Hull Thickness Gauging for Bornholm Ferries, Fast Craft and Offshore Wind Vessels in Rønne

Inspection services for ships at Rønne

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

Where ships are gauged at Rønne

The ferry berths at Rønne are worked hard. The catamarans turn round quickly between Ystad crossings and are best measured when they come off the route for maintenance, which operators normally schedule outside the summer season. The ro-pax ship on the Køge route has longer stays in Rønne, particularly overnight, and suits a defined scope of car-deck lanes, ramp structure and selected tanks. On the newer quays built for offshore wind, installation and heavy-lift vessels lie alongside during loading and between campaigns, and their open working decks and crane foundations can be reached directly from the quay or from the ship's own deck.

Bornholm has no large commercial dry dock, so full dockings of the ferries and of the wind-industry vessels are taken to yards on the mainland or abroad. Gauging at Rønne is therefore afloat work: deck, structure and tank readings on a ship lying in the harbour, ahead of a docking or between project campaigns. The island's fishing boats and small craft have slipway and workshop services in its harbours, but merchant ships needing hull work below the waterline go elsewhere. For a ship due to dock in Poland, Germany or Denmark soon after a Rønne call, readings taken on Bornholm give the yard and class a clear starting point.

• Ystad fast-ferry berths — hull plating, wet-deck and waterjet-room structure on aluminium catamarans withdrawn for maintenance outside the summer season.
• Køge ro-pax berth — car-deck, stern-ramp, ballast tank and piping gauging on the conventional ferry during overnight or planned lay-bys.
• Offshore wind quays and project areas — deck, crane-pedestal and sea-fastening structure on jack-up, heavy-lift and cable-lay vessels between campaigns.
• General cargo and bulk quays — hold, hatch-coaming and deck readings on coasters supplying the island.
• Cruise berth — machinery-space piping and open-deck plating on cruise ships during a summer day call.

Baltic rules, Bornholm's ferry contract and wind-farm work

Ships at Rønne are subject to Paris MoU port state control carried out by the Danish Maritime Authority, and the passenger ferries on regular services to Ystad, Køge and Sassnitz are also inspected under the EU regime for ro-ro passenger ships and high-speed craft. The Bornholm routes are run under a public service contract with the Danish state, which sets the timetable and capacity the operator must provide; that obligation is why ferry maintenance and docking are planned so carefully, and why gauging on these ships has to fit the operator's maintenance programme exactly. High-speed craft also follow the IMO High-Speed Craft Code, and their aluminium structure is surveyed against it and the class rules.

The southern Baltic is not usually ice-bound, but ships trading from Rønne towards northern ports in winter may carry Finnish-Swedish ice class notations, and the strengthened plating on those ships has its own minimum thicknesses. For the offshore wind vessels, the main driver of inspection is the work itself rather than port rules: jack-up legs, spudcans and leg wells, crane pedestals and the deck areas where turbine components are sea-fastened carry concentrated, repeated loads. Owners frequently want crack detection at welded attachments and readings on deck plating before a vessel moves to its next campaign, and a stay at Rønne between projects is a practical time to do it.

Ships trading to Rønne 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 Rønne

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

Bornholm Airport, just outside Rønne, has domestic flights from Copenhagen; the alternative is to travel via Copenhagen to Ystad and take the fast ferry across. Teams from India need Schengen visas, so dates for ferry maintenance periods or wind-vessel stays should be shared early. Access to the ferry terminal and the offshore wind quays is controlled, and the ship's agent or the operator arranges passes; project vessels may also require their own safety induction before the team boards.

• 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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