Minimum Time Sailing Boat Path Algorithm

Abstract

An iterative procedure to solve the nonlinear problem of fastest-path sailing vessel routing in an environment with variable winds and currents is proposed. In the routing of a sailing vessel, the primary control variable is the pointing (heading) of the vessel (assuming that the sails are chosen and trimmed optimally). Sailing vessel routing is highly nonlinear when considering environmental factors, such as winds and currents, and the behavior of the boat, given the weather conditions (i.e., polar diagrams that predict how fast one can sail, given the vessel's pointing relative to the true wind and the wind speed). The key algorithmic contribution of this article is a fastest-path algorithm for graphs with nonconvex edge costs that depend on weather, current, and boat polars. An illustrative scenario, with idealized weather attributes, and a real-world scenario, with parameters generated by numerical weather and current prediction models, are simulated and tested to compare the proposed algorithm against open-source routing software validated by active sailors. Preliminary results from the simulation setups tested are as follows: 1) the proposed sailing boat path algorithm is comparable to the open-source software available; and 2) exploiting the often unused but significant impactor of surface currents and incorporating leeway into sailing boat path planning enables higher fidelity guidance and faster (i.e., shorter time) routes, in comparing against the freely available baseline.