Trevor and Sarah on NB AtLast returned from their recent cruise last weekend. It had been a good trip for them, but they'd had a nasty shock in Braunston Tunnel on their way out.
As they drove through the tunnel, they heard shouting. They couldn't hear the words. Soon, they saw a boat approaching. The shouting continued, and they stopped to see what was going on. There was no-one at the helm. The lone skipper had fallen off the moving boat, and was clinging on to the side, not daring to let go for fear of being sucked into the propellor. He was cold and wet, and very tired. Sarah took the helm of AtLast, and Trevor stepped onto the other boat.
Bear in mind here that there is barely room for two narrowboats to pass in a tunnel; the man could easily have been crushed, too. To cut a longish story short, despite the darkness of the tunnel, and his lack of familiarity with the boat, Trevor was finally able to bring it to a halt, haul the man aboard, and help him to continue on his way. He was exhausted, and possibly suffering from hypothermia, but was able to continue, with the intention of getting help when he got to the far end of the tunnel.
In the circumstances, it's very likely that Trevor and Sarah saved the man's life.
Talking with him, Trevor deduced that the man had "had an altercation" with the skipper of another boat, and a collision had occurred. He met up with that man at Braunston. He'd been "very cagey", but there was no doubt in Trevor's mind that he had been responsible for the man falling off the boat.
Boaters, beware of stroppy boaters, and avoid conflict!