Skip to main content
HomeHull ID Help



     The following information will help you determine the Hull Number (Mariner Class/Sail Number), the month and year your Mariner was built and when the different topsides styles were built.

     From 1963 when the first O'Day Mariner was built until November 1972 the boats had a metal plate attached to either the rear of the cockpit or on the centerboard trunk. The first, larger number is the total number of boats built by the O'Day Corporation, including all classes of boats. The Class No. on the plate is the actual Mariner Class/Sail number for the O'Day Mariner.

Early serial number / class number plate from a 1968 boat ... #1306.
This is the 18,695th boat built by O'Day and the 1,306th Mariner built.

The following Sail Numbers were built in approximately the following years:

Year Built   Sail Number (Class Number)
1963 1-92
1964 93-256
1965 257-437
1966 438-818
1967 819-1147
1968 1148-1414
1969 1415-1725
1970 1726-2053
1971 2054-2371
1972 2372-2560

     All boats manufactured or imported on or after November 1, 1972 must bear a Hull Identification Number (HIN). The HIN is a 12 character serial number that uniquely identifies your boat. The HIN has an important safety purpose. It enables manufacturers to clearly identify for boat owners the boats that are involved in a defect notification and recall campaign.

     A HIN is not the same as a State registration number, which may be required to be displayed on the bow of your boat. The HIN is a Federal requirement; your boat's registration number is a State requirement similar to the license plate on your car. The HIN, however, is required to be shown on the State title or certificate of registration.

The following two formats for the HIN were used until August 1, 1984.

Location of serial number (HIN) on a 1978 O'Day boat.

Key to Month of Model Year
AUG  A    FEB  G
SEP  B    MAR  H
OCT  C    APR  I
NOV  D    MAY  J
DEC  E    JUN  K
JAN  F    JUL  L

Example #1: XDYF26040373

     In this example XDY is the designation given to the O'Day company and F means it's a Mariner. 2604 is the sail number, the 0373 means the boat was built in March 1973.

Here is an actual molded in serial from a 1978 boat.
Code XDY (O'Day), F (Mariner), 3627 (Sail Number),  M (Spacer), 78 (Year) D (Nov. built)

Example #2: XDYF2547M72E

     In this example XDY is the designation given to the O'Day company and F means it's a Mariner. 2547 is the sail number, the M was used as a spacer and the 72E shows that the boat was built in December 1972.

Starting August 1, 1984 the letter designation for the month built next to the year built starts with A=Jan, B=Feb. etc.

     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.

Sample of a Stuart Marine HIN from Boat # 4200
Number is located in the upper right of the transom.

Mariner Style Chronology

1963 - O'Day fixed keelboats No. 1-92. Some of the initial centerboard boats were also built. We know of centerboard boat No. 20 still sailing @ Surf City YC.

1963 - 1968 - O'Day centerboard design with the open cabin and hatch forward to approx. Hull No. 1414.

1969 - O'Day 2 Plus 2 design that has sleeping for 4, self bailing cockpit, full cockpit to the transom, closed in cabin and an opening forward hatch. Approximately hull No. 1385 to approx. 2372

End of 1971 - O'Day forward hatch removed and replaced with a rounded cabintop, added aluminum interior cabin mast support  and modified the cabin companionway slides.

1973 -1979 - O'Day built sail numbers 2372 to 3771. Sail number 3771 was the last O'Day Mariner built.

1980 -1984 - Rebel Industries Spindrift Design built hull No. 4000 to 4078

1986 - Stuart Marine Corp. has built hull No. 4079 to No. 4213 built by late 2009