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 Class No. on the plate is the actual Mariner Class/Sail number for the O'Day Mariner.

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

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.

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

Key to Month of Model Year

It should be noted that in the first format boats actually have the month by number 01=Jan and then the last 2 digits of the year built. Also the four digits of the hull serial number are the Mariner Class sail number (O'Day preceded the sail number with an F which indicates a Mariner).
Example: XDYF26040373
Class Sail Number is 2604. Boat built in 03 (March) 1973.

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.

Mariner Styles:

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 a forward hatch. Approximately hull No. 1415 to approx. 2372
1972 - O'Day forward hatch removed, aluminum interior cabin mast support added and modified the cabin companionway. Approximately No. 2372 to 3771 when O'Day stopped building Mariners.
1980 - 1984 Rebel Industries Spindrift Design built hull No. 4000 to 4078
1986 - to present Stuart Marine Corp. has built hull No. 4079 to present. (No. 4193 built by late 2005)