Motion AnalysisDrilling Tender B, a sister vessel to A was about to be launched when the operability problems were noticed for A. The Crane capacity of the vessel was upgraded keeping the same dimensions. The vessel’s lightship weight has also unexpectedly gone up by around 1,500t and caused serious apprehensions about the vessels performance.
A different FEED study was necessitated as the lightship weight had gone up and the study became very complicated as there was no leeway on the draft.
The study revealed that similar solutions as on Tender A of providing Controlled flooding tanks offered a solution.
However as the vessel was committed to a charter an alternate quick fix even though less efficient solution was also provided to the Owners.
- Merging Port and Starboard ballast tanks at either ends of the vessel to convert them to Free Surface Anti Roll Tanks
- Opening the Center Line Bulkhead partitioning the tanks shall do the modification
- The roll damping to be induced by means of the internal waves and the tank to be tuned to the sea state’s fundamental frequency by varying the filling level