Talking of tugs, I am in London and lived against the Lea Navigation for most of my life and would see the tugs pulling 200ton barges often. They used shire horse too.
About ten years ago, I was on the Grand Union Canal and saw a Lea barge fitted with an outboard motor. I never imagined that an outboard could be powerful enough to shift a 200-ton load along a canal. Anybody seen anything similar?