Reliability of electro-hydraulic steering systems aboard commercial ships

For the purposes of this study, a generic electrohydraulic steering system of standard components similar to those found on currently sailing commercial tankers and freighters is considered. A fault tree analysis methodology is used to evaluate the proposed design and then employed to identify components or subsystems that have the most potential for improving overall system reliability. Design modifications consisting of parallel components of higher reliability are added to show the improvements in system availability. The study results show that complete regard for reliability criteria during the design process result in optimal availability while staying within design restrictions. Furthermore, regulatory agencies and classification societies could be using these same criteria when reviewing proposed design and new regulations on critical shipboard systems to increase vessel safety with minimal economic impact to the operators.