The ultimate marine lift

18 September 2014


Stephen Powney looks at the use of a special mobile marine crane in the refloating operation of stricken cruise ship Costa Concordia.

When it comes to maritime salvage projects they don't come any bigger than the cruise ship Costa Concordia, which tragically hit rocks and capsized off the coast of Italy in 2012 with the loss of 32 lives.

The project to successfully turn the vessel upright, refloat it and tow to Genoa port has recently been completed and is already being widely-regarded as one of the largest salvage jobs in maritime history, with total salvage costs expected to reach around €1.5bn.

The numbers are mind-boggling. The Costa Concordia is twice as big as the Titanic at 114,137GT and is 290m in length. The heavy-lift work involved in such a project was always going to involve some serious equipment.

American-owned Titan Salvage and Italian marine contractor Micoperi were awarded the project to remove the ship from off Giglio Island.

One of the cranes brought in to perform vital lifting work installing sponsons - giant tanks to help refloat the vessel - was from Conquest Offshore BV.

For Conquest, a joint venture between Concordia Offshore BV, Paul van Es Holding BV and Zwagerman Offshore Services BV for offshore heavy lift activities, it was a case of being in the right place at the right time with the correct crane.

The Conquest MB 1 heavy lift crane barge with Spacelift MC 35000 DLS mobile marine crane, designed by Zwagerman, was already in production when the company became involved in talks on participating in the salvage project.

Conquest's operations manager Floris Bomers said: "By coincidence, it was operational just in time to assist in the mega job."

The modular-designed barge, outfitted with an operational sixpoint mooring system from ACE and accommodation modules suitable for 60 workers, left Flushing harbour in the Netherlands and arrived in Italy on April 8-10, reaching the scene at Giglio Island on April 21.

Barge deck area extends to 36x136m, with a free deck space of 3,700s sqm featuring a strong 20t/ sqm deck area and a very shallow working depth (3.5m).

The fully rotating 1,400t Spacelift MC 350000 DLS crane with Dynamic Load System (DLS) is mounted on a pedestal foundation with a self-supporting foot frame and associated fully automated heel/trim compensation system. The crane is not integrated into the barge's structure and is therefore moveable.

Bomers said: "The uniqueness of the crane is not in use of certain components, but it's the way all the components come together. We have a large barge with a strong deck area with a revolving heavy lift crane which can act in a fairly shallow area."

Equipped with a complete ballast (9,600 cubic metres per hour capacity) and fully-automated anti-heeling system, the sophisticated rotating/luffing crane was tasked with lifting 19 sponsons into position on the ship's sides - 15 on the starboard side and four on the port side - after the ship had already been successfully uprighted. The sponsons, the heaviest of which was 850t, are filled with seawater and then emptied during the refloating operation to lift the vessel.

The DLS, designed to improve the load capacity of the crane, has a 1,000t capacity and the counterweight is 450t. Four hydraulic jack cylinders on the back of the crane are placed with bogies on an 18m-diameter ring. The cylinders pull when a load is lifted and push when the crane is stationary to balance the counterweight.

Together with the base structure of the crane, this generates enough moment of force to perform the heavy lifts required.

Bomers added: "With this design, we reduce the ring bearing moment and we are minimising the wear and tear on the bearing. This is a unique feature."

Other crane features include a 63-75m heavy-duty main double boom (with additional 12m hoistbeam) or up to 130m as a single boom. Boom length was adjustable according to the lifting requirements.

"The crane is a 100% Dutch engineered and constructed product, and electronically-driven, whereby 30% of the energy is recovered by a power recovery system when lowering the load."

The main hoist has two 630kW winches (90m/min) together generating a maximum lifting speed of 1.5m/sec, while the two boomhoist wires and two main hook wires are 44mm x 1600m. The swing system is powered by 8x22kW motors operated through 2x2x2x2 left-right switch basis with a swing speed of 1-degree/sec, giving a 360-degree rotation speed of 6min.

Without the 360-degree action, Bomers said the job would have been close to impossible.

The crane is powered by two Caterpillar D3508 diesel engines.

"This project puts us on the map. The company is relatively young, but participating companies have a proven track record of success in the marine and offshore industry.

"The Costa Concordia salvage job, as a total project with the lifting and installation of the sponsons up to 850t, with no recorded downtime is extraordinary for a newly-designed crane. We are very proud that we were able to contribute to one of the biggest salvage projects known to date."

Conquest's part of the project took three and-a-half months. About 12 Conquest employees were on the barge, but a much wider team, including divers were also working from the platform. After lifting operations, the Conquest MB 1 was towed to a nearby port and on standby while the Costa Concordia was towed to Genoa.