UTM for Offshore Energy Vessels and Cargo Ships at Great Yarmouth

Inspection services for ships at Great Yarmouth

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

Gauging berths in the river and the outer harbour

The outer harbour is where large offshore vessels and jack-ups lie between campaigns, and its quays are open, with room for a vehicle carrying equipment and straightforward access to the vessel's deck. The river berths are tighter. The quays on both banks are long-established and well sheltered from the sea, but the current through the harbour is strong, so a ship's gangway and moorings need tending through each tide while the team works on board. Vessels that need docking go elsewhere: smaller craft often to Lowestoft, a short way down the coast, where there is a dry dock with slipways, and larger offshore vessels and cargo ships to yards in other British ports or on the Continent.

Offshore vessels bring their own access questions. Supply ships carry drilling mud, brine, fuel and water in tanks below deck, so tank entry depends on what the tank last held, how it has been cleaned and gas-freed, and an enclosed-space permit issued under the vessel's own system. Crew transfer vessels are usually aluminium catamarans, which calls for the gauge to be set and checked for the alloy rather than steel. On jack-ups, the preload tanks and the structure around the legs are the areas owners most often ask about, and access is planned with the crew because the legs and their jacking systems are working machinery.

• Outer harbour quays: hull, deck and preload tank gauging on jack-up installation vessels and service operation vessels between campaigns.
• River berths on the Yare: supply ship and standby vessel tank, deck and cargo-rail readings during port turnarounds.
• Crew transfer vessel berths: bottom and side plating checks on aluminium catamarans, with the gauge set for the alloy.
• Cargo quays in the river and outer harbour: hold and hatch cover gauging on coasters working bulk and project cargoes.
• Lowestoft dry dock and slipways, a short way south: where smaller offshore craft go for the repairs that Great Yarmouth readings identify.

Offshore vetting, port state control and an energy coast in transition

Foreign-flagged cargo ships at Great Yarmouth come under the Maritime and Coastguard Agency's port state control, which the UK operates in line with the Paris MoU. Many of the offshore vessels working from the port, though, are examined less often by port state control than by their charterers, through OCIMF's Offshore Vessel Inspection Database and the operators' own vetting against industry guidance for offshore marine operations. Those inspectors look at much of the structure a class surveyor would, and one who finds a wasted deck, a weeping tank or a corroded fire main will want to see thickness evidence before the vessel goes back on hire.

The shift from gas to wind changes the fleet as well as the cargo. Supply ships and standby vessels built for the gas fields are reaching ages at which renewal surveys reveal steel work, and owners are deciding whether to invest, convert a vessel for wind farm service or sell her. Newer service operation vessels often have hybrid power and motion-compensated walk-to-work gangways, but their hulls, ballast tanks and sea chests corrode like any other ship's, and a vessel that stays offshore for weeks gives few chances to look at them. Gauging during a port call lets the technical manager follow that structure between dockings.

Ships trading to Great Yarmouth 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 Great Yarmouth

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

The team normally flies into London Heathrow or Stansted and continues to Norfolk by rail or road; Norwich Airport, which also handles offshore helicopter traffic, is the nearest airport but has few international routes. The technicians travel from India on UK visas, so for offshore vessels we ask for a range of likely port days rather than a single date. Access to the outer harbour and the river quays is controlled, and the vessel's agent or the operator's marine coordinator arranges passes against each technician's passport and confirms the berth.

• 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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