What is an important visual characteristic of registration numbers on boats?

The requirement for registration numbers on boats to be easy to see ensures that they can be quickly identified by authorities and other boaters. This visibility is crucial for safety and legal compliance, as registration numbers help in tracking ownership and ensuring that vessels are properly registered. The numbers should stand out against the background of the boat's surface, making it effortless to read from a distance.

While brightly colored or reflective numbers can contribute to visibility, the primary aim is that they must be easy to see. Glow-in-the-dark features, while they may assist in low-light conditions, are not typically mandated and are less reliable than numbers that are simply conspicuous under normal lighting. Therefore, focusing on the ease of visibility encompasses various factors that ensure compliance and enhance safety on the water.