While underway and in sight of another vessel less than one half mile away, what must you sound if you put your engines on astern propulsion?

When a vessel is underway and operating in close proximity to another vessel, specific sound signals must be made to communicate maneuvers effectively. When you are putting your engines on astern propulsion, it is crucial to signal your intentions to nearby vessels.

The correct sound signal for indicating that your engines are being put into reverse is three short blasts of the whistle. This alert is essential, as it informs other vessels of your action, allowing them to understand that your boat is maneuvering in a manner that could affect their navigation safety. This sound is particularly important when vessels are in sight of each other and can help prevent collisions or misunderstandings about each vessel’s intentions.

In contrast, other sound signals have different meanings. For example, one long blast typically indicates that you are leaving a dock or a similar situation, while two long blasts indicate a change in direction. One short blast generally indicates that you intend to alter course to starboard. Each of these signals serves a unique purpose in maritime communication, making it clear to other vessels how you intend to navigate the waters.