Which statement is true regarding navigation lights?

The statement that the color of lights indicates the side of the vessel is accurate and is an important principle in maritime navigation. Navigation lights serve a critical purpose in helping boaters identify the direction and orientation of other vessels, especially during low visibility conditions, such as at night or in fog.

Specifically, a red light is displayed on the port (left) side of a vessel, while a green light is shown on the starboard (right) side. This color-coding is standardized internationally, allowing for consistent interpretation among different vessels. Thus, when a boater sees another vessel, they can quickly determine which way that vessel is headed based on the combination of colored lights it displays.

The other statements do not hold true in the context of navigation lights. They are not limited to only sailboats, as all types of vessels, including powered boats, require proper lighting. Furthermore, navigation lights are necessary at all times, regardless of the time of day. Additionally, their use is mandated not just in crowded waters but in all circumstances where there might be potential collisions, ensuring safety at all times on the water.