Offshore Weather Services provided weather forecasting services during the installation of Woodside’s North Rankin B platform. The North Rankin jacket was installed in September 2011 with the topsides installed by float over several months later in March-April 2012.
The North Rankin B topside float over was the heaviest ever conducted in the southern hemisphere and required the services of the world’s biggest barge the Heerema No 1.
Offshore weather services were engaged by Heerema Marine Contractors Ned BV to provide weather forecasting services during the project which also required an on-site consultant to provide daily briefings with the client, as well as issuing the site specific weather forecasts. In addition Heerema requested the model spectral data. Five sets of spectral wave data (each one produced from a different global or high resolution mesoscale atmospheric model) were uploaded to the client twice daily in order to run the client’s in house barge motion simulation software.
These simulations provided predictions of the motions and accelerations of the mating units of the North Rankin top sides to determine if the motions were within the limits acceptable to performing the float over operation. These predictions were then compared with measured data to provide increased confidence that the weather window for the operation was well within project limits.
Peter Wellby, Offshore Weather Services Operations Manager and Certified Consulting Meteorologist was the onsite Duty Forecaster during the Heerema operations and was based on the HLB Hermod during the jacket launch, upending and placement on the seafloor. It was a reunion of old friends as Peter had last stood on the Hermod some 30 years earlier when the heavy lift barge was working in the North Sea.