Tugboat? Pipeline? Why there's no quick fuel fix for the Nuyina

The Nuyina has to make a 674-kilometre detour to refuel in Burnie. (AAD)

When the Australian government decided to spend $528 million on a state-of-the-art icebreaker, it was envisaged the ship would be able to refuel in its home port of Hobart.

But in 2023, the harbourmaster rejected an application for the RSV Nuyina to travel under the Tasman Bridge to reach city's marine fuel depot.

Since then, the Nuyina has had to sail to Burnie in Tasmania's north-west to fill up its tanks before heading south to Antarctica.

The 674-kilometre detour has added almost $900,000 to the ship's annual fuel bill.

That's despite the Tasmanian government previously promising to find one by next month as part of an agreement with the federal government.

The Nuyina's home port is Hobart, but it can't access the city's marine fuel depot 4 kilometres away. (Richard Jupe/Australian Antarctic Division)

That's small enough to go between the central pylons of the Tasman Bridge, which are 73 metres apart.

The ship also has plenty of head room to get under the bridge.

Ever since 1975, when a bulk carrier crashed into the pylons, ships of a certain size have needed approval to ensure they can safely pass under the bridge.

But when the harbourmaster assessed the Nuyina in 2023, he decided the risk would not be worth it, even with the ship's in-built redundancies.

A total of 109 computer simulations were conducted to examine how the Nuyina would perform if it were to go under the bridge.

The RSV Nuyina "hit" Hobart's Tasman Bridge four times during computer simulations. It's why the ship now has to make a long and costly detour to refuel.

The virtual ship ended up crashing into the pylons on four occasions.

It would have hit them a further 10 times if the simulation wasn't stopped mid-journey.

And it came dangerously close to the bridge on almost 50 per cent of the remaining computer-based assessments.

The Nuyina's relative lack of directional stability was linked to its rounded hull and its relatively large surface area, which can be heavily affected by wind.

It's not uncommon to see tugboats shepherding larger approved vessels through the navigational span of the bridge.

But when the harbourmaster assessed the Nuyina in 2023, he found this was not a viable option.

"Exposing a tug to the side of vessel where the safe passing distance was diminishing would not only have an expectation of push at all costs but … very quickly escalate to both dire and fatal consequences if exercised in reality," his report stated.

The marine fuel depot at Selfs Point is just 4 kilometr