Connecticut Safe Boating Practice Test

The indication that a vessel is under sail is represented by the absence of navigation lights, specifically when the vessel is operating without an engine. When a sailboat is moving solely due to the wind, it does not display powered vessel lights. Instead, it relies on natural sunlight or moonlight for visibility. This means that if a vessel is under sail, it may not show its navigation lights at all, particularly during the day when it's already adequately illuminated by sunlight.

Sailboats typically exhibit specific lighting configurations only when they are under power or when they interact with other vessels at night. Learning this concept is crucial for safe navigation and understanding the implications of vessel operation modes, particularly regarding right-of-way rules and safe passage in shared waterways.

The other light types listed serve different purposes, such as indicating the direction of travel or vessel size, and their presence is not applicable when a vessel is solely under sail.