It joins MV George Bass, which will be used as a back-up.

James Grant was built in Queensland and left Brisbane last Friday at noon.

When The Mail spoke to Inter Island Ferries owner Frank Denvir on Monday afternoon, James Grant was three hours south of Eden and expected to berth at Stony Point at 10 o'clock that night.

"The ferry was supposed to come down a month ago but we've had bad weather," Mr Denvir said. "We've been waiting for a high [pressure system] and the weather finally improved last week."

The delay has upset plans by the state government to "launch" the new vessel, with Transport Minister Martin Pakula being forced to reschedule a trip to Western Port.

Mr Denvir did not know when the launch would be held but was expecting to hear from the government in coming days.

James Grant is slightly bigger than George Bass and can carry 110 passengers. It has state-of-the-art navigation and radio equipment, stereo audio and a television. It is 18 metres long on the water line, six metres wide and has an aluminium hull.

Two 500-horsepower Yanmar diesels push it to a cruising speed of 24 knots.

Its draught is just 90 centimetres, which is handy when berthing at Tankerton jetty on French Island, which is only two metres deep at low tide.

Inter Island Ferries has an enviable punctuality record with 99.7 per cent of trips departing and arriving on time, despite the sometimes rough conditions in Western Port.

The new ferry is named after the man who first mapped Western Port. In 1801, three years after George Bass "discovered" Western Port, Governor Philip Gidley King dispatched Lieutenant James Grant to make a detailed survey of Bass's discovery.