Question 39 ONC03 - Master LT 500-1600 GRT

The Correct Answer is C 1. **Explanation for Option C ("four to six seconds"):** The International Regulations for Preventing Collisions at Sea (COLREGs), Rule 32, defines the whistle signals. A "prolonged blast" is defined as a blast of from four to six seconds duration. This definition applies universally to all vessels referenced in the maneuvering and warning signal rules (including Rule 35, which covers fog signals for power-driven vessels). Therefore, the duration of a prolonged blast used by a power-driven vessel in fog, whether making way or not making way, is four to six seconds. 2. **Explanation of Incorrect Options:** * **A) about one second:** This duration defines a "short blast," which is used for maneuvering signals (e.g., changing course) but is not the specified duration for the primary fog signal (prolonged blast) of a power-driven vessel. * **B) two to four seconds:** This duration is neither a short blast (less than 1 second) nor a prolonged blast (four to six seconds); it does not correspond to any defined whistle blast duration in COLREGs. * **D) eight to ten seconds:** This duration is too long. While very long blasts are sometimes used in specific circumstances or by certain non-COLREG vessels, the internationally regulated definition of a prolonged blast is capped at six seconds.