Final answer:
A vessel is required to display a special flashing light to indicate it is restricted in its ability to maneuver due to certain operations such as laying cables or underwater work. This light is yellow and flashes at a frequency of 50 to 70 times per minute to ensure high visibility to other vessels.
Step-by-step explanation:
A vessel is required to exhibit a special flashing light to indicate that it is engaged in certain operations that restrict its ability to maneuver, making it a 'vessel not under command' or 'restricted in its ability to maneuver' under international maritime rules. This may include vessels engaged in laying, servicing, or picking up a navigation mark, submarine cable, or pipeline; vessels engaged in dredging, surveying, or underwater operations; vessels engaged in replenishment or transferring persons, provisions, or cargo while underway; or vessels engaged in launching or recovery of aircraft. The special flashing light is yellow and flashes at regular intervals at a frequency of 50 to 70 flashes per minute. This is to ensure visibility and to alert other vessels of their restricted capacity, which typically takes precedence over ordinary navigation rules.
Additionally, vessels such as tugboats may display a flashing yellow light when towing alongside or pushing in a composite unit, as specified under local regulations. The use of such lights aims to enhance safety at sea by providing other seafarers information critical for avoiding collisions and navigating safely around vessels that are not fully maneuverable.