By using StormGeo and Deep Sea Mooring’s Response Forecasting Service, Safe Zephyrus Increased Gangway Connectivity by two per cent.
One of the most important tasks for offshore accommodation vessels (flotels) today is providing a safe passage for personnel to the host installation. In such cases, the accommodation vessels are positioned alongside the rig and connected by means of a telescopic gangway.
Yet, despite the latest dynamic positioning (DP) systems on the accommodation vessels, unpredictable weather and the understandable need to err on the side of caution means that in questionable conditions where there is extreme weather, for example, such gangways are sometimes non-operational.
“Historically the decision on whether or not to connect the gangway has been down to the seamanship of the team on board who operate according to a specific guidelines,” said Captain James Suffield, Master & Offshore Installation Manager of the Safe Zephyrus accommodation vessel.
“These include a free range of heading movement of around 90 degrees and a maximum telescopic movement of the gangway of no more than +/- seven meters before disconnection is required.”
Yet, what if you could estimate the movement of the vessel based on the latest weather forecasts and highly accurate predictions on how such floating units will respond?
Such a scenario is becoming a reality through an innovative partnership between StormGeo and Deep Sea Mooring (DSM), the leading provider of offshore mooring services in Norway.
StormGeo combines state-of-the art technologies from meteorology and hydrodynamics to accurately predict the relative movement of the flotel and the gangway stroke to the attached platform. The result is the ability to forecast gangway motion, maximize availability, optimize and safeguard operations.
Whereas previously in marginal weather states we have perhaps disconnected too early, we now have the necessary information to optimize connectivity while still adhering to the highest safety standards.Captain Suffield
One such pilot is taking place on Prosafe’s Safe Zephyrus, the world’s most advanced and versatile semi-submersible accommodation units capable of operating in the harshest environments and to the highest standards of safety.
The vessel is equipped with a DP3 system, can accommodate 450 persons, and is currently supporting Aker BP (formerly Det norske oljeselskap ASA) in the Ivar Aasen Project field in the Norwegian sector of the North Sea. The field is 100 miles south west of Stavanger in harsh offshore conditions (especially in winter) where wave height is rarely below four meters.
Captain Suffield continues: “The predictive software and DSM’s engineering expertise has been very helpful to us in determining the best heading and optimal loading required to maintain gangway connections. Whereas previously in marginal weather states, we have perhaps disconnected too early, now we have the necessary information to optimize connectivity while still adhering to the highest safety standards.”
The result is that over just two months, gangway connectivity has increased by an extra two per cent compared to previously. Taking into account that the Safe Zephyrus houses 450 personnel - all on high day rates - as well as the separate rig and vessel hire costs, the increased connectivity is leading to substantial cost savings.
The knowledge-based information generated from StormGeo and DSM is also very useful in helping plan longer-term support vessel operations. Captain Suffield again: “The information allows us to change heading when required and is particularly useful when simultaneous support and supply boat operations are taking place. The result is more efficient operations.”
And there is more to come. Captain Suffield concludes: “We are continuing to fine-tune the information we receive and combining it with other hydrodynamics and power management data to even better predict vessel movement. Supporting helicopter logistics is also an option as well. What is clear to us so far, however, is that the forecasting system provides significant potential for operators.”
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