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Is it possible to find out the production year of my boat from its serial number?
Serial no. placement 
This question was posed in the pier talk in 2002. Since then, and also earlier, many have had the same question.
The serial number, or more precisely, the production number or hull number, shows that Coronet had several number series that were changed around 1970 and subsequently twice during the 1980s. The hulls were not manufactured together with the deck and superstructure, so it is the hull number that is relevant for verifying the age of the boat. The hull number was also the only serial number given on the Data sheet in the Owner's manual delivered together with the boat when new.
For the older Coronet models with GRPenforced plywood hulls we unfortunately do not have much information. An Explorer 22 from the 1960s may have a serial number 22a6357, but we do not know how to interpret the number.
You can find the hull number of your Coronet on the inside of the transom, either in the centre or on the port side of the transom above the engine shield. The number is embedded under the uppermost transparent layer of the topcoat and is not easily removed. Hence, even if the engine compartment has been repainted, the number is most probably left intact beneath the paint. If you are uncertain where to find the hull number, check with another owner of the same model. When you have found it, remember to add the hull number under Membership information.
In summary, there are four types of hull numbers:
In addition, there are different serial numbers for the Canadian boats from 19761977. For example, a 31 Aft Cabin has according to its owner the number 2CA3101511766. Unfortunately, we know very little about these numbers.
This is how you interpret your hull number:
6digit hull numbers (19651970):
1st, 2nd and 3rd digit: Serial number for the year of production
4th digit: Size code
5th digit: Model code
6th digit: The last figure in the year of production

7digit hull numbers (1971c. 1982):
1st, 2nd and 3rd digit: Serial number for the year of production
4th and 5th digit: Hull size in ft
6th digit: Model code
7th digit: The last figure in the year of production

8digit hull numbers (c. 19821985):
1st and 2nd digit: Production year
3rd and 4th digit: Hull size in ft
6th digit: Model code
7th digit: The last figure in the year of production

Deck and superstructure serial numbers
The hull number should not be confused with the serial number of the deck and superstructure. You may find the latter, e.g. on a 21 DC, under the deck on the port side about 50 cm from the transom. As noted above, the hulls were not fabricated together with the deck and superstructure, but in the absence of a hull number it is possible to obtain an approximate production year with this other serial number. The type and placement of the deck and superstructure number vary with the model.
Until about 1970 it consisted of five digits and one letter, e.g. there is one 21 DC from 1969 with the number 39D 048. Possibly the second digit may reveal an approximate production year, if there is no hull number available (in this particular case 9 for 1969).
Around 19701982 the deck and superstructure number consisted of seven digits and one letter, e.g. 2117 D 061 on a 21 DC from 1977. The fourth digit apparently matches the last figure in the year of production. Hence this serial number says something about the boat, although it is only the deck and superstructure number. The letter appears to be a code for the superstructure model.
Worth noting about serial numbers
The information given above is compiled from serial numbers for particular models reported by the members. Unfortunately the underlying data is not comprehensive enough for any solid conclusions. Apparently hulls intended for one particular model were sometimes fitted with a different superstructure; for example, a 21 ft hull fabricated to become a 21 Cabin could be fitted with a 21 DC superstructure instead.
Many members have submitted an "erroneous" model year in the membership information, an error in comparison with the hull number. It is possible that the boat was not sold the same year it was produced. It is also possible that earlier owners did not know but simply guessed the age of the boat, or had reason to conceal its true age.
The club encourages members who have not already done so to add serial numbers under Membership Information. The more serial numbers we have for each model, the more we can learn about their interpretation.