Boats have been unable to get through some bridges, stranding passengers
Network Rail has been accused of failing to properly maintain and operate swing bridges on the Norfolk and Suffolk Broads.
The Broads Authority said problems at Trowse, Reedham, Somerleyton and Oulton Broad bridges have affected boat users.
It said Oulton Broad bridge has been on restricted access to vessels for 168 days, while Trowse has been closed completely for 100 days.
Network Rail said repairs had proved complex but were being addressed.
All of the bridges have been operating a near-normal service for trains.
Oulton Broad bridge was closed in December 2007 for 14 days, but complications have meant the work programme is continuing nine months later.
At Trowse, near Norwich, the bridge has suffered from failures in a computer system that is now obsolete, preventing it from opening to shipping.
Angie Leeper, waterways strategy officer for the Broads Authority, said: "We have quite a few problems over the years with all of the bridges and I think the problems have increased in severity and the length that the bridges are closed."
Tug Wilson, who operates the Southern Belle Broads cruises, said bridges failing to open has caused his company's reputation to be lowered.
"We've had massive problems this year being stuck either side of those bridges with a boatload of passengers we can't take back again" he said.
"Network Rail is holding the development of our business back no end and has also caused us a lot of bad publicity by not being able to pick passengers up when we're supposed to and take them back to the same place."
Chris Mitchell, spokesman for Network Rail, said he was aware the rail firm must keep the navigation clear for vessels but said the firm was conscious of not disrupting thousands of rail passengers.
"These are complicated ageing structures and we've got an ongoing programme to upgrade them and their reliability," he said.
"We've had some teething problems and we've been working hard to resolve them."
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