Ultrasonic Thickness Measurement in Istanbul: Tuzla Shipyards and Bosphorus Anchorages

Inspection services for ships at Istanbul

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

Where gauging happens in and around Istanbul

Most structural gauging is done in the Tuzla shipyard zone, with ships in floating docks or alongside repair quays. The usual pattern is pre-docking gauging, at anchor off Tuzla or at the last cargo port, followed by in-dock gauging of bottom, side shell and tanks once the ship is dry and spaces are cleaned. Late readings hold up a yard's steel programme, so we plan the sequence with the superintendent and the yard's project manager so that measurement stays ahead of the steelwork and renewal decisions can be made area by area. Thickness measurement in Turkey's yards is as much about timing as about the readings themselves.

Outside the yards, gauging is done at the Ambarlı container and general cargo terminals during port stays, and at the anchorages off the city. Ships waiting for a Bosphorus transit can be boarded by launch for deck, hatch cover and ballast tank readings, but the plan must allow for the ship being ordered to proceed. We agree a priority list so that the most important spaces are measured first, and anything left over is picked up at the next cargo port or in dock.

• Tuzla shipyard zone — renewal-survey and pre-docking gauging, bottom and side shell in floating docks, tanks and holds alongside the repair quays
• Anchorages off Tuzla — pre-docking gauging on ships waiting for a dock, giving the yard a steel estimate before the ship arrives
• Ahırkapı anchorage at the southern entrance to the Bosphorus — targeted gauging on ships waiting for transit or orders, reached by launch
• Ambarlı terminals on the European side — container ships and general cargo ships gauged during port stays under terminal ISPS rules
• Anchorages at the Black Sea entrance to the Strait — deck, hatch cover and ballast tank readings on ships awaiting southbound transit
• Altınova shipyards in Yalova — follow-on jobs across the mouth of the Gulf of Izmit, reached by road or ferry in the same mobilisation

Port state control, the Turkish Straits and emissions rules

Turkey is a member of both the Black Sea MoU and the Mediterranean MoU on port state control, and ships trading between Black Sea and Marmara ports are inspected regularly. Older bulk carriers and general cargo ships on Black Sea trades attract attention for structural condition, and deficiencies found during port state control, such as wasted hatch coamings, holed ventilators and corroded air pipe heads, are often what prompts an owner to commission gauging ahead of schedule. Turkish-flagged ships and ships managed from Istanbul are classed with a range of societies, including the Turkish society alongside the larger international ones.

On emissions, the Mediterranean SOx ECA that took effect on 1 May 2025 ends at the entrance to the Dardanelles, so the Sea of Marmara, Tuzla and the Black Sea all sit outside it and the global 0.50% sulphur limit applies here. Ships sailing on through the Dardanelles into the Aegean cross into the ECA, so many ships calling at Istanbul switch fuel or start their scrubbers on the way out, and scrubber-fitted ships docking at Tuzla offer a good opportunity to inspect wash-water and overboard piping with the hull dry. Ships trading on to EU ports also carry EU ETS and FuelEU Maritime obligations for those voyages, although Turkey itself is not in the EU.

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

A gauging job at Istanbul runs the same way whatever the ship type. The sequence below is what the superintendent, the attending surveyor and the yard can expect from us.

The team flies into Istanbul, using Sabiha Gökçen Airport on the Anatolian side for Tuzla, which is close to the shipyard zone, or Istanbul Airport for Ambarlı and the European side. Yard entry at Tuzla, terminal passes at Ambarlı under ISPS, and launches for ships at the anchorages are arranged through the ship's agent and the yard, with crew lists and certificates sent ahead. Turkey requires visas for Indian passport holders, so we start applications as soon as the docking date is set and plan around the visa's validity if the yard slot moves.

• 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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