Energy Efficient Self-Steering Mechanism for an Autonomous Sailing Vessel

This paper presents the development and experimental evaluation of a self-steering mechanism for an autonomous sailing vessel. The steering mechanism is designed and tailored to relief the commonly used electro-mechanical steering during majority of the mission by the use of pure mechanical coupling between the self-trimming rig and the rudder. This significantly reduces the need for electric power for steering at constant apparent wind angle. Added to the steering, a two-layer navigation system is proposed for path-planning and navigation with algorithms tailored for low-power, low-memory microcontroller. We present experimental results from a total of 19 days of autonomous sailing in Stockholm's Archipelago. The experiments enabled us to compare the sailing performance with both active and self-steering systems for different apparent wind angles. On average, the active steering keeps a heading within ±5.1° of the target while the self-steering is able to maintain the heading within ±8.1° of the target. Another conclusion that can be drawn is that the apparent wind angle doesn't influence the steering performance.