The families of two fishermen, one of whom died after their boat capsized at Cromwell weir, on Monday visited the scene of the tragedy.
Mr Ian Steel, 57, of Pocklington, Yorkshire, was pulled from the River Trent by rescuers on Saturday but later died in hospital.
His best friend, Mr Neville Payne, 48, also of Pocklington, remains in hospital where he is being treated for hypothermia and the effects of swallowing polluted river water.
Collingham Angling Association, which controls angling on that stretch of river, has called for a barrier to be installed to prevent fishing boats getting too close to the weir.
British Waterways said it was reviewing safety at the weir, and would discuss the matter with the association and the fire service.
It said it would consider extra warning signs and other measures.
Mr Steel and Mr Payne were fishing for pike, which hunt in turbulent waters.
A key part of the investigation into what happened centres on how their collapsible boat, powered by a small outboard motor, came to be on the wrong side of a sign warning boaters not to go beyond a certain point.
The boat was sucked into the weir by strong underwater currents, and flipped over by the force of the water.
The men’s plight was seen at around 10am by lock-keeper Mr Sean Julian who called the emergency services.
Firefighters estimate the men had been in the water for up to 20 minutes when they arrived.
Specially trained swimmers pulled Mr Payne out within five minutes. He told them his friend was also in the river.
It took a further ten minutes to rescue Mr Steel by boat.
By that time his life vest and much of his clothing had been ripped off by the force of the water.
Station manager Mark Mortimore, of Nottinghamshire Fire and Rescue Service, said: “They were fishing below the weir and a tow-back current got hold of them and dragged them towards the weir.
“It has overturned the boat and they have gone into the water. It is a recycling weir, and the volume of water going over it makes it so powerful.”
He said the weir, which is used by firefighters for training exercises, was one of the most dangerous in the country.
Mr Steel’s son, Chris, 26, of Nottingham, said after visiting the scene on Monday: “They were passionate about their fishing and went often together.
“Dad was doing something he loved.
“They were not gung-ho or stupid. It caught them unaware and if you are not from the area and don’t have the experience of fishing here it can happen.”
He thanked Mr Julian whose promot action, he said, meant one of the men was survived.
Mr Ian Steel’s partner, Sandie Welsh, 57, said: “He was a very strong character.
“He knew his own mind and was very driven, optimistic and fun-loving. We were devastated when we heard. He will be sorely missed. He was a fantastic partner and father.”
Mr Payne’s wife Julia, with whom he has three children, said her husband had been fishing at Cromwell before, but Ian hadn’t.
“We thought what a nice, tranquil place it was. We could see what the draw was for them,” she said.
She said her husband had been told of his friend’s death.
“I am not sure he will go fishing again,” she said.
“He certainly won’t in a boat.”
The families backed calls for safety improvements at the weir.
Pc Richard Gettings, who is investigating the incident for the coroner, said: “Cromwell Weir is incredibly dangerous. Boaters should avoid it at all costs so a tragedy like this is never repeated.”