Here's how my surveyor says the hull numbering system works. It's a U.S. Coast Guard thing, so I don't know if it applied to all the C&C's that were built after 1972. The HIN is usually stamped into the stern somewhere above the water line. I have an older boat, so my hull number applies specifically to the model. It appears that linking the HIN to a particular model was abandoned after 1984. The stuff that follows was taken from my survey report.

"The hull identification number is required by the USCG to be displayed on all recreational boats built after October 31, 1972. The number consists of a combination of 12 letters and numbers identifying the builder, the model number, hull number, date of construction and model year.

Hull numbers used between October 31, 1972 and August 1, 1984 are asfollows:
1 2 3 = Builder's Code
4 5 = Model Number
6 7 8 = Hull Number
9 10 11 12 = Date of Manufacture ( 9 10 Month, 11 12 Year)
Or
9 = M
10 11 = Model Year
12 = Month of Manufacture; A = August B = September

Example: TSP90014M83B
TSP = Tillotson/Pearson
90 = Model 90
014 = Hull #14
M83B = Model Year, Construction began 1982, Code B = September

Hull Numbers used after August 1, 1984 are as follows:
1 2 3 = Builder's Code
4 5 6 7 8 = Hull Number
9 10 = Date of Certification or Manufacture (9 is Letter for Month;
A = January, 10 is Last Digit of Year)
11 12 = Model Year

Example: PYZ40012L586
PYZ = Present Yachts, Inc.
40012 = Hull Serial Number
L5 = December 1985 Date of Certification or Manufacture
86 = 1986 Model Year"