Question 17 OSV01 - Master/Chief Mate - Offshore Supply Vessels

The Correct Answer is B **Explanation for Option B (Sidelights and a stern light) being correct:** The lighting requirements for vessels being towed are governed by the **International Regulations for Preventing Collisions at Sea (COLREGs)**, specifically Rule 24 (Towing and Pushing) and Rule 36 (Signals to attract attention). However, the general running lights for a vessel under 50 meters in length being towed (and not obscured by the towing vessel) are specified by the rules pertaining to vessels underway. Since the vessel being towed is not underway by its own power and is not technically "making way," its lighting requirements revert to the minimum required for a vessel underway, which are those lights necessary to indicate its size and direction of travel (i.e., its position in the tow). * **Rule 24(a)(ii)** states that when the length of the tow (from the stern of the towing vessel to the after end of the tow) exceeds 200 meters, the vessel being towed shall exhibit sidelights and a stern light. * **Implied Requirement:** Even when the tow length is less than 200 meters, the vessel being towed (unless obscured) must show the lights appropriate to its length as a vessel underway, which includes sidelights and a stern light, to show its presence and heading to other traffic. Furthermore, a vessel being towed alongside is structurally part of the "composite unit" but must still display lights to delineate the full breadth and length of the combined tow. Showing sidelights (red/green) and a stern light (white) fulfills the requirement to indicate the vessel's presence and direction of travel to approaching vessels. --- **Explanation for why other options are incorrect:** * **A) One all-round white light:** This is the light displayed by a vessel at anchor or a vessel less than 7 meters in length whose speed does not exceed 7 knots, or certain fishing vessels/workboats only showing this during specific operations. It does not indicate the vessel's heading, which is necessary for a vessel being towed alongside. * **C) A masthead light, sidelights, and a stern light:** Displaying a masthead light (or two, depending on length) indicates that the vessel is self-propelled and underway (making way). A vessel being towed alongside is not making way under its own power, so displaying a masthead light would be misleading and indicate a different operational status than the actual one. * **D) Only the outboard sidelight and a stern light:** While the inward sidelight (the one facing the towing vessel) is often obscured or deemed redundant, the COLREGs do not prescribe only showing the outboard light in this specific rule application. The primary requirement is to show sidelights and a stern light, ensuring the presence and heading are clearly visible to all approaching vessels, especially those approaching from the side opposite the tug. Omitting the sidelight facing the towing vessel is often done in practice to prevent glare, but the mandated lights are the full set of navigation lights (sidelights and stern light). Option B represents the full regulatory requirement for navigation lights.