Design of Truncated Mooring Line Model in KRISOs Deepwater Ocean Engineering Basin

Abstract

The present work have tried to investigate the applicability of the truncated mooring systems to the KRISO’s deep ocean engineering basin, DOEB with the ratio of 1:100, 1:60 and 1:50. The depth of the DOEB is 15m and therefore the corresponding truncated depth for this study were chosen to be equal to 1500m, 900m and 750m. The investigation was focused on both static and dynamic characteristics of the mooring system. It was shown, in the static pull out test, that the restoring force of a FPSO vessel could be modified to a good level of agreement for all three truncation cases. However, when the radius of the mooring site was reduced according to the trun-cation factor, the surge motion response during the free decay test showed a significant difference from the full depth model. However, the reduction of this discrepancy was achieved by increasing the radius up to its maxi-mum possible value with a consideration of the size of DOEB. Especially, in terms of the time period, the differ-ence was reduced from 24.0 to 5.3 seconds for truncation ratio of 1:100, 54.1 to 8.6 seconds for truncation ratio of 1:60, and 31.7 to 3.9 seconds for a truncation ratio of 1:50. As a results, the study verified the applicability of the truncated mooring system to the DOEB and therefore it could represent the full depth mooring system rela-tively well in the terms of static and dynamic condition.onding truncated depth for this study were chosen to be equal to 1500m, 900m and 750m. The investigation was focused on both static and dynamic characteristics of the mooring system. It was shown, in the static pull out test, that the restoring force of a FPSO vessel could be modified to a good level of agreement for all three truncation cases. However, when the radius of the mooring site was reduced according to the trun-cation factor, the surge motion response during the free decay test showed a significant difference from the full depth model. However, the reduction of this discrepancy was achieved by increasing the radius up to its maxi-mum possible value with a consideration of the size of DOEB. Especially, in terms of the time period, the differ-ence was reduced from 24.0 to 5.3 seconds for truncation ratio of 1:100, 54.1 to 8.6 seconds for truncation ratio of 1:60, and 31.7 to 3.9 seconds for a truncation ratio of 1:50. As a results, the study verified the applicability of the truncated mooring system to the DOEB and therefore it could represent the full depth mooring system rela-tively well in the terms of static and dynamic condition.