Question 7 OSV01 - Master/Chief Mate - Offshore Supply Vessels

The Correct Answer is C **Why option C ("You may sound at least five short and rapid blasts on the whistle") is correct:** This scenario involves a situation where a vessel (the obligated vessel in the narrow channel) is in doubt as to the intentions of the crossing vessel. International Rule 9 (Narrow Channels) primarily governs movement within the channel, but the critical action required here is defined by Rule 34(d) (Maneuvering and Warning Signals) concerning uncertainty. Rule 34(d) of the International Regulations for Preventing Collisions at Sea (COLREGs) states: "When vessels in sight of one another, a vessel is in doubt whether sufficient action is being taken by the other vessel to avert collision, she **shall** indicate such doubt by sounding at least five short and rapid blasts on the whistle." The vessel in the narrow channel is constrained by the channel, and any doubt about the crossing vessel's actions requires the danger signal (five or more short blasts). **Why the other options are incorrect:** * **A) You must sound one prolonged and two short blasts:** This signal (one prolonged and two short blasts) is the required signal under Rule 35(c) (Sound Signals in Restricted Visibility) for a power-driven vessel that is **not** under command, restricted in her ability to maneuver, constrained by her draught, sailing, fishing, or towing when making way through the water in restricted visibility. It is not the signal for doubt in a crossing situation when in sight of one another. * **B) You should sound one short blast to indicate that you are holding course and speed:** A single short blast (according to Rule 34(a)(i)) means "I am altering my course to starboard." It is a maneuver signal, not a signal of intent to maintain course or speed, and using it incorrectly could mislead the other vessel. Furthermore, the question asks what to do when you are in *doubt*, which requires the danger signal, not a maneuvering signal. * **D) You are required to back down:** While backing down (reversing engines) might be necessary as a collision avoidance maneuver (Rule 17 and Rule 8), it is an action taken to avoid collision, not a required warning signal under Rule 9 or Rule 34 when merely experiencing doubt. The primary requirement when in doubt is to signal that doubt using the whistle (Option C).