Traditionally documnetation numbers would be permanently graven into a main timber of a boat, or burned in welding bead into steel plate, and so on.
What you want to do is make it obvious that a set of permanent numbers has been made a part of the hull, in a way that they cannot be easily removed or covered.
As Herb mentions, epoxy over black vinyl letters is common on plastic boats these days. That apparently satisfies the USCG criteria, although some of us would say that could "easily" be removed and replaced by anyone with a grinder.
As a backup, many folks would add the numbers in marker or crayon in some obscure location, i.e. on the bottom of the fuel tank or inside the transom above the rudder tube, so that a casual glance would never find them but they were readily found by someone who had been told where to look.
"Arabic numerals " That really bothers me. I don't read or speak Arabic, and whenever someone asks that I do, I remind them that I'm entitled to a translator. I do English, Binary, Hexadecimal and Roman numerals. I don't do Arabic unless I'm in Arabia. (VBG)
Last edited by hellosailor; 04-19-2009 at 06:46 PM.