Alpha factors for the calculation of forecasted operational limits for marine operations in the Barents Sea

• Main Author: Wilcken, Sara
• Format: Master Thesis
• Language: English
• Published: University of Stavanger, Norway 2012
• Subjects: offshore teknologi; undervannsteknologi; weather forecast uncertainty; polar low; Barents Sea; alpha factor; marine operation; VDP::Technology: 500::Marine technology: 580::Offshore technology: 581; Norwegian Sea
• Online Access: http://hdl.handle.net/11250/182992

Master's thesis in Offshore technology The execution of marine operations often depends on the wave heights being low enough for safe operations. This needs to be the case for the time the operation takes. Weather forecasts are used to predict the wave heights. Uncertainties are connected to weather forecasts and higher wave heights than expected during a marine operation can potentially lead to accidents. Thus Det Norske Veritas introduced the so called “alpha factors” for the North and Norwegian Sea in its standard for Marine Operations ([1], [18]). Alpha factors downgrade the operational wave height limit to a forecasted operational wave height limit to take care of the weather forecast uncertainty in these areas. This thesis explains the calculation as well as the use of the alpha factor. Comparisons to how other standards and guidelines treat the weather forecast uncertainty are drawn. Due to potentially more marine operations in the Barents Sea in the near future it is discussed how to take care of the weather forecast uncertainty in this region. Alpha factors for the Barents Sea are calculated. They indicate that the weather forecast uncertainty is bigger in the Barents Sea than further south. The small scale storms that are characteristic to Polar Regions called “polar lows” are described: These are threats to marine operations in the Barents Sea. Alpha factors are not sufficient to take care of the forecast uncertainty connected to polar lows. Thus the suggestion is made that the polar low probability forecast should be a requirement for the execution of marine operations in the Barents Sea.