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Hull Number Guidelines

What you should know about boat hull identification numbers.

A hull identification number or "HIN" validation is one of the most crucial elements of any boat title search or subsequent transaction. There are a host of reasons as to why any party with even a remote interest should know and understand what these unique identifiers are all about. This article will offer a detailed portrayal of assignment, formatting, and placement requirements for everything from ski-boats to mega-yachts. Unless otherwise noted, these rules will apply to recreational boats only and are subject to periodic revisions. You should check with the appropriate federal and state authorities before acting upon such data.

Historical Background -  Prior to November 1, 1972, there were no federal requirements for hull number assignments on any boat or watercraft regardless of type or size. Manufacturers used arbitrarily designated serial numbers which typically had no standardized format or meaning. There were in fact, many instances where an official Coast Guard documentation number was substituted as a builder's serial number. The Federal Boating Safety Act now requires that any vessel built for consumption within the United States must display a properly affixed manufacturer's hull number that conforms to federal standards. A primary reason for these uniform requirements pertains to the efficacy of recreational boat recalls. They are also used by the individual states for registration or titling purposes, by law enforcement to identify stolen boats, and by the Department of Homeland Security for national security purposes.

Manufacturer Identification Code -  Domestic boat manufacturers must obtain a unique identification code (MIC) in order to identify productions sold within the United States. The same applies to foreign manufacturers or importers. Vendors of kit boats which include plans and materials are also viewed as manufacturers. MIC designations are issued by the U.S. Coast Guard and consist of three characters. Although earlier codes may have contained a combination of numbers and letters, the practice of incorporating numbers is no longer applicable. Codes issued to previous builders no longer in business may be re-assigned to new applicants. Such coding will always appear as the first part of a hull identification number. Our website provides a detailed database of all manufacturer codes which contains historical and contact information.

Hull Number Assignments  -  Manufacturers with MIC designations may assign their own hull numbers so long as they are unique for each boat and comply with federal standards. If a foreign country has a hull identification number system which has been approved by the Coast Guard, it may be used by the importer. Hull numbers on homemade boats built from raw materials for personal use, boats owned and imported by individuals for personal use, and boats built prior to November 1, 1972 are issued on a case-by-case basis. In these situations, an assignment request must be submitted to the U.S. Coast Guard when vessel documentation is involved or the individual states as required by their particular regulations.

Hull Number Formatting -  Hull number formatting relates to way in which hull numbers must be structured. Such requirements have evolved in three different stages consisting of a Straight Year Format, a Model Year Format, and a New Format. The Straight Year format became effective on November 1, 1972 with the Model Year as an option. On August 1, 1984 the New Format became mandatory and displaced both of the earlier versions. All hull numbers contain the manufacturer's or a special assignment code, a serial number, the production month, and model or production year depending on the type of format. These typically culminate in a total length of 12 characters. Although certain exceptions may apply, such anomalies should be carefully investigated. Hull numbers may also be accompanied by additional characters which are usually separated by a dash or second line. However, these are not part of the actual hull number itself. Our website provides chart showing the various formats and an automated Hull Identification Number Verification page.

Hull Number Placements -  Hull identification numbers must consist of continuous characters at least one-quarter inch in height and uninterrupted by spaces, slashes, hyphens or other symbols. These 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 may not be attached to parts of the boat that are removable. On boats with transoms, the HIN should be displayed on the starboard outboard side of the transom within two inches of the top of the transom, gunwale, or hull/deck joint, whichever is lowest. Those without transoms or on boats where it would be impractical to use the transom, a HIN should be displayed on the starboard outboard 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. Catamarans and pontoon boats which have readily replaceable hulls, should display a HIN to the aft crossbeam within one foot of the starboard hull attachment. As of August 1, 1984 a secondary or hidden hull number must also be affixed in an unexposed location on the interior of the boat or beneath a fitting or item of hardware.

Inspection Requirements -  There are numerous circumstances where state or Coast Guard agencies may require a physical verification of the hull identification number. These commonly arise when documentation or registration applications are accompanied by questionable, incorrect, conflicting, outdated, or missing hull numbers. They may also occur in conjunction with enforcement activities such as boarding inspections, accidents, and various operational activities in general. A qualified marine surveyor will also verify the vessel's hull number as part of a transactional inspection. Hull number inspections are typically evidenced by stencil rubbings, photographs, affidavits, and other forms of certification.

Hull Number Corrections -  Boat hull identification numbers typically enter the pubic domain upon issuance a Manufacturer Statement of Origin (MSO) or a Builder's Certification. These are effectively a boat's first title document which designates the party for whom built along with various specifications. Once issued they may not be duplicated and any corrections must come in the form of a written statement from the manufacturer. If no longer in business, an affidavit along with supporting evidence from the current owner will usually suffice. In the event of a government issued hull number, the respective agency must rectify any errors or omissions. In contested situations, it may ultimately take a court ruling to settle any issues.

Thank you for considering these guidelines and we hope the information was helpful. Our publication is maintained as an open wiki forum where readers are encouraged to participate. Please share any thoughts you may have about this subject matter.

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