Vessel Location Modeling for Maritime Search and Rescue

The location-allocation problem serves to deploy assets effectively to respond to a known or estimated geographically distributed demand for service, including providing emergency services. At first glance, the rescue vessel location problem in the Search and Rescue (SAR) domain is similar to the emergency vehicle location problem such as for ambulance location. In both cases, mathematical location models can be formulated to maximize the number of incidents that can be serviced by a specified number of resources (vehicles) within a pre-specified amount of time, or, alternatively, we can minimize the time it would take a vehicle to arrive at the scene of the incident. However, several differences exist. First of all, in the case of emergency vehicle location, all response units are generally assumed to have the same capability and speed. Conversely, the Canadian Coast Guard (CCG) has many different SAR rescue vessel types that were designed or purchased with specific tasks in mind, and not all are equally effective at handling different incident types. Also, the ranges vary greatly among different types of rescue vessels, so rescue vessel capabilities need to be considered in our study. Furthermore, the method of computing distances to the incidents is different as rescue vessels are patrolling on the sea, thus requiring a land-avoidance algorithm to calculate the travel distance rather than Euclidean or Manhattan distance metrics. However, land-avoidance distance is calculated before performing the optimization in this study, so this distinction is moot in this instance.