Ferry commuters, including those to Macau and China, are being advised to leave extra early this morning to avoid a demonstration by barge operators who plan to stage a slow-sail through the harbour. About 150 vessels - 100 lighters and 50 tugs - are expected to take part in the protest organised by the Public Cargo Working Areas Joint Committee. The group is protesting against the Government's plans to overhaul the operation of public cargo working areas. Additional Marine Police and Marine Department vessels will be deployed to help control the tugs and barges. The flotilla will muster near Green Island before heading through the harbour at about 8 am. It will pass Central, North Point and Lei Yue Mun before entering the eastern approaches where the vessels will turn round and make a return pass through to Western. The parade is expected to finish at about 10 am, but it could be another hour before services return to normal. 'We are advising people to leave home earlier than usual,' a Marine Department spokesman said. He said the department had tried to persuade the operators to delay their protest until 10 am, but they had not made any response. Operators are angry because the Government wants to put the nine wharves out to public tender among existing users, but barge associations believe it will force companies out of business. Yesterday, marine officials issued warning letters to all ferry operators and shipping companies advising them of the problem. Star Ferry general manager Frankie Yick Chi-ming said disruption was expected, but senior staff would be on standby to help keep delays to a minimum. 'We can't predict how badly services will be affected,' he said. 'It depends how fast and how large the fleet is. I hope it won't cause too much inconvenience, but it is being held during peak hours.' Hong Kong Ferry is also expecting delays, although it could not tell how badly its schedules will be disrupted. 'We will do our best to transport our passengers. And we hope our passengers understand if there are delays,' spokesman Jenny Seng said.