Ultrasonic Thickness Gauging for Coasters, Ferries and Workboats in Harlingen

Inspection services for ships at Harlingen

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

Shiplift, repair platform and cargo quays in Harlingen

Dockings at Harlingen use the shiplift rather than a floating or graving dock. The vessel is raised onto the repair platform or moved into a covered hall, where the bottom, sides, rudder, sea chests and propeller area stay exposed for as long as the work needs. For thickness gauging that is close to ideal: the yard provides staging and lighting, the halls keep surfaces dry for couplant and marking, and the class surveyor can follow the close-up programme at the same time. Plates found with substantial or excessive corrosion can be marked directly on the steel for the yard's renewal crew.

Gauging afloat takes place at the cargo quays, the ferry harbour and the yard's repair berths. Coasters can be measured hold by hold while cargo work continues elsewhere on board, and ballast tanks can be added if the crew can empty and ventilate them within the call. Ferries are best gauged when the operator rotates a vessel out of the timetable. Ships with afloat repairs but no docking due often lie at the yard's berths, and those periods suit piping, deck and tank gauging that defines what has to be replaced. Deep-draught ships cannot reach Harlingen, so the yard's work and the port's traffic both centre on small and mid-sized vessels.

• Damen Shiprepair Harlingen shiplift and repair platform — renewal and docking survey gauging of shell, double bottom, sea chests and holds with the ship dry.
• Covered blasting and repair halls — hull, tank and internal structure readings taken under cover, unaffected by wind or rain.
• The yard's repair berths — afloat gauging of piping, decks and tanks during repair periods that do not need a docking.
• Cargo quays in the commercial harbour — hold, tank-top, hatch cover and coaming readings on coasters between discharge and loading.
• Ferry harbour — deck, ramp, void and shell readings on the Terschelling and Vlieland ferries when they are taken out of the timetable.
• Inner and fishing harbours — hull and deck readings on fishing vessels and traditional sailing ships lying alongside.

Protected waters, island links and the rules behind Harlingen gauging

Port state control in Harlingen is carried out by the Human Environment and Transport Inspectorate (ILT) within the Paris MoU, and foreign-flagged coasters calling here are inspected under the same regime as any ship in a Dutch port. Coasters tend to be older than the deep-sea fleet, built with box-shaped holds and pontoon or folding hatch covers, and an inspector boarding an elderly general cargo ship looks hard at the hatch covers, coamings and air pipes for wastage and holes. Gauging those items before arrival, rather than after a deficiency has been written, is one of the commonest requests from the managers of small cargo ships.

The island ferries bring their own pressures. They are domestic passenger ships that berth and unberth many times a day in all weathers, so shell plating, fendering, ramps and their hinges take repeated loads, and operators keep to tight maintenance schedules to avoid losing sailings. Because every ship approaching Harlingen crosses a protected sea, the authorities treat a leaking hull, a failed overboard line or a fuel spill in the Wadden Sea with particular seriousness. For managers of older coasters, that is one more reason to know the condition of the double bottom, the side shell and the fuel and ballast tanks before the ship is brought in on the tide.

Ships trading to Harlingen 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 Harlingen

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

The team normally lands at Amsterdam Schiphol and continues north by train or road; trains run to Harlingen by way of Leeuwarden, and Groningen Airport Eelde offers some European connections. The shipyard and the cargo quays have controlled access, so the ship's agent or the yard registers the technicians before they arrive. Our technicians travel from India on Schengen visas that must be applied for well ahead of the job; for a docking at the Harlingen yard the slot is usually fixed early enough to make that straightforward.

• 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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