Question 39 ONC04 - Mate of LT 500-1600 GRT

The Correct Answer is C 1. **Why option C ("four to six seconds") is correct:** The whistle signals used by vessels in restricted visibility (fog, etc.) are governed by Rule 35 of the International Regulations for Preventing Collisions at Sea (COLREGs), which applies to both International and Inland waters (as most Inland regulations mirror COLREGs for this topic). A "prolonged blast" is defined in Annex III, paragraph 1(b) of COLREGs as a blast of duration from **four to six seconds**. This is the standard duration for the prolonged blast used by a power-driven vessel when sounding signals in fog, whether making way or underway but stopped. 2. **Why each of the other options is incorrect:** * **A) about one second:** This duration defines a **short blast** (Annex III, paragraph 1(a) of COLREGs). A short blast is used for maneuvering signals (Rule 34) and specific fog signals (e.g., a vessel not under command, restricted in her ability to maneuver, or towing uses one prolonged followed by two short blasts). * **B) two to four seconds:** This duration falls outside the defined range for either a short blast (approx. 1 second) or a prolonged blast (4–6 seconds). * **D) eight to ten seconds:** This duration is too long for the defined prolonged blast (4–6 seconds) and does not correspond to any standard, defined whistle signal duration in COLREGs.