Dilwyn Jones, owner of Sabrina boat tours, says he has caught young people throwing stones and rocks at the boat while it is hosting tours along the River Severn and has warned the perpetrators will be reported to police.
On Wednesday, a group of young people were caught throwing large stones at the boat twice during the day and Dilwyn says he took pictures and reported it to the police on both occasions.
He said: "We were really busy today with children and families on the boat. If one of those stones hit someone, it would do serious damage.
"I rang the police on the first occasion today and nothing happened. So I rang them the second time and it was registered as a priority but I didn't hear anything else.
"The side of the boat has been dented but the stone that hit the top, hit a piece of metal that went down the middle. It's lucky they didn't hit anyone.
"All summer we have had children jumping off the bridges in front of the boat and it makes us nervous – that's 30 tonnes of boat and a propeller.
"It does not make it safe. People need to be aware of this.
"One way or another these circles of people need to realise that actually they could hit someone or kill someone – the sort of stone they were throwing was not small."
Dilwyn said they have been experiencing this nuisance all summer holidays, and it has started again now its half-term.
"I get it's difficult at the moment but this is just mindless," he said.
"We got pictures of some of the kids and we will take pictures every time.
"We've had it all summer, 14, 15, 16 year-olds jumping in front of the boat, throwing stones.
"Always in the holidays. If you see it, report it. The more people report it the better."
People can call police on 101.