The Old Town canoe with serial number 11915 is a 16 foot long, CS grade, XX model with red Western cedar planking, closed spruce gunwales, ash decks, ash trim, spruce outside finish rails, a keel, and outside stems. It was built between September, 1909 and February, 1910. The original exterior paint color was dark green. It was shipped on March 3rd, 1910 to Seattle, Washington. A scan of this build record can be found by following the link at the attached thumbnail image 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 join or renew your membership to the WCHA so that services like this can continue. See
http://www.wcha.org/wcha/ to learn more about the WCHA and
http://www.wcha.org/join.html to join.
I saw pictures of this canoe on eBay at
http://cgi.ebay.com/_W0QQitemZ170056657100 and it may have had some extensive repairs at some point. It currently appears to have open gunwales and long decks like an Otca model. The Carleton model with this serial number had sponsons and no outside stems so that doesn't seem like a better match.
It is also possible that you could have another number or manufacturer if this description doesn't match your canoe. Feel free to reply here if you have any other questions.
Benson