Abstract
Loss of propulsion incidents are relatively common aboard large commercial vessels. While many loss of propulsion incidents resolve without further incident, they have the potential to lead to collisions and groundings which in turn can result in oil spills. As a result, loss of propulsion events have attracted the attention of many researchers and policy makers interested in preventing oil spills. While loss of propulsion events may be fairly common, they frequently are minor in nature because they either do not result in a full disabling of the vessel or the crew is able to regain propulsion relatively quickly. The objective of our research was to develop an accurate understanding of how often ships become fully disabled, and how long they may be without propulsion. This is an essential component to quantifying the oil spill risk presented by loss of propulsion events, and developing suitable prevention measures. Research on the topic has been difficult since data on self-repair times is not readily available from incident databases. As a result, existing work on the topic has relied on either expert elicitation or very small datasets. Our work identified a robust dataset of self-repair times, and produced a distribution of those times that can be used to estimate the potential duration of a loss of propulsion event. This work is part of a larger effort by the Washington State Department of Ecology to evaluate different approaches to reducing the oil spill risk potential of drift groundings in the Salish Sea.