Question 19 RVR02 - Master of LT 500-1600 GRT

The Correct Answer is C. **Explanation for Option C (four to six seconds):** Option C is correct because the International Regulations for Preventing Collisions at Sea (COLREGs), Rule 32, defines a "prolonged blast" as a blast of from four to six seconds duration. This specific signal duration is mandated for use in restricted visibility (fog, mist, etc.) by power-driven vessels. * A power-driven vessel making way through the water in fog must sound a prolonged blast at intervals of not more than two minutes (Rule 35(a)). * A power-driven vessel underway but stopped and not making way must sound two prolonged blasts, with an interval of about two seconds between them, at intervals of not more than two minutes (Rule 35(b)). * In both cases, the "prolonged blast" itself must adhere to the 4 to 6 second duration defined in Rule 32. **Explanation for Incorrect Options:** * **A) about one second:** This duration is defined as a "short blast" (Rule 32) and is used primarily in maneuvering and warning signals (e.g., when vessels are in sight of one another, Rule 34), not as the primary fog signal for power-driven vessels. * **B) two to four seconds:** This range does not align with the regulatory definition of either a "short blast" (1 second) or a "prolonged blast" (4 to 6 seconds). * **D) eight to ten seconds:** This duration is too long and significantly exceeds the maximum time permitted for a prolonged blast (6 seconds).