Welcome, the Old Town canoe with serial number 181944 is a 15 foot long Lightweight model with a keel. It was built between November and December, 1968. The original exterior paint color was dark green. It shipped to Concord, Massachusetts on March 24th, 1969. A scan showing this build record can be found 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 donate, join or renew your membership to the WCHA so that services like this can continue. See https://www.woodencanoe.org/about to learn more about the WCHA and https://www.woodencanoe.org/shop to donate or join.
It is possible that you could have another number or manufacturer if this description doesn't match your canoe. Modern hull identification numbers will commonly have a date at the end but this is not true for older serial numbers like this. Feel free to reply here if you have any other questions.