What is the minimum height for vessel registration?

The minimum height for vessel registration numbers is set at 3 inches. This requirement ensures that the numbers are clearly visible and easy to read, which is critical for identification purposes on the water. Proper registration numbers help authorities identify vessels quickly, enhance safety, and assist in recovering stolen boats. By ensuring that registration numbers are appropriately sized, it minimizes confusion and promotes compliance with maritime regulations.

Other options specify heights that do not meet regulatory standards, which could lead to difficulties in identification and enforcement on the water. Hence, the correct answer of 3 inches reflects the established guidelines for clarity and visibility in vessel identification.