60’s crestliner?

Almost done rehabbing this 12’ boat, transom plate has the serial number as “ m 6712” I get the feeling this may be the year and hull size, anyone know? Need to advertise for sale soon, thanks.

From what I have seen and read (and I could be wrong), this indicates that it is a M-marine made in 1967 and in December.

I am not disagreeing with Jim.
On my 1962 AceCraft the serial number is 1862. The 18 is length and the 62 is the year built 1962.
I assume there are more AceCraft boats with the same serial number because the company would build more than one boat per month.
What year did the manufacturers have to start putting hull numbers on the outside of the transom? I think that is when serial numbers became actual production number like cars have.

According to the USCG:

"Prior to Nov. 1,1972 there were no requirements for a “HIN” to be assigned to recreational boats. Manufacturers used mostly serial numbers. The serial number assigned to the vessel by the manufacturer was unique to that manufacturer, but had no prescribed format beyond that specific manufacturer."

So prior to 11\1\72, individual manufacturers used their own system of numbering and the current system of numbering didn't come into effect until 8\1\84. Between '72 - '84 they were developing the system we have today.