What signal indicates a vessel's intention to alter course to port?

The correct signal indicating a vessel's intention to alter course to port is represented by the two short blasts. This is an essential part of maritime communication, particularly under the International Regulations for Preventing Collisions at Sea (COLREGs). When a vessel intends to change its course to port, it utilizes two short blasts on its whistle to communicate this intention to other vessels nearby. It helps ensure that other navigators are aware of the maneuver, promoting safety and preventing collisions.

Understanding the significance of these signals is crucial for effective navigation and communication on the water. The other options represent different signals: one long blast signals an intention to alter course to starboard, while three short flashes and one short blast denote other actions that do not pertain to changing course to port.