Question 24 TV03 - Towing Vessels - Western Rivers

The Correct Answer is A **Explanation for A being correct:** The red sidelight on a vessel must show light over an arc of visibility from straight ahead (the bow) to $22.5^\circ$ abaft the beam on its respective side (port side for red). * **Inland and International Rules (COLREGs Rule 21(b))** define the arc of visibility for sidelights as $112.5^\circ$ (from $000^\circ$ to $112.5^\circ$ on the port side, and $000^\circ$ to $247.5^\circ$ on the starboard side, relative to the vessel's heading). * Diagram D023RR typically represents a vessel viewed from above, with segments labeled A, B, C, and D. Segment A covers the $112.5^\circ$ arc beginning directly ahead and extending aft to $22.5^\circ$ behind the beam (the port quarter). This precisely matches the required arc of visibility for the red (port) sidelight. **Explanation for why other options are incorrect:** * **B is incorrect:** Segment B usually represents the arc from $22.5^\circ$ abaft the beam extending to $67.5^\circ$ abaft the beam (the stern quarter). Lights covering this arc would be stern lights or possibly towing lights, not sidelights. * **C is incorrect:** Segment C typically represents the arc $67.5^\circ$ abaft the beam to straight astern, or often the full arc of the stern light ($135^\circ$ centered on the stern). The red sidelight does not shine directly astern. * **D is incorrect:** Segment D would usually represent the area forward of the vessel, possibly covering the arc of a masthead light or the arc of the green (starboard) sidelight (if the vessel is facing the opposite direction), but not the arc specific to the red sidelight as depicted in relation to the vessel's port side.