Deugro Denmark A/S, Conquest Offshore and Amasus Shipping/Abis Shipping have developed a plan for the installation of offshore windpark components. They will use a standard offshore barge with a 1500 tons offshore crane (Conquest MB1) that will stay on location and will do the actual installation work on site (at present foundations and transition pieces only).
Open Top
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/risk of mooring the vessel alongside the barge.
Time Gain
In this concept the time loss for 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.
Lifting Trials
The lifting trial has been carried out in the Flushing/Westerscheldt area in December 2012 to prove the feasibility of offshore lifting operations from a free floating vessel to a crane barge.
Two approximately 200 ton test weights were unloaded by heavy lift crane barge Conquest MB1, from the DP feeder vessel Abis Dublin. The test lifts was successfully performed in weather conditions with waves of 0.5 to 1.5 meter, waveperiods of 2 to 9 seconds and windspeeds of 23 to 29 knots (12 to 15 m/s. 6 to 7 beaufort).
Monitoring
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 MB 1
Conquest Offshore is a Dutch Joint Venture between Concordia Offshore and Zwagerman Offshore which developed the new built 1500 ton offshore heavy lift crane barge, Conquest MB 1, equipped with an accurate and fully automated anti-heeling system and a free deck space of 3700m² for 9000 tons of cargo.
The vessels in use during the lifting trials were:
Crane Barge Conquest MB 1
- Built 2012
- 136 x 36 m heavy duty barge
- Total free deck space for cargo 3700 m² for 9000 tons of cargo
- Deck strength of 20 ton/ m²
- Complete ballast and fully automatic anti heeling system
- 1500 metric ton revolving lifting capacity
- Dynamic Load System (DLS)
- 63-75 m (207-246 ft) heavy duty double boom
- 97-124 m (318-400 ft) long single boom
Abis Dublin
- Built 2012
- Single/Tween/Box/Open top
- DP1, del system L3, Speed: 12 knots
- DWT: 6000 metric tons
- LOA: 107,95 m, Beam: 16 m, Draught: 5,50 m
- Del 6x scania and place 3000KW / Scania / Diesel elect.
AHT Dutch Blue
- Built 2012
- Dimensions: 52,80 m x 13,20 m x 5,20 m
- Draught: 4,50 m
- Service speed: 11,5 knots
- Bollard pull: 50 – 54 metric tons
- Capacity: 37 persons
The equipment in use during the lifting trials were:
- Cranemaster heave compensator in crane hook
- AH industries C/T winches for control of the weights during lifting
- Siri Marine motion monitoring sensors and Marine position / surface navigation system (Orca Pilot + DGPS compass)
