What is the potential of using ship fatigue routing in terms of fatigue life extension?

Paper in proceeding, 2012

Fatigue damage accumulation in ship structures is a continuous random process, which together with several sources of uncertainties in the fatigue analysis make the fatigue life prediction complex and difficult. It may be a plausible explanation to why fatigue cracks are found earlier than expected in many ocean-crossing vessels. The existence of fatigue cracks brings great challenges to the safety of ship structures, maintenance issues and costs. Various means should therefore be implemented to extend ships’ fatigue service life, for example, decrease cargo loadings and reduce ship speeds. Another alternative is to employ a ship routing design which can reduce/minimize the fatigue damage accumulation, denoted as ship fatigue routing here. This investigation presents a ship fatigue routing procedure, using a simple spectral method developed by the authors, and the analysis of long-term fatigue assessment of a typical container vessel. The potential benefits of using the proposed ship fatigue routing procedure is demonstrated by a case study of a 2,800TEU container ship, using data from full-scale measurements, hindcast data and numerical analysis. It is found that, at least for the current vessel, the fatigue life can be extended by at least 50% by choosing more well-suited “optimum” ship routings.