Ship Thickness Measurement in Gibraltar's Anchorages and Drydocks

Inspection services for ships at Gibraltar

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

Gibdock, the anchorages and the berths: where Gibraltar gauging is done

Drydock work at Gibdock is the most complete setting for thickness gauging in Gibraltar: tanks are gas-freed and ventilated under the yard's safety system, staging or access equipment is arranged through the yard, and the bottom shell can be measured from outside once the ship is on blocks. Gibdock thickness measurement is usually split into two phases — a pre-docking or first-day survey to firm up the steel renewal list, and measurements after cleaning or blasting where the surveyor wants confirmation of what remains.

Anchorage work is done by launch, booked through the ship's agent under the Gibraltar Port Authority's rules for service craft. The Eastern Anchorage on the Mediterranean side is exposed to the Levante, and in strong easterlies launch transfers there can be suspended, so anchorage jobs carry weather float in the plan; the Western Anchorage inside the bay is more sheltered from that wind. Alongside berths are few, so most commercial ships are gauged either at anchor or in the dockyard. Gibraltar's compactness helps: a team on a docking job at Gibdock can take an anchorage job between yard shifts without a second mobilisation.

• Gibdock drydocks — renewal and docking survey gauging, external bottom shell readings and post-blast confirmation measurements during repair periods
• Western Anchorage in the Bay of Gibraltar — bunkering, stores and crew-change calls used for targeted gauging and pre-purchase sampling
• Eastern Anchorage on the Mediterranean side — anchorage gauging and on-hire or off-hire condition readings, with weather float for Levante conditions
• Cruise terminal berths — limited alongside work such as piping and void gauging during turnaround or repair calls
• Algeciras and the Bay of Cádiz — nearby Spanish ports where the same technicians can continue if the ship's next call is across the bay or along the coast

Flag, port state and fuel rules on the Rock

Gibraltar's maritime affairs are handled by the Gibraltar Maritime Administration, which runs the Gibraltar Ship Registry, and by the Gibraltar Port Authority, which controls the harbour and the anchorages. Port state control and flag inspections are matters for the Gibraltar authorities rather than for Spain, and owners of Gibraltar-flagged ships deal with a register that sits alongside the UK and the other Red Ensign registers. Because Gibraltar is outside the European Union, owners whose ships trade between the Rock and EU ports should check with their compliance teams how those calls are treated for EU ETS and FuelEU Maritime.

On sulphur, Gibraltar lies within the Mediterranean SOx ECA, so the ECA limit has applied to ships here since 1 May 2025. Ships arriving from the Atlantic change over fuel or bring their scrubbers into ECA mode as they approach, and scrubber-equipped ships taking bunkers at anchor are a regular source of piping inspection work: wash-water lines, overboard discharges and the shell areas around them corrode quickly once a system has run for several years. Because Gibraltar's bunkering trade means many ships plan short stops here deliberately, it is a convenient place to slot in targeted gauging before a docking elsewhere, or to confirm a defect the crew has reported on passage.

Since 1 May 2025 the whole Mediterranean has been a sulphur emission control area, so ships calling at Gibraltar burn 0.10% sulphur fuel or run a scrubber. Scrubber wash-water piping, the overboard discharge and the hull penetration around it corrode quickly in service and are worth adding to the gauging scope at every docking.

How a thickness measurement job runs at Gibraltar

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

Technicians fly to Gibraltar International Airport via a UK connection, or to Málaga and cross the land frontier at La Línea by road. Entry rules for Gibraltar and for transit through Spain both have to be checked, and the routing chosen decides which visas the team needs, so we confirm the current requirements with the ship's agent before flights are booked. Dockyard access is arranged with Gibdock through the agent; for anchorage jobs the agent books a launch and confirms it against the ship's bunkering or service schedule. Early notice of a docking date lets the visa steps finish without squeezing the job.

• 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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