Between 1972 and 1984:
The boat manufacturer must display two identical hull
identification numbers, no less than one-fourth of an inch high, on each boat hull. The primary HIN must be permanently affixed (so that it can be seen from outside the boat) to the starboard side of the transom within two inches of the top of the transom, gunwale, or hull/deck joint, whichever is lowest. On boats without transoms or on boats on which it would be impractical to the transom, the HIN must be affixed to the starboard outboard
side of the hull, aft within one foot of the stern and within two inches of the top of hull side, gunwale, or hull/deck joint, whichever is lowest. The starboard outboard
side of the hull aft is the preferred HIN location for many manufacturers. On catamarans and pontoon boats the HIN must be affixed on the aft crossbeam within one foot of the starboard hull attachment.
Boats manufactured or imported on or after August 1, 1984, also have a duplicate secondary HIN affixed somewhere on an unexposed location inside the boat or beneath a fitting or item of hardware
. The purpose is to help authorities identify your boat if a thief or vandals remove or damage the primary HIN on the transom. It is illegal for anyone (manufacturer, dealer, distributor, or owner) to alter or remove a HIN without the express written authorization of the Commandant, U.S. Coast Guard.
courtesy of boatsafe.com
Have you checked the history
of your boat? why was the HIN apparently removed? if it was done lawfully then the CG should have a record
of the request.