For vessels, a “hull” basically means “the main body of a ship.”  This tends to include the bottom of the vessel, its sides, and even its deck.  However, typically, the definition of “hull” does not include fittings such as engines, the mast, and so forth.  Vessels have what’s called a “Hull Identification Number” (or “HIN”). This number is the identifying code for a specific vessel. Think of it as a vessel’s fingerprint. No other boat has the same HIN.  Consisting of 12 to 14 characters, a HIN displays who manufactured the vessel as well as when among other information.  The first three digits of a HIN are the “Manufacturer’s Identification Code.” This reveals who manufactured the vessel. Examples include “LWE” for “Lowe Boats,” “YAM” for “Yamaha Motor Corp. USA,” “CCB” for “Chris Craft Boats,” and so forth.  The following five digits are the serial number the manufacturer assigned to the hull. These can be both numbers and letters. However, as the letters “Q,” “O,” and “I” could potentially be mistaken for numbers, they are not used.  To the right of that (and fourth from the right) is a letter. This letter tells you the month when construction on the vessel began. Each letter corresponds to month: 12 for December, 11 for November, 3 for March, etc.  The next number (and third from the right) displays the last digit of the year when the vessel was built. For example, a vessel built in 2014 would have a “4.”  The last two numbers, (the ones furthest to the right) display the vessel’s model year.  The above format applies to vessels that have been manufactured since August 1st, 1984. All vessels must bear a HIN if they were manufactured or imported on or after the date of November 1st, 1972. Vessels manufactured or imported before that date are exempt.  Interested parties can search for vessels by HIN or Official Number through our site. This will provide information such as the vessel’s name, its flag, its service (endorsement), its length, breadth, depth, its tonnage, when it was documented with the USCG and when that documentation will expire as well as other information.  Use this link to conduct a HIN lookup.  Most often, the HIN is found on the starboard (right) side of a vessel’s transom on the upper right.  More specifically, according to 33 CFR 181.219:  “The primary hull identification number must be affixed - on boats with transoms, to the starboard outboard 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 use the transom, to the starboard side of the hull, aft, within one foot of the stern and within two inches of the top of the hull side, gunwale, or hull/deck joint, whichever is lowest.”  “On catamarans and pontoon boats which have readily replaceable hulls, to the aft crossbeam within one foot of the starboard hull attachment.”  “If the hull identification number would not be visible, because of rails, fittings, or other accessories, the number must be affixed as near as possible to the location specified (above).”  Furthermore, the duplication HIN has to be affixed on the boat’s interior as well. The HIN number has to be marked in characters that are at least ¼ of an inch high and, if they were to be removed, altered, or replaced, it would be obvious.  To quote again from 33 CFR 181.219:  “The duplicate hull identification number must be affixed in an unexposed location on the interior of the boat or beneath a fitting or item of hardware.”  “Each HIN must be carved, burned, stamped, embossed, molded, bonded, or otherwise permanently affixed to the boat so that alteration, removal, or replacement would be obvious. If the number is on a separate plate, the plate must be fastened in such a manner that its removal would normally cause some scarring of or damage to the surrounding hull area. A hull identification number must not be attached to the parts of the boat that are removable.”  “The characters of each hull identification number must be no less than ¼ of an inch high.”  If you have further questions about hulls or USCG vessel documentation, contact the Vessel Registrar Center at info@usvesselregistrar.us or (800) 535-8570 Monday-Friday, 8 AM to 4:30 PM.