Thickness Measurement for Ice-Class Ships at Umeå and the Kvarken Crossing

Inspection services for ships at Umeå

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

Where ships can be gauged at Umeå and Holmsund

Holmsund has cargo quays, an oil harbour and the ferry terminal, but no drydock for seagoing ships, so gauging here is done afloat. At the cargo quays, holds and ballast tanks can be measured during loading or discharge once the crew has prepared them. Tankers at the oil harbour follow terminal rules, and access is limited to spaces outside the cargo tanks. On the ferry, layovers at Holmsund allow machinery piping, accessible vehicle-deck plating and void spaces to be measured, but tanks and shell plating are best left to the planned yard period, when the ship is out of service.

Dockings for ships trading to Umeå take place at yards elsewhere, in Finland, Sweden or further around the Baltic, and are often timed for summer. The most useful local job before a docking is a spring scope on the ice belt and bow, carried out when the ship is alongside and the external shell is free of ice, so the yard can be told what to expect. Winter work at Holmsund is possible inside the ship at any time, but shell and open-deck work in mid-winter is slowed by cold and very short daylight, and plans should allow for ice delaying arrivals.

• Holmsund ferry terminal — machinery piping, vehicle deck and void-space readings on the Kvarken ro-pax during layovers.
• Cargo quays — hold, ballast tank and deck gauging on forest product carriers and general cargo ships during cargo work.
• Oil harbour — ballast tank, void and deck measurements on tankers during discharge, with terminal approval.
• Ice-belt and bow scopes alongside in spring — readings taken once the shell is clear of ice, before the summer docking.
• Docking yards in Finland and around the Baltic — completion of shell and tank programmes during the yard period.

Winter navigation rules and inspection at Umeå

Port state control at Umeå is carried out by the Swedish Transport Agency under the Paris MoU. Winter navigation in the Kvarken is managed jointly by Sweden and Finland: the Swedish Maritime Administration and its Finnish counterpart coordinate icebreaker assistance across the Gulf of Bothnia and publish traffic restrictions that set minimum ice classes and sizes for ships bound for ports such as Umeå. Because the Kvarken freezes early and hard, restrictions here usually apply for a long part of the winter, and a ship without an adequate ice class may simply not be assisted. For owners in these trades, the ice class on the certificate and the real condition of the ice belt both have to hold up.

The ferry link carries a particular weight. It is the only year-round crossing of the strait, so the operator has to fit maintenance and dockings around a timetable that the region depends on, and every day out of service is noticed on both sides. A ship working daily in ridged ice also accumulates structural wear at a rate that a winter or two of cargo voyages cannot match. Thickness measurement and crack detection on the bow, forefoot, ice belt and frames, compared year by year, give the operator and the class a clear trend, so that renewals can be planned for the yard rather than discovered during the season.

Ships trading to Umeå 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 Umeå

Most of the work on a Umeå job happens before the team boards: scope, plan and access are settled first, so the time on board goes on measurement.

Technicians usually fly to Stockholm Arlanda and connect on a domestic flight to Umeå Airport, from where Holmsund is reached by road. The team travels from India on Schengen visas, which also allow them to cross to Vaasa on the ferry or continue to a docking yard in Finland without a further visa. Access to the port and the ferry terminal is arranged by the ship's agent or the ferry operator. Winter jobs are planned with extra margin, because ice can delay ships and daylight is very short.

• 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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