Load-out of a liftboat, Ras Al Kheimah, UAE
ALE has successfully transported, loaded-out and jacked-off a liftboat, weighing 5,800t, at Eversendai Offshore’s fabrication yard in Ras Al Kheimah, UAE.
ALE used 204 axle lines of SPMT in a configuration of 6 x 2 file 34 to perform the transportation and load-out of a liftboat. After the liftboat had been loaded-out, the liftboat’s legs were lowered onto the seabed. Then, on a falling tide, ALE simultaneously ballasted the barge, allowing the liftboat to be clear from the SPMTs and to be self-supporting.
Once the liftboat was clear, the SPMTs were removed from the barge so it could be removed from under the liftboat via a winching operation.
The weight and Centre of Gravity (COG) of the liftboat, combined with the capacity of the barge and the high quayside at site, severely restricted the suitable tides for the operation. The tide had to be closely monitored before ALE could perform the load-out, with a -300mm difference between the predicted and actual tides. Only three days per month had a strong enough tide to allow the operation to proceed. ALE executed a night load-out on the last possible tide of the month.
The load-out operation was fully controlled by ALE using deck-mounted movable ballast pumps onboard a class 330+ barge.
One of the challenges ALE faced was obtaining a suitable barge with a narrow deck, yet large enough ballast capacity suitable for the heavy weights involved.
The barge selected had a limited gap of just 140mm between the liftboat legs’ spudcans and the side of the barge. This meant the accuracy of trailer locations was strictly controlled, along with the removal of the barge via a winching operation being operated with extremely tight dimensional control.