What's in a Number?

Hull Identification Numbers of Whitbys & Brewers

What is the Hull Identification Number (HIN)?

Whitby and Brewer boat owners often refer to their boats by the abbreviated 3-digit hull number (001-333) as a quick means of identifying which boat they own. For more detail and a fuller understanding of the origin of a boat, the full Hull Identification Number (HIN) is a 12- or 13-digit number which imparts information about the builder, length of vessel, hull number, and date built.

Beginning November 1, 1972, the HIN became required for all boats built in or imported to the United States. Transport Canada followed suit by requiring the HIN on all Canadian vessels beginning in 1981. Prior to 1981, Canadian builders often assigned an HIN if the boat was to be imported into the USA.

Each part of the HIN imparts specific information in a relatively simple way. In general, the first three characters are an MIC (Manufacturer Identification Code) assigned by the US Coast Guard to the manufacturer. The MIC for Whitby Boat Works is usually “ZWB,” but some of the earliest Whitby 42's used “WBW,” and the MIC for Fort Myers Yacht & Shipbuilding is “FMW.” The next five characters of the HIN are the hull serial number, and in the case of Whitbys and Brewers this begins with two digits to show length of the boat (in feet) followed by the three-digit hull number. The last four characters indicate the date the boat was built. For example:

HIN:  ZWB420620675 indicates Whitby Boat Works, 42 foot, Hull #62, hull laid in June 1975

 

HIN:  FMW422061280 indicates Fort Myers Yacht & Shipbuilding, 42 foot, Hull #206, hull laid in Dec. 1980

However, confusion can occur as there are several types of format for the HIN. Since 1972, there have been four different official HIN versions developed by the United States Coast Guard. From November 1, 1972 to August 1984 both the “Straight Year Format” and the “Model Year Format” were official USCG formats, and from August 1984 to the present the “New Format” and “New Format with Country” have been used. However, fairly often boat builders ignored the USCG rules and developed their own versions, e.g. Fort Myers Yacht & Shipbuilding's use of a different version of the HIN for some of their boats built in 1984-1987.

 

Interpreting Various Formats of the HIN

Straight Year Format

The “Straight Year Format” was in use from November 1, 1972 until August 1984. It consisted of 12 characters: 3 for manufacturer, 5 for serial number, and 4 for the date. Note that actual HINs do not make use of any spaces between characters. Spaces have been added in the following examples only for clarity.

Breakdown of HIN: ABC 12345 1273
ABC The first three characters are an MIC (Manufacturer Identification Code) assigned by the Coast Guard to the manufacturer. The MIC for Whitby Boat Works is usually “ZWB,” but many of their earliest Whitby 42's used “WBW.” The MIC for Fort Myers Yacht & Shipbuilding is “FMW.”
12345 The next five characters are assigned by the manufacturer as the serial number of the boat. In the case of Whitbys and Brewers the first two digits show the length of the boat (in feet) followed by the three-digit hull number.
1273 The last four digits indicate the month and year that the hull was laid, in this example December of 1973.

Examples of Straight Year Format HIN

ZWB420620675    Whitby Boat Works, Whitby 42, Hull #62, hull laid in June 1975

 

FMW422061280    Fort Myers, Whitby 42, Hull #206, hull laid in December 1980


Model Year Format

The “Model Year Format” was in use from November 1, 1972 until August 1984. This format was extremely rare for Whitbys and Brewers, but some cases do exist. This format consisted of 12 characters: 3 for manufacturer, 5 for serial number, 1 was always “M,” 2 for the model year, and 1 for the production date.

Breakdown of HIN: ABC 12345 M 74 E
ABC MIC - Same as the Straight Year Format. 
12345 Serial number - Same as the Straight Year Format.
M The next character was always an “M” to show this is Model Year Format
74 The next two characters show the model year of the boat and not necessarily the actual year of production. In the same way that cars produced at the end of a year are actually the next year's model, boats manufactured from January to July were assigned that year's model, but those manufactured in August to December are assigned the following year as the model year. So “74” would be assigned to any boats manufactured from August 1973 until July 1974.
E The last character was a letter (A-L) to indicate the month that the boat was produced according to the following key:
A - August
B - September
C - October
D - November
E - December
F - January
G - February
H - March
I - April
J - May
K - June
L - July

 

Example of Model Year Format HIN

FMW42243M84A    Fort Myers, 42 foot boat (Brewer 12.8 in this case), Hull #243, model year 1984, built August 1983


New Format

The “New Format” has been in use from August 1984 until the present. This format consists of 12 characters: 3 for manufacturer, 5 for serial number, 1 for the month of build, 1 for the year of build, and 2 for the model year.

Breakdown of HIN: ABC  12345  L  3  84
ABC MIC - Same as the Straight Year Format. 
12345 Serial number - Same as the Straight Year Format.
L The next character indicates the month in which the boat was built according to the following key:
A - January
B - February
C - March
D - April
E - May
F - June
G - July
H - August
I - September
J - October
K - November
L - December
3 The next character shows the year in which the boat was built. This character is either the last digit of the model year (for boats built in January through July) or the last digit of the year prior to the model year (for boats built in August through December). In this example, since the model year is 1984, the “3” indicates the boat was built in 1983.
84 The next two characters show the model year of the boat and not necessarily the actual year of production. In the same way that cars produced at the end of a year are actually the next year's model, boats manufactured from January to July were assigned that year's model, but those manufactured in August to December are assigned the following year as the model year. So “84” would be assigned to any boats manufactured from August 1983 until July 1984.

 

Example of New Format HIN

FMW44282K788    Fort Myers, Brewer 44, Hull #282, built November 1987, model year 1988

New Format with Country

The “New Format with Country” has been in use from August 1984 until the present. As far as the author is aware, no Whitby or Brewers have used this HIN format. This format consists of 15 characters: 2 for country, followed by “-”, 3 for manufacturer, 5 for serial number, 1 for the month of build, 1 for the year of build, and 2 for the model year.

 

Actual 15-digit HIN without added spaces:  CA-ABC12345L384
Breakdown of HIN: CA  -  ABC  12345  L  3  84
CA The first two characters are the 2-digit abbreviation of the country of the manufacturer. In this example, the country is Canada.
- The third character is always a “-” to separate the country from the MIC. This dash counts as a digit in the HIN.
ABC MIC - same as the New Format
12345 Serial number - same as the New Format
L Month of build - same as the New Format
3 Year of build - same as the New Format
84 Model year - same as the New Format

 

Unknown Formats from Fort Myers Yacht and Shipbuilding

From 1984 to 1987, Fort Myers Yacht & Shipbuilding adopted its own 13-digit format HIN for some of the Brewer 12.8's that it built. The code to these 13 characters of this unknown format is inconclusive as of this writing, but appears to be: 3 for manufacturer, 5 for serial number, 1 for the month of build, 2 for the day of build, and 2 for the year of build (or perhaps it is model year).

Breakdown of HIN: ABC  12345  L  21  84
ABC MIC - Same as the Straight Year Format.
12345 Serial number - Same as the Straight Year Format.
L The next character indicates the month in which the boat was built, and it is assumed that it follows this key:
A - January
B - February
C - March
D - April
E - May
F - June
G - July
H - August
I - September
J - October
K - November
L - December
21 The next two characters appear to indicate the day of the month in which the hull was laid. In this case December 21st.
84 The last two characters appear to indicate the year of production.

 

Example of Unknown 13-Digit Format HIN from Fort Myers

FMW42269K1387    Fort Myers, 42 foot boat (Brewer 12.8), Hull #269, hull laid November 13, 1987

Fort Myers seems to have used a combination of 12- and 13-digit HINs during this period from 1984-1987. Most of the 12-digit HINs seem to be in the New Format designated by the USCG, but others appear to be modified from this 13-digit version described above, where the last 4 characters appear to be month, day and year of production, where the day is a single digit. In the following example, the HIN is clearly not following the New Format because a 1985 model year would not be produced in 1982. So it is assumed that the “F285” simply describes the date of production.

Example of Unknown 12-Digit Format HIN from Fort Myers

FMW42255F285    Fort Myers, 42 foot boat (Brewer 12.8), Hull #255, hull laid June 2, 1985

If any reader has further conclusive evidence to clarify the codes of these 12- and 13-digit HINs from Fort Myers, please contact the author at This email address is being protected from spambots. You need JavaScript enabled to view it. so this article can be amended.