Question 52 ONC04 - Mate of LT 500-1600 GRT

The Correct Answer is D **Explanation for Option D (Correct Answer):** The signal consisting of four short blasts followed immediately by one long blast ($\cdot \cdot \cdot \cdot -$) is a specific maneuver signal defined in the operational procedures for vessels navigating in ice, particularly those used by the U.S. Coast Guard and other icebreaking operations. This signal explicitly means that the vessel sounding the signal (in this case, the icebreaker) has become **icebound or stopped involuntarily** in the ice and that all vessels being escorted or following must **stop immediately** to avoid collision or becoming trapped themselves. **Explanation for Incorrect Options:** **A) The vessel has its engines full astern, stay clear:** This is incorrect. While specific signals indicate astern movement, the signal four short and one long blast is dedicated specifically to the "icebound/stop" condition. The standard signal for "I am operating astern propulsion" is three short blasts ($\cdot \cdot \cdot$), though specialized operational signals may vary slightly. **B) The vessel is increasing the distance between vessels:** This is incorrect. Increasing distance (often referred to as "opening up") might be signaled by other means (often involving changes in course or speed signals), but not by the specific four short and one long blast signal, which mandates an immediate halt. **C) The vessel is increasing speed; watch for broken ice:** This is incorrect. Increasing speed would typically be signaled using the standard maneuvering signal for "I intend to overtake" or specific ice-operations signals for increasing speed (often five short blasts, or $5 \times \cdot$, signaling caution and increased speed/breaking effort), but not four short and one long.