I am very sorry you got this rubbish wrapped around your propeller. I do hope it didn’t take long to remove. I am writing to ask you to consider the possibility that the next time this happens instead of just dumping it on the towpath, you take it away with you and dispose of it properly. At the end of the day this is not the proper place to dispose of it however angry you are that it curtailed your journey. You may have ben stressed that you had to waste time removing it but think about the environment and the wild life, and the general pleasant surrounding, which I strive to keep nice on my way around the canals. It doesn’t take much to place this litter in a carrier bag and deposit it on your roof until you come to a proper disposal point. There was one less than two miles away.
Sorry to hear your brain operation went so badly what goes around comes around.