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October 2012 www.sname.org/sname/mt support structure, moorings, and export elec- trical cables in an integrated simulation model for global performance analyses. The case studies included fully-cou- pled aero-hydro-servo-elastic analysis of the integrated turbine rotor nacelle assem- bly and its control system, oating support structure, and stationkeeping systems. Parametric studies evaluated the relative importance of various design parameters, including the site location; the return period and directionality of environmental con- ditions; the turbine operating modes; the hurricane wind models; and the eect of fault conditions in both the turbineĀs nacelle yaw control system and blade pitch control system. Case study results indicate FOWTs are technically viable for the OCS, but there are several issues that bear addressing. First, unlike bottom-founded oshore wind turbines, the sensitivity of FOWT global responses to the return period of extreme storm conditions mostly falls into a rather narrow scattering band. With the assumption that FOWTs have a low risk of causing loss of human life and envi- ronmental pollution, the 50-year return storm design requirement appears to be a rational criterion for hurricane prone areas on the OCS. Second, special care should be taken in select- ing the critical load combinations, as these vary depending on the site-specic environment, the water depth, and the type of oater. And nally, the design considerations for single or smaller number of prototype FOWTs could be dierent from those for a full-scale +100 MW farm of FOWTs. Clearly, more research is warranted. e hope is that the work ABS has carried out thus far will be a solid foundation for future studies. MTLars Samuelsson is a manager in the Energy Develop- ment group at ABS and has more than 15 years of ex- perience in oshore structures. Qing Yu is a managing principal engineer in ABS Corporate Technology, where he is responsible for research and development relating to oshore renewable energy. (603) 625 - 8639 EXT 14 www.upnovr.com Vertical ladders Incline ladders Battens Treads Grating Jacobs ladders Commercial gangways NAVSEA gangways Truss brows Fiberglass Brows Accommodation Ladder Systems