Vessel Drift and Response Analysis for Canada’s Pacific Coast

This study, commissioned by Clear Seas and produced by Nuka Research and Planning Group, LLC, analyzes how ship routing combined with the location and availability of Emergency Tow Vessels (ETVs) or rescue tugs might affect the probability of a disabled vessel drifting aground along the Pacific coast of Canada. The report summarizes the outcomes of a scenario-based vessel drift and response analysis and is the first of three studies in the Marine Transportation Corridors project.

The study uses seven scenarios to reflect the locations of current and potential future rescue tugs. The parameters that define the different scenarios were developed in consultation with Clear Seas and regional representatives of Environment and Climate Change Canada, the Canadian Coast Guard, Transport Canada, and the British Columbia Coast Pilots.

Each of the scenarios was run through a model to estimate the probability that a rescue tug would arrive in time to assist a disabled vessel. The model incorporates the coastline and historical wind conditions in the area and the time needed for a tug to reach the disabled vessel, which was calculated based on the tug’s starting location, mobilization time, travel speed, route, and time to establish a tow line. The disabled vessel’s drifting time before grounding was calculated based on drift characteristics of particular vessel sizes and types that commonly transit the area, combined with wind conditions drawn from historical wind data. Like all models, it is a simplified approximation of a complex system and the model’s limits must be considered when interpreting and applying the results.

This report seeks to increase decision-makers’ understanding of the role that ship routing and capable, strategically-located, and promptly-deployed rescue tugs can play in reducing risks associated with shipping traffic in western Canadian waters. The results presented in this report may be applied to risk mitigation decisions, such as the optimal location for rescue tugs or other proactive vessel management measures to reduce the risks associated with drifting vessels along Canada’s Pacific coast.

This study is the first of three to be presented by Clear Seas as elements of the Marine Transportation Corridors project. The other two studies include: (1) a multi-year marine traffic analysis using Automatic Identification System (AIS) data; and (2) the identification of sensitive areas on Canada’s Pacific coast. The results of the three studies will be layered and analyzed to enhance the understanding of some of the risks and potential prevention strategies associated with shipping activity in the region.