As a relatively new SOS member I just happened onto this GREAT thread! Wonderful to see how primary research developed into a handsome model. Well done!
The two lines drawings: I suspect that these tugs were side launched. I have an early 1900’s book by a Great Lakes marine surveyor named Curr comparing innovative shipbuilding practices employed on the Great Lakes with those on the River Clyde in Scotland. He makes the case that by side launching, construction of the vessel could be simplified by building it with the keel level. With the keel level, it would be easier to erect the frames perpendicular to it. This would of course require that the hull be lofted this way.
A lines drawing with the stations drawn perpendicular to the waterline shows the vessel’s underwater shape as she actually floats. Perhaps it was made for this purpose. Unlike most vessels, tugs require immense power with the vessel moving very slowly or even standing still. Flow to the propeller at the after end of the boat is all important. A lines drawing drawn this way might have made this characteristic easier to visualize.
The tug Edna G is moored at Two Harbors, MN 26 miles from where I live in Duluth, MN. She is steel hulled built in 1896. She looks like the classic East Coast tug, not the Great Lakes type. Her steam plant is intact. Most of the time she is closed to visitors but this encourages me to get onboard.
Roger
