What does it indicate if a vessel does not display a masthead light?

When a vessel does not display a masthead light, it typically indicates that the vessel is a sailing vessel that is under sail rather than under engine power. In maritime navigation, the masthead light is an important indicator used by other vessels to determine the status of a boat. For sailing vessels, when they are sailing, they often do not need to display this specific light, as their operation is governed by different lighting requirements than those for motorized vessels.

In contrast, when a vessel is at anchor or not in use, it usually would display appropriate lights to indicate its status. Therefore, the absence of a masthead light signals to others that the vessel is primarily utilizing its sails for navigation, distinguishing it from motorized vessels that are required to show a masthead light when underway under engine power.