Drunken pranksters untied a houseboat from its moorings leading in a "terrifying" incident where the vessel crashed into the weir barrier at Jesus Green lock.
Amanda Gawthrope's boat, Zomeland, was untied from its moorings at Jubilee Gardens on Chesterton Road, Cambridge, during the night.
When she awoke the next day she discovered to her horror the boat had drifted into the weir barrier.
The prank comes after years of campaigning for more secure moorings by boaters.
The 47-year-old said: "Someone had deliberately let my boat off to see if it would go over the weir. I think it's just a drunken prank. It has happened to other boaters.
"If it had been a windy night, I would not have been able to get off there on my own. I would have been stuck there. It's terrifying with the weir churning away."
Currently, boat ropes are typically tied on to pins wedged in the riverbank, which can be dislodged by heavy weather, water movement or vandals.
Camboaters have been campaigning for mooring rings, fixed into the bank with concrete, for people to chain their boats to.
Few exist in the city, according to Camboaters, but a trial was agreed for Jesus Green by the city council in January 2009.Read more at http://www.cambridge-news.co.uk/Home/Call-for-new-moorings-after-late-night-houseboat-terror.htm