Research Plan for the Investigation of Injury and Fatigue Criteria for High Performance Craft

Recently developed injury and fatigue criteria hold the promise of providing high performance craft with improved safety characteristics while operating in a seaway. The ISO 2631 Part 5 daily equivalent static compression stress dose to the spine, normalized to an exposure dose of 8 hours or “Sed(8)” criteria has been proposed and accepted as an injury model. Epidemiology is currently being gathered using the CACTUs II system as described in [Petersen at al 2008] which should correlate Sed(8) measurements with long term injury reports. Impact Count Index or “ICI” has been proposed as a potential metric for motion induced fatigue. Limited testing and measurement has been performed which has led to proposed criteria for minimizing motion induced fatigue. These criteria can be used to evaluate existing high performance craft through full scale trials. However, significant work is needed to quickly assess early design decisions with regard to these criteria. Fundamental craft characteristics are decided early in the design process. The ramifications of these decisions with respect to these criteria are not clearly understood. The effect of the operational environment on the performance of a given craft with regard to these criteria is also not clearly understood. Thus, in order to truly protect operators of high speed craft in a variety of sea states and operational conditions, further understanding of the response of a given design to a wide variety of sea conditions is needed. The primary objective of this paper is to focus attention on this design problem, describe these criteria and present a long-range research plan that will lead to the definition of operability envelopes in a seaway for high performance craft.