What type of vessels may use an all-round white light instead of separate masthead and stern lights?

The correct answer is that power-driven vessels less than 12 meters in length may use an all-round white light instead of the separate masthead and stern lights. This provision is designed for smaller vessels to simplify their lighting requirements and make them easier to operate.

For those vessels, using an all-round white light fulfills the navigational light requirements of the Collision Regulations while maintaining visibility to other vessels. It creates a distinct and recognizable signal to indicate the presence of the vessel on the water, especially important for safety during times of low visibility or night operations.

Other options do not fit the regulations as clearly. Vessels longer than a certain length typically must adhere to a more complex lighting configuration to ensure appropriate signaling for their size. Furthermore, fishing vessels and sailing vessels have specific requirements based on their activities, which do not generally permit the use of an all-round white light in the place of standard navigation lights designed for power-driven vessels.