Thickness Gauging for Ships in the Cádiz Bay Drydocks

Inspection services for ships at Cádiz

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

Drydock gauging around the Bay of Cádiz

Most gauging in the bay is done inside Navantia's Cádiz ship-repair yard, either at the repair quays before and after docking or in the dock itself. In the dock, the bottom and side shell can be measured from outside, the yard's gas-free certification and ventilation regime governs tank entry, and staging or lifts give access to high structure in holds and tanks. The yard's planning sets when each space is open, so the gauging programme is tied to the yard schedule and updated daily with the ship's superintendent.

Two rounds of measurement are common. The first, before or at the start of the docking, gives the surveyor and the yard the corrosion picture and the steel list; the second, after cleaning, blasting or cropping, confirms the thickness of areas left in place and the extent of renewal. For cruise ships, the volume of tanks and voids means the technicians often work in parallel with tank cleaners and painters, which needs close coordination with the yard's permit system. Ships waiting for a dock slot at anchor in the bay can be gauged by launch beforehand, which shortens the time the ship spends in the dock itself.

• Navantia's Cádiz ship-repair yard — in-dock gauging of bottom shell, tanks, holds and decks for renewal and docking surveys on large merchant ships
• Repair quays at the yard — pre-docking and post-undocking gauging alongside, including ballast tanks, piping and deck structure
• Cádiz Bay anchorage — pre-docking gauging by launch on ships waiting for a dock slot, so the steel list is started early
• Cruise berths in the port of Cádiz — short sea-water line and cofferdam checks on cruise ships making day calls, planned with the technical department
• Port terminals at Cádiz and the Zona Franca — gauging on bulk carriers, ro-ro and container ships calling for cargo
• Gibraltar and Algeciras — nearby ports where gauging can begin on passage before a ship continues to a docking in the bay

Regulation and market context for Cádiz dockings

Cádiz lies on the Atlantic side of the Mediterranean SOx ECA boundary, so ships docking here are outside the ECA but enter it within hours of sailing east. That makes a Cádiz docking a natural moment to inspect scrubber systems before a Mediterranean season: wash-water and overboard lines, their discharge valves and the adjoining shell plating can be gauged and renewed in the dock, where access from outside is easy. Port state control in the port follows the Paris MoU, applied by the Spanish maritime administration through its local harbour master.

Cruise ships and gas carriers are among the ship types most associated with the yard, and both have particular gauging needs. Cruise ships run large ballast, fresh water, grey and black water tank systems that are only fully accessible in dock, and their docking periods are short and tightly scheduled. Gas carriers' hull and ballast tank structure is surveyed under the class rules for their type, while their cargo containment is a separate specialist matter outside ultrasonic gauging. Since EU ETS reached shipping in 2024 and FuelEU Maritime followed in 2025, more dockings also include energy-saving retrofits, which open structure that needs measuring before it is modified.

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

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

Technicians fly from India to Jerez or Seville, usually via Madrid or another European hub, and reach Cádiz by road; Málaga and Gibraltar are alternatives. Yard access is arranged through the shipyard and the ship's superintendent, with induction and safety passes issued at the gate, while anchorage work is arranged by the ship's agent with a launch. Schengen visas are needed, and since dockings in the bay are typically booked months ahead, we align visa applications with the docking date and the yard's planning meetings.

• 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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