The last four numbers are the month and year of manufacture. Generally the first few numbers and letters denote the name of the manufacturer.
The caveat is that on older boats these rules of thumb may not hold true.
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HIN format:
1st 3 letters — manufacturer (GND == Grand Banks)
Letter & next 4 digits — model hull # / serial #
Letter & digit - month & year of production
Last 2 digits — model year