If a vessel is unable to show required lights, what should be displayed instead?

When a vessel is unable to display the required navigational lights, the proper protocol is to show an all-round white light. This practice is essential for safety on the water, as the all-round white light serves as a signal to other vessels that the boat is in a less than optimal state and unable to navigate under standard conditions. It effectively communicates to other boat operators that the vessel is not functioning normally, helping to prevent potential collisions or misunderstandings regarding its status.

The all-round white light is visible from all angles and indicates a need for caution. It signals to other boats that they should navigate carefully around the vessel. Using alternative signals, such as black shapes, red flags, or any kind of gray flag, does not provide the same level of clear communication regarding the vessel's operational status. Thus, displaying an all-round white light becomes the most effective and safe choice in these circumstances.