What type of light can be used by power-driven vessels less than 39.4 feet in length as a combined lighting solution?

Power-driven vessels that are less than 39.4 feet in length can use a combined lighting solution consisting of an all-round white light. This lighting configuration is designed to be practical and effective for smaller vessels operating during nighttime or periods of reduced visibility, providing both an indication of the vessel's presence and direction.

An all-round white light is beneficial because it can function as a masthead light and a stern light, fulfilling the requirements for both forward and rear visibility in one unit. This combination simplifies the lighting requirements for smaller vessels, making it easier for operators to comply with safety regulations without the need for multiple distinct lights.

In contrast, while a masthead light serves an important function for larger vessels by illuminating the forward direction, a stern light specifically indicates the vessel's rear, which may not be as necessary for smaller boats that can effectively be seen with the all-round white light. Similarly, red navigation lights are primarily used to show a vessel's position and are not suitable as a combined solution for the required lighting arrangement.