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20 Maritime Reporter & Engineering News ? APRIL 2014 EYE ON DESIGNWhen Ulstein Sea of So-lutions (USOS) took part in a concept design competition for an arctic drillship, MARIN was asked to investi-gate the concept variations.USOS was asked to participate in a concept design competition for a drill-ship capable of operating in arctic con-ditions for several months a year. Special requirements are posed for the design of such a vessel due to the cold climate and the probability of encountering sea ice during operations. Instead of making adjustments to a conventional drillship design, USOS developed a completely new concept dedicated speciÞ cally to the purpose of the vessel. Each aspect of the design was subject to a sensitivity study in order to assess the impact of particular param-eters on the vessel design. Combining these design parameter sensitivities en-abled MARIN to draw conclusions for the optimal ship design.MARIN was involved in the design as-pects related to the hull. The goal of the sensitivity study was to give qualitative insight into the station keeping perfor- mance of the vessel when considering various concepts. Each concept used a disconnectable turret and had dynamic positioning (DP) capability, but the posi- tion of the turret varied between the con-cepts. Evaluation of the mooring loads, the required thrust and the DP watch circle revealed the best turret positions for a range of environmental conditions.Ice Þ eld in aNySIM With the aNySIM tool, a time domain simulation was conducted whereby hun-dreds of particles represented a managed (pre-broken by icebreakers) ice Þ eld. A number of parameters were given to de-scribe the severity of the ice conditions, including most importantly, the ice con- centration (the fraction of the total area covered by ice) and the average ice ß oe (particle) size. An algorithm based on Voronoi Tessellation was used to obtain a set of ice particles that exactly complied with the speciÞ ed parameter values. All concepts were tested for their ca-pabilities in the speciÞ c environmental conditions, evaluating four different vessel orientations with respect to the approaching ice Þ eld and for a black- out situation. Based on the results of these simulations, USOS could take an informed decision about the placement of the turret in the drillship. (USOS ap-proved publication of their concept de-sign test.)New Conept Under Test Arctic Drillship BY SOLANGE VAN DERWERFF The AuthorSolange van der Werff is project man- ager at the Trials & Monitoring depart- ment of MARIN, the Maritime Research Institute Netherlands. e: s.v.d.werff@marin.nl w: www.marin.nlMR #4 (18-25).indd 20MR #4 (18-25).indd 204/4/2014 10:31:26 AM4/4/2014 10:31:26 AM
