My worst experience was going out of Brum on the Grand Union. I'd just been thinking how easy Brum had been when.....
Up on a really high bridge I saw some teen boys. As usual I smiled and waved - as close as I could get to engaging them. One of them said "oh look, she's waving".
Next moment, one of them who was positioned perfectly lifted a small tree / large branch over the parapet, and smiling at me aimed perfectly for the boat. It made contact with a loud thump about 3 feet from me. If it had hit me I'd have been badly injured, but my tough little Springer didn't even get a dent!
As I was single handed, and as the kids could have out run the boat, I just carried on as if nothing had happened - didn't give them the satisfaction of any reaction at all.
Once I was half a mile away, and out of sight of the bridge I phoned 999. They sent someone straight away, but as there was no actual damage done to me or the boat, I didn't hear anything.
The incident scared me witless, and I didn't stop until I was at Copt Heath Wharf. That night, every time I heard a sound I was wide awake.
Me and my little boat have done about half the system with friends / family / single handing, but I have not felt that frightened before or since.