Question 15 OSV02 - Mate - Offshore Supply Vessels

The Correct Answer is A **Explanation for A (Neither vessel is the stand-on vessel.) being correct:** The scenario describes two vessels crossing in restricted visibility (fog) where they are **not in sight of one another**. This situation is governed primarily by Rule 19 (Conduct of Vessels in Restricted Visibility) of the International Regulations for Preventing Collisions at Sea (COLREGs), which applies internationally and to inland waters that adopt COLREGs. When vessels are not in sight, the concept of "crossing" defined by Rule 15, which dictates stand-on/give-way responsibilities, does not apply. Rule 19(d) addresses a vessel hearing a fog signal forward of her beam and determining that a risk of collision exists. This rule mandates specific precautionary actions (such as reducing speed, stopping engines, and navigating with extreme caution) but **does not assign stand-on or give-way roles.** All vessels must take action to avoid collision. Therefore, neither vessel is the designated stand-on vessel. **Why the other options are incorrect:** * **B) The vessel which hears the other vessel's fog signal first:** The order in which fog signals are heard is irrelevant to determining navigational roles. Rule 19 requires action regardless of which vessel detects the risk first. * **C) The vessel which has the other on her own starboard side:** The crossing rule (Rule 15), which defines the stand-on vessel as the one with the other vessel on its port side, only applies when the vessels are **in sight of one another**. In restricted visibility where vessels are not in sight, this rule does not apply. * **D) The vessel which has the other on her own port side:** This definition would typically describe the stand-on vessel under Rule 15 (if they were in sight). However, because they are in fog and not in sight, the crossing rules are suspended, and both vessels must take appropriate action under Rule 19.