Mike Kelly owns the Miss Jenna, a Russel Brothers Ville Class tugboat built for use by the RCN for duty on the East and West coasts of Canada. It has an approximate LOA of 40', beam 10' and interestingly virtually no keel. The drawings found, show a visible keel beginning about in the middle. A 4 1/2" width and about 1 3/4" depth, which becomes increasingly more moving aft.
http://www.russelbrothers.ca/xlisterville.html
Bill Froelich, Houston, Texas, built a fine 40" 1"=1' scale model seen here.
Bill and I have been in contact and have shared various ideas.