Survivability of an Ocean Patrol Vessels -Analysis approach and uncertainty treatment.
Survivability of an Ocean Patrol Vessel -Analysis approach and uncertainty treatment AbstractMilitary Ocean Patrol Vessels (OPVs) are today an increasingly common type of naval ship. To facilitate the wide range of tasks with small crews, OPVs represent several ship design compromises between, for example, survivability, redundancy and technical endurance, and some of these compromises are new to military ships. The aim of this study is to examine how the design risk control-options in relation to survivability, redundancy and technical endurance can be linked to the operational risk in a patrol and surveillance scenario. The ship operation for a generic OPV, including the actions of the threat, is modelled with a Bayesian network describing the scenario and the dependency among different influences. The scenario is described with expert data collected from subject matter experts. The approach includes an analysis of uncertainty using Monte Carlo analysis and numerical derivative analysis. The results show that it is possible to link the performance of specific ship design features to the operational risk. Being able to propagate the epistemic uncertainties through the model is important to understand how the uncertainty in the input affects the output and the output uncertainty for the studied case is small relative to the input uncertainty. The study shows that linking different ship design features for aspects such as survivability, redundancy and technical endurance to the operational risk gives important information for the ship design decision-making process.
Keywords: risk control options; ocean patrol vessel; survivability; uncertainty analysis; influence diagram
IntroductionThe risk control options for achieving security and survivability for naval ships are aspects that are often connected to central aspects of the ship design, such as damage stability and system redundancy. When the basic design is set, the possibility of changing the ship's survivability is limited. Therefore, there is a need to assess the level of survivability at early stages of the ship design to provide input to the decision process regarding risk control options. Such an assessment is especially challenging when the threats envisioned are new and the survivability design of older ships is not a relevant benchmark. This work presents a framework for decision analyses where both the operational risk and the uncertainty of the assessment are studied.Comprehensive studies on ship security risk analysis are rare [1,2], and the systematic handling of the uncertainties needed to create rational input for the decision-making process is even rarer. There is a need for a deeper understanding of ship security analysis and how ship security analysis can incorporate uncertainties as an important part of the risk picture. In a study of risk analysis for a piracy case, Liwång and Ringsberg [2] document expert uncertainty and how it can be reduced in relatio...