS and FuelEU Maritime obligations, in force since 2024 and 2025 respectively. For in-service tankers at Donges the ESP framework applies, with IACS UR Z10.4 for double-hull oil tankers, and charterers and oil-major vetting often ask for CAP on tankers over about 15 years; a product tanker on regular Donges service is a typical case for planning that gauging into its next docking. LNG carriers calling at Montoir are not ESP ships and are gauged under UR Z7 and their society's gas carrier rules, with the inner hull of membrane ships measured from the ballast side.

Wherever a ship is outside a sulphur emission control area, the global 0.50% sulphur cap applies, and many of the ships calling at Saint-Nazaire 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 Saint-Nazaire

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

Nantes Atlantique Airport is the closest international airport, and Paris Charles de Gaulle with a high-speed train towards Nantes and Saint-Nazaire is the alternative when connections from India suit it better. The ship's agent arranges ISPS passes for the LNG and oil terminals, which have their own induction and safety requirements, and launch boats for ships at the estuary anchorage. Each technician needs a Schengen visa, applied for in India once the call or docking date is firm, with an invitation letter from the owner or agent. Tidal windows can shift berthing times, so boarding is confirmed with the agent on the day.

• 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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