The World’s Heaviest Ship Lifts Oil Platforms Without A Single Crane

Pioneering Spirit is a single-lift heavy construction vessel owned by Swiss offshore contractor Allseas. At its deepest operational draught of 27 metres, the vessel displaces approximately 900,000 tonnes of seawater, making it the heaviest object ever set afloat at sea. At 403,342 gross tonnes, it is also the largest vessel ever constructed by gross tonnage.

Pioneering Spirit is 382 metres long and 124 metres wide. It is powered by eight diesel generators producing a combined 95 MW, driving 12 azimuth thrusters that give it a top speed of 14 knots and DP3-class dynamic positioning capability. Accommodation is provided for up to 571 personnel.

Pioneering Spirit was designed and built to perform a task no other vessel has been able to carry out at this scale: the single-lift installation and removal of offshore oil and gas platform topsides and jackets, and the installation of record-weight subsea pipelines.

Design and Construction

The vessel was designed entirely in-house by Allseas. Construction was carried out by Daewoo Shipbuilding & Marine Engineering (now Hanwha Ocean) in South Korea, with the main hull construction contract signed in June 2010. The vessel departed the DSME yard in November 2014, arrived at the Port of Rotterdam in January 2015 for completion and commissioning, and entered offshore service in August 2016.

The construction cost of the vessel was approximately € 2.6 billion. The vessel was originally named Pieter Schelte, after the father of Allseas founder Edward Heerema. The name was changed to Pioneering Spirit in February 2015 following concerns about the original namesake’s wartime history.

Midway through construction, Allseas widened the hull by 6.75 metres to increase clearance between the bows and the legs of large offshore platforms. This increased the overall beam from 117 metres to 124 metres, and the bow slot width from 52 metres to 59 metres.

The Topsides Lift System

The primary record-breaking feature of Pioneering Spirit is its Topsides Lift System (TLS), located at the bow. The bow is cut into a U-shaped slot measuring 122 metres in length and 59 metres wide, large enough to accommodate the legs of a large offshore platform.

To perform a single-lift topsides removal, the vessel reverses into position until the platform legs sit inside the bow slot. Eight horizontal steel lifting beams then extend across the slot and position themselves directly beneath the topsides — the upper section of an offshore platform, which houses the drilling equipment, process modules, and crew accommodation.

The vessel then uses its ballast system to lower itself, drawing in seawater until the lifting beams are positioned just beneath the underside of the topsides load. At the calculated moment, the topsides connections to the supporting structure below are severed. The ballast system then rapidly expels the seawater, raising the hull and transferring the load from the platform’s legs to the vessel’s lifting beams in a single controlled motion.

The actual transfer of load takes seconds. The removal of the 15,300-tonne Heather Alpha topsides from the UK North Sea in 2025 was completed in approximately 14 seconds. The operation requires years of engineering preparation and platform-specific modelling before the lift day.

A motion compensation system is integrated into the TLS to counteract the effects of wave action throughout the lift, which is carried out in open sea conditions.

Records

In July 2024, Pioneering Spirit performed the heaviest offshore lift ever recorded. The vessel removed the topsides of Shell’s Brent Charlie platform from the UK North Sea in a single lift, with the topsides weighing 31,000 tonnes. The previous record was held by the same vessel: the Brent Delta topsides removal in April 2017, at 24,200 tonnes.

Between 2017 and 2024, Pioneering Spirit removed all four topsides from Shell’s Brent field in the UK North Sea. The combined weight of the four lifts totalled approximately 100,000 tonnes, with the majority of the recovered steel subsequently recycled at Able UK’s Seaton Port facility in Hartlepool.

For comparison, Big Carl, the largest land-based crane currently in operation, used for reactor dome installation at the Hinkley Point C nuclear power station, is rated to lift approximately 5,000 tonnes. The Brent Charlie lift was six times heavier.

The Jacket Lift System

A second lifting system was installed on Pioneering Spirit’s stern in September 2021. The Jacket Lift System (JLS) consists of two 170-metre lifting beams weighing 6,500 tonnes, designed to remove or install offshore platform jackets — the lattice steel substructures connecting the topsides to the seabed- in a single lift up to 20,000 tonnes.

This installation made Pioneering Spirit the world’s largest floating sheerleg. The JLS’s first operational lift took place in April 2022, with the removal of CNR International’s Ninian Northern jacket from the North Sea at 8,100 tonnes.

Pipeline Operations

In addition to platform installation and removal, Pioneering Spirit is also the world’s most capable pipelay vessel. It has an S-lay tension capacity of 2,000 tonnes, double that of its nearest rival, and can install pipelines across a diameter range of 6 to 68 inches at water depths exceeding 4,000 metres.

The vessel carries up to 27,000 tonnes of pipe cargo and is equipped with a double-joint factory, six welding stations, and a continuous main firing line of 260 metres.

Offshore Decommissioning Context

The operational context for Pioneering Spirit is the progressive decommissioning of the first generation of North Sea oil and gas platforms, most of which were installed in the 1970s and 1980s and have now reached or are approaching the end of their productive lives.

The traditional method of offshore platform removal involves cutting the structure into sections at sea and transporting the pieces to shore over an extended period. Single-lift removal by Pioneering Spirit transfers the entire topsides intact to port, where dismantling and recycling are carried out onshore under controlled conditions. This reduces offshore exposure time, cost, and risk to personnel.

The same single-lift method is also applicable to the installation and removal of large offshore wind farm substations, which can weigh up to 30,000 tonnes, placing them within the vessel’s operating range.

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