Welcome and congratulations, the Old Town with serial number 151920 is a 12 foot long, AA (or top) grade Sportboat with white Maine cedar planking, open mahogany gunwales, half ribs, and a keel, bilge keels, a bang plate, rowlocks, rub rails, and a painter ring. It was built between November, 1948 and January, 1949. The original exterior paint color was dark green. It shipped on January 21st, 1949 to Columbus, Ohio. A scan of this build record can be found by following the link at the thumbnail image attached below.
This scan and several hundred thousand more were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others. A description of the project to preserve these records is available at
http://www.wcha.org/catalogs/old-town/records/ if you want more details. I hope that you will contribute, join or renew your membership to the WCHA so that services like this can continue. See
http://www.wcha.org/about-wcha to learn more about the WCHA and
http://www.wcha.org/store/membership to join.
It is also possible that you could have another number or manufacturer if this description doesn't match your boat. The Sportboat model was listed in the catalogs from 1941 to 1971. The 1946 catalog page at
http://www.wcha.org/forums/index.php?attachments/34734/ has some more details. Feel free to reply here if you have any other questions.
Benson