Joe Fossey notes, this is our current best guess as to how a Russel design became the "Ville" class...
Canada was at War and desperately needed all the strategic Wartime goods as soon as possible. Aircraft factories, Truck factories, Shipyards, Munitions factories and essential companion products were mandated by the government to be produced as quickly as possible.
As far as the "Villes" go, it is my submission that Harry H. Warkentin's trim little 40 foot workboat (see Bluefin) built c. 1937-38 was a ready to go product with no research and development required...It was just what the Navy was looking for in a small harbour tug and Russel Brothers had the plant facility to go into immediate production. It was the Navy Brass and procurement department who assigned the name "Ville" to this class.
I do recall hearing about an ex Navy inspector who volunteered that they were always happy to see Russel built boats coming down for their pre-acceptance tests because they were all well built and well tested.
The Russel Brothers official plan of the Ville is design number 250 and listed as a 40 foot Diesel Tug with a L.O.A. of 40 feet. This abbreviation (L.O.L.) relates to Length Over All. signed by Harry H. Warkentin who designed this hull circa 1938. It 's recorded that the first one sold was named Blue Fin and sold to the Ontario Government as a survey vessel. Of interest it had a straight vertical bow and I am quite sure it is still around today much modified over the years and last seen lying in a Goderich Marina.
The "Ville Class" name came of a necessity from WW II when Russel's built 38 of them for the Canadian Navy. At that time Navy Standard of hull length measurement along with Lloyds of London and Department of Transport was measured from the waterline perpendicular at the bow to the center of the rudder post. Thus the 37 feet 5 inch number vs. the shown 40 feet L.O.A. Another measurement is designated L.W.L. which means Loaded Waterline Length. I have this factory 40 ft. Diesel Tug or Ville Drawing if you need it.
As for the Upper Stem Cant Back from the Sheerline. The Ville was a Multiple Purpose Small Tug and would have on occasion been used as a "Shiphandling Vessel", now know as "Ship Assist" Vessel. When pushing against large vessels the angle back allowed it to have a better contact between the two surfaces v/s a sharp point that could possibly dig in and damage both vessels. Ship Assist design to this day provide this feature.
I have an official R.C.N. Lines Drawing of the H.M.C.S. Parksville, one of four Ville's shipped to the West Coast and active there for many years in CFB Esqimalt. Drawings like this are now scarce to non existent and much needed if any Transport Canada Inspection is required.
As to minor differences in Wheelhouse measurements. During standard production runs they could and did of necessity issue E.C.O's or Engineering Change Orders to change or modify slightly for Civilian customer needs.
Donal M. Baird, in his book "Under Tow: A History of Tugs and Towing" writes (page 95): " The first new tugs to come to the aid of the Navy, whose ship handling problems were becoming exacerbated by the presence of dozens of new warships, were the fifteen little, 40-foot, 150bhp, steel yard tugs of the Ville class (e.g. Otterville, Marysville, Merrickville and Beamsville). These were built in the tug specialist Russel Brothers shipyard, now in Owen Sound, Ontario, to work mainly at Halifax and Esquimalt. They arrived on the scene in 1943 and 1944 and were fine for handling corvettes, but too small to handle berthing of larger ships."