HIN and CIN Encoding Rules: Manufacturer Code, Model Year, and Serial Number

The Hull Identification Number

The Hull Identification Number (HIN) is the unique serial number assigned to every recreational craft. Required under the RCD in Europe and by the USCG in the United States, the HIN enables traceability from production through the entire service life of the vessel. ISO 10087 defines the format and encoding rules.

The 14-Character HIN Format

The standard HIN consists of exactly 14 characters divided into three groups:

Characters 1-3: Manufacturer Identification Code (MIC)

The MIC is a three-letter code assigned by the national authority in the country of manufacture. Each manufacturer receives a unique code that identifies them globally. For example:

• A US manufacturer might receive a code like "AQB"
• A UK manufacturer receives their code from the BMF
• A Chinese manufacturer receives their code from the CCS or relevant authority

The MIC must be registered with the international database maintained by the USCG, which serves as the de facto global registry.

Characters 4-8: Model Designation and Serial Number

These five characters are assigned by the manufacturer and typically encode:

• Model designation — abbreviated model name or code
• Sequential serial number — a unique number within the model series

Manufacturers are free to design this section as long as each combination is unique to a single vessel.

Characters 9-14: Date and Year of Manufacture

The final six characters encode the production date in a specific format:

• Character 9 — month of production (A=January through L=December)
• Characters 10-11 — year of certification or model year (two digits)
• Characters 12-14 — model year or production year (three digits, with the first being the last digit of the year and the next two being "YYY" format)

For example, a boat certified in August 2026 would encode the date section as H26 followed by the model year digits.

Example HIN Breakdown

Consider the HIN: AQBR4505H26026

• AQB — Manufacturer Identification Code
• R4505 — Model R450, serial number 5
• H — August (8th month)
• 26 — Year of certification 2026
• 026 — Model year 2026

This format ensures that no two vessels share the same HIN worldwide.

CIN vs HIN: Understanding the Difference

The Customer Identification Number (CIN) is a related but distinct concept:

• HIN — permanently affixed to the hull, required by law, follows ISO 10087 format
• CIN — an optional secondary number assigned by some manufacturers for internal tracking, warranty registration, or dealer identification

The CIN does not replace the HIN and has no standardized format. Some manufacturers use the CIN to track dealer assignments, production batch codes, or customer-specific configurations. The CIN may appear on documentation but not on the hull.

HIN Placement Requirements

The RCD and ISO 10087 require the HIN to be:

• Permanently affixed — engraved, molded, or otherwise rendered indelible
• Located on the starboard side of the transom — within 50 mm of the top and 50 mm of the starboard corner
• Visible — not obscured by fittings, paint, or other markings
• Duplicate — a secondary hidden HIN must be placed in an undisclosed location for anti-theft purposes

Common HIN Errors

Frequent mistakes that cause compliance failures include:

• Incorrect MIC codes not registered with the authority
• Date encoding that does not follow the A-L month convention
• Missing hidden duplicate HIN
• HINs painted over or obscured during finishing
• Multiple vessels sharing the same HIN due to serial number errors

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