When should a vessel sound a single short blast of the whistle?

A vessel should sound a single short blast of the whistle when it intends to signal other vessels in a situation where it is passing another vessel. Specifically, this signal is made to communicate the intention to pass on the starboard side, which is the right side of the vessel when facing forward.

This signaling practice is grounded in maritime navigation rules, which are designed to promote safety and awareness on the water. In scenarios involving approaching vessels, clear communication through whistle signals helps to prevent confusion and potential collisions. Sounding one short blast conveys that the vessel is maneuvering in a specific way, allowing the other vessel to understand the intended action and respond accordingly if necessary.

In contrast, the other options describe different circumstances that do not properly correspond to the use of a single short blast. For instance, signaling for assistance typically requires a different sound pattern, while crossing ahead or leaving a dock involves distinct maneuvers that warrant their own specific whistle signals. This helps to establish a clear communication standard in maritime settings, ensuring all vessels can navigate safely.