Iconic Manly ferries to return to Sydney Harbour

More of Sydney's iconic Freshwater-class ferries will be cutting their way to Circular Quay after new, foreign-built vessels that were bought to replace the older models were plagued with problems.

New figures revealed by the incoming NSW government show a stark increase in reliability issues, with Sydney Ferries recording seven incidents a month over the past year.

Transport Minister Jo Haylen pledged to return the ageing Freshwater vessels to service as quickly as possible and build future fleets in Australia to solve the system's reliability woes.

"These overseas-built ferries have caused significant incidents and passengers have been subjected to delays and cancellations," she told reporters on Tuesday. 

"That is a long way away from a reliable ferry service that we need on our harbour and on our rivers."

Over the same time period, Emerald-class ferries reported 52 incidents compared with seven on the Australian-built Freshwaters.

Additionally, the new River-class ferries are similarly beset by a defect list seemingly longer than the Parramatta River.

The introduction of the Indonesian-built catamarans was repeatedly delayed after they were found to contain asbestos, could not be used at night due to glare from the windscreens, were too high to fit under some bridges and had problems with their engines and gearboxes.

"The vessels that are most reliable on the current ferry service are the ones that were built here," Ms Haylen said.

"We will build the future ferries that we need here so that passengers in New South Wales can have a reliable ferry service."

The issues with the Emerald ferries are being dealt with and the fleet will continue to service the Manly route alongside the Freshwaters.

Of the four Freshwater ferries, only the Queenscliff and the Freshwater are in service after the Collaroy and Narrabeen were retired.

The previous coalition government planned to retire all the 40-year-old ferries over concerns about maintenance costs but wound back plans to scrap the entire fleet amid community backlash.

Meanwhile, Ms Haylen says blow-outs on the metro line linking Sydney's CBD to Parramatta are "shocking", vowing to be more transparent about project costs than her predecessors.

The under-construction Metro West project, due to open in 2030, is now expected to exceed $25 billion, after initial estimates projected a maximum cost of $18 billion.

The transport minister would not speculate about changes to the project, but acknowledged the challenges it faces as other states' mega-projects exacerbate an already tight labour market.