The Cook Strait ferry Arahura has been given the all clear to sail.

Yesterday an electronic fault caused problems with the ferry's propulsion shafts - and tug boats had to be used to help the vessel into its Wellington berth.

Engineers worked on the vessel overnight, and are confident the fault has been found, and fixed.

After testing, Maritime New Zealand has given the Arahura the all clear to sail.

A decision regarding her 6.30pm sailing will be made at 4.30pm.

If she does sail, it will be freight only as passengers have been booked on the Kaitaki which sails at 8.30pm.

Investigations called for

Fresh calls for a full investigation into Kiwirail, after a ferry fault left Interislander passengers trapped in Wellington Harbour.

New Zealand First's Winston Peters says the Government needs to step up.

"We've gone from crisis to crisis on the Cook Strait ferries but nobody in Parliament wants to take any responsibility."

Transport Minister Simon Bridges admits there have been a series of issues in recent times.

"I'd characterise it as some bad luck, and also the product of a relatively old fleet here. I'd feel confident that they have the plans and processes to make Interislander work for the long term."

KiwiRail's acting chief executive David Walsh says the Arahua will be out of action for some time, until a full investigation is done into what happened.

"Interislander are working very hard and they do a very good job generally of contacting people to advise them of disruptions. I'd expect we should have enough capacity in the other two vessels to make sure our passengers can get across the Cook Strait."