Ultrasonic Gauging for Coasters, River-Sea Ships and Dredgers in Dordrecht

Inspection services for ships at Dordrecht

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

Seaport quays, Drechtsteden yards and lay berths

Gauging in and around Dordrecht takes place in three kinds of setting. At the seaport quays the work fits around a cargo operation, so holds are measured once discharged and ballast tanks once the crew has emptied and ventilated them. At the repair and conversion yards in Dordrecht and the neighbouring Drechtsteden towns, vessels are out of service with the yard's lifting gear, staging and services available, which allows a full programme to the TM plan with the class surveyor attending where a survey is due. And at lay berths along the rivers, idle coasters and workboats can be measured over several days at an unhurried pace.

The yards in this region are mostly built around inland vessels, dredgers, workboats and coastal ships rather than large deep-sea tonnage, and a manager chooses one according to the size of the vessel and the work needed. Larger short-sea ships needing a drydock usually go downriver to the Rotterdam area, Schiedam included. Inland tankers and dry-cargo barges also come out of the water in the Drechtsteden, and hull thickness readings are commonly part of their periodic certificate inspections. The same technicians and gauges serve both kinds of vessel, with the report laid out for whichever inspecting body will review it.

• Dordrecht seaport quays — hold, hatch coaming and tank-top gauging on coasters and short-sea ships between discharge and loading.
• Repair and conversion yards in the Drechtsteden — full thickness programmes on dredgers, workboats and coastal ships taken out of service.
• Lay berths on the Oude Maas and Merwede — owner's condition and pre-purchase gauging on idle river-sea coasters.
• Dredger maintenance periods — wear gauging on hoppers, bottom doors, suction pipes and discharge lines alongside the hull readings.
• Inland vessel docking and slipway periods — bottom and side plating readings for certificate renewals.
• Docks downriver at Schiedam and Rotterdam — where larger short-sea ships go, with Dordrecht readings feeding the steel plan.

Rules on the rivers: port state control, river-sea trading and EU measures

Seagoing ships at Dordrecht's quays are inspected under the Paris MoU, as in any Dutch port, and the coasters and river-sea ships that call are often older vessels flagged in the Netherlands, elsewhere in the EU or in the open registers. River-sea ships occupy a regulatory middle ground: on their seagoing legs they follow SOLAS and their class rules, while on the Rhine they sail under that river's navigation regulations as well. Their owners need hull condition data that satisfies the surveyor at one end of the voyage and stands up to an inspector at the other, and a single well-documented gauging serves both.

The EU's climate and recycling rules reach this fleet just as they reach ships at the coast: an Inventory of Hazardous Materials for ships calling at EU ports above the threshold tonnage, and emissions accounting under the EU ETS and FuelEU Maritime for the larger ships. For a small coaster fleet, though, the pressure comes as much from age and charterer expectations as from regulation. Dredging contractors set their own standards for fleet upkeep and plan structural work between campaigns, which is why Dordrecht's dredger work concentrates in the windows when vessels are back from a project and need to be ready for the next.

Ships trading to Dordrecht 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 Dordrecht

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

Dordrecht has a main-line rail station on the route between Rotterdam and Antwerp, so a team landing at Amsterdam Schiphol or Rotterdam The Hague Airport can reach the town by train or road. Yards and seaport terminals control their gates, and the ship's agent or the yard registers the technicians before arrival. Technicians from India travel on Schengen visas, so the docking date or the expected call should reach us early; for yard work we coordinate the start with the yard's schedule rather than with the ship's arrival alone.

• 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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