Your power-driven vessel is underway when you sight a sailing vessel on your port bow. Which vessel is the "stand-on" vessel?

Answer: A — The sailing vessel, as it is under sail

The sailing vessel is considered the "stand-on" vessel in this situation because vessels under sail generally have the right of way in encounters with power-driven vessels. According to the International Regulations for Preventing Collisions at Sea (COLREGs), when a sailing vessel is under sail, it is entitled to maintain its course and speed. In this scenario, your power-driven vessel is approaching the sailing vessel on a port bow, which means it is necessary for your vessel to take action to avoid a collision. While larger vessels have more maneuverability, in this context, it is the type of vessel and its method of operation that determine which has the right of way. Therefore, the sailing vessel's operation under sail gives it the priority as the stand-on vessel. This regulation is designed to enhance safety on the water and ensure that vessels using alternative means of propulsion, like sails, can navigate without unnecessary disturbance from power-driven vessels.