Floating vessel to crane barge lift trials

Amasus shipping, Conquest Offshore, and deugro Denmark A/S joined forces to perform feeder lifting trials offshore the Netherlands, the partners developing a plan for the installation of offshore windfarm components.

The unique approach of the plan sees the use of a standard offshore barge with a 1,500 tonne offshore crane (Conquest MB1) that will stay on location and will do the actual installation work on site, presently foundations and transition pieces only.

The supply of all heavy components from the fabrication yards will be carried out by ‘open-top’ cargo vessels (Abis Dublin or sister vessels). The design of these vessels enables large structures to be transported offshore in an ‘open top’ condition. The vessels are further fitted out with DP systems which enable offloading operations offshore without the added limitation and risk of mooring the vessel alongside the barge.

With this concept, the time lost transporting components on board the installation vessel from a nearby port is eliminated. The added advantage is that the feeder vessels can haul components from the actual fabrication sites instead of from a nearby feeder port.

The lifting trial was carried out in the Flushing/Westerscheldt area to prove the feasibility of offshore lifting operations from a free floating vessel to a crane barge.

Two approximately 200 tonne test weights were unloaded by heavy lift crane barge Conquest MB1, from the DP feeder vessel Abis Dublin. The test lifts were successfully performed in weather conditions with waves of 0.5m to 1.5m, wave periods of 2 to 9 seconds and wind speeds of 23 to 29 knots.

Siri Marine monitored and recorded all motions during the lifting trials, including wave induced vessel and barge motions, and especially heave motions of the vessel and the crane hook.

Conquest Offshore BV is a Dutch Joint Venture between Concordia Offshore and Zwagerman Offshore, which developed the newbuild 1,500 tonne offshore heavy lift crane barge, Conquest MB 1, equipped with an accurate and fully automated anti-heeling system and a free deck space of 3,700m² for 9,000 tons of cargo.