No Hull I.D. Number? No Title?
My advice is to take this boat back to ever you bought it from!!
ALL O'DAY boats built after the 1972 Model Year have Hull I.D. Numbers. The 30 was introduced for the 1977 model year and the 28 for the 1979 model year. The HIN will be molded into the outside of the transom and read like: XDYSxxxxM77A for the 30 or XDYNxxxxM79A for the 28.
ALL boats 14' and over require a Title in the USA, you will not be able to register or document the boat without a proper title and HIN.
This may very well be a stolen boat!
As to whether she is a 28 or a 30, here are a couple of pictures of the 2 boats. If you saw them hauled out, the 30 has a deeper forward entry (bow sits lower in water)
But first the official specs of each design.
O'DAY 30
O'Day 30 Specifications
L.O.A.
29'-11" (9.12M)
L. W. L.
25'-5" (7.74M)
Beam
10'-9" (3.28M)
Draft (keel)
4'-11" (1.50M)
Draft (centerboard up)
3'-6" (2.18M)
Draft (centerboard down)
7'-2"
Sail area
441.3 sq. ft. (41.0 sq. M)
Displacement (keel)
10,500 lbs. (4775K)
Displacement (centerboard)
11,000 lbs. (5000K)
Ballast (keel)
4200 lbs. (1909K)
Ballast (centerboard)
4700 lbs. (2136K)
Mast above water
44'-0" (13.42M)
O’DAY 28 Specs
LOA: 28’3”
LWL: 22’11”
Beam: 10’3”
Draft: 4’8” (deep-keel) 3’8” (shoal-keel)
Displacement: 7300# deep-keel 7700# shoal-keel
Ballast: 2550# deep-keel 2950# shoal-keel
Sail Area: 396.9 sqft
Masthead above DWL: 40’1