Sailing into Wind Is Explained by Newtonian Mechanics Based on The Mass-Flow Rate

The physics of sailing into the wind can be explained using Newtonian mechanics based on the mass flow rate. The sail re-directs a mass of air each second (m/dt) towards the boat’s stern, at a relative velocity (dv) that depends on the apparent wind. The re-directed airflows push against the otherwise undisturbed apparent wind to create a backward force (i.e. Force = ma = m/dt × dv). The reaction generates an equal and opposite forward force that pushes the boat ahead. There are two separate airflows as the sail re-directs the wind on the sail’s windward and leeward sides. The leeward airflow relies on the Coanda effect and is sensitive to the sail’s angle-of-attack (AOA). This approach provides new and valuable insights on sailing into the wind. However, it is a very different approach compared to the current explanations of sailing into the wind, described by fluid mechanics and vector-based solutions.