Question 19 OSV02 - Mate - Offshore Supply Vessels

The Correct Answer is A. **Why Option A is Correct:** Option A describes the classic situation where a risk of collision definitely exists, as defined by Rule 7 of the International Regulations for Preventing Collisions at Sea (COLREGs), which applies to both International and Inland waters (where applicable). * **Bearing is constant (or nearly constant):** A constant bearing means the line connecting your vessel and the other vessel is not changing relative to your vessel's heading. * **Range is decreasing:** The decreasing range means the vessels are getting closer together. The principle established by Rule 7(d)(i) is that **"Such risk shall be deemed to exist if the bearing of an approaching vessel does not appreciably change."** If the bearing is constant and the range is decreasing, the vessels are on a collision course (Constant Bearing, Decreasing Range – CBDR). The location of the vessel (starboard quarter) does not negate the collision risk; it simply means the vessel on the quarter would be the overtaken vessel, but a risk of collision still exists for both vessels if they maintain course and speed. **Why the Other Options are Incorrect:** * **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** While the bearing is constant (a potential indicator of collision risk), the **range is increasing**. If the range is increasing, the vessels are moving apart, and a risk of collision does not exist, though they must still be monitored. * **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** Since the **bearing is changing rapidly**, the other vessel is crossing ahead or astern of you, and it is moving relative to your vessel's position. This change in bearing indicates that the risk of collision is minimized or negated, despite the decreasing range. A rapid change means it is unlikely to be CBDR. * **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** Both the **range is increasing** (moving apart) and the **bearing is changing** (not CBDR). These factors clearly indicate that a risk of collision does not exist.