As I'm finishing up my first boat (Jolly Jay, renamed Sarah J) I have been looking closely at the number posted on fishing vessels that is usually located along the railing or on the wheelhouse (see picture). Most are 5-digit numbers, but some are 6. Does anyone know what these numbers are for? And does the number of digits reflect where the boat's home port is? They're not HIN numbers obviously, but I can't tell if it's a fishing permit # or a vessel #. I don't want to put a 6 digit # on my boat if it's supposed to be a 5 (kinda spoils the scale look).