Spirit of Tasmania Ferry Investigates Navigational Issue

An investigation has been launched into a navigational issue that affected one of the Spirit of Tasmania ferries as it approached the Victorian coast last week.

Track maps show Spirit I was heading towards its destination at Geelong in the early hours of Thursday morning when it went off its standard route and made a U-turn close to Point Lonsdale.

"As the vessel was preparing to transit through Port Phillip Heads … the master identified an issue with the ship's navigation equipment," ferry owner TT-Line said in a statement.

"As a precaution, the vessel returned to open water to reset the system before proceeding."

The reset was successfully completed and the vessel arrived safely at the Port of Geelong, approximately 20 minutes behind schedule.

TT-Line's chief executive Chris Carbone said safety was its "number one priority".

"The company is fully investigating the occurrence and has commenced an independent review to better understand the circumstances," Mr Carbone said.

"A report was made to the Australian Maritime Safety Authority (AMSA), which is standard practice for incidents of this nature."

It is not yet known whether the navigational issue was related to a technical fault or a human error.

TT-Line said it elected to have a pilot on board the ship the following evening.

In a statement, AMSA said the incident was reported by the vessel's operator that day and that it was "working with TT-Line to establish what occurred and what corrective action is required".

The Spirit of Tasmania I and its sister ship Spirit II have been transporting passengers and cargo across Bass Strait since 2002.

They will make their final sailings from Devonport to Geelong on Thursday and Friday, respectively.

The ships will be replaced by two new ferries, Spirit IV and Spirit V, which will take their first passengers from October 31.

TT-Line is trying to sell the older ferries, but it remains unclear where they will be berthed until a buyer is found.