Question 39 OSV01 - Master/Chief Mate - Offshore Supply Vessels

The Correct Answer is C 1. **Explanation for Option C ("four to six seconds"):** The Rules of the Road (specifically, COLREGs Rule 32 and associated Annex III, Section 1(a)) define the characteristics of sound signals. A "prolonged blast" is defined as a blast of **four to six seconds' duration**. This definition applies universally under both the International and Inland Rules for any vessel required to use this specific signal component (such as the fog signals for a power-driven vessel). 2. **Why the other options are incorrect:** * **A) about one second:** This duration defines a "short blast," which is used in maneuvering and warning signals (Rule 34), not as the duration for a prolonged blast in fog (Rule 35). * **B) two to four seconds:** This range is too short. While it overlaps slightly with the required lower limit, it does not match the official regulatory definition (4–6 seconds). * **D) eight to ten seconds:** This duration is too long. While the rules do not strictly prohibit very long blasts, the defined prolonged blast used in mandatory fog signals must fall within the 4-to-6 second range.