Icebreaker construction requires laser precision

An artist’s impression of the Nuyina beside the Aurora Australis in Hobart.
An artist’s impression of the Nuyina beside the Aurora Australis in Hobart. (Photo: AAD/Serco)
An aerial view of the Nuyina in the dry dock.An aerial view of the Nuyina showing roofs over deck 4 for weather protection.A steel block that will form the starboard bridge wing.A drop keel lying on the ship’s deck.This image shows the crosshair frame for a laser target point, mounted in a ‘gondola’ during alignment checks.A crosshair frame with its laser target point (the bronze cap at centre of frame), mounted in a sterntube bearing, during alignment checks of the sterntube inside the gondola.Two dry cargo holds sitting forward of the bridge.One of the two 55 tonne lift-capacity main cargo cranes that will sit forward of the bridge.The 92.1 square metre dry provision food store on deck 3.The bow of the ship rising above deck 4 surrounded by scaffolding.

The propeller shafts of Australia’s new Antarctic icebreaker, RSV Nuyina, have recently been installed with laser-precision alignment.

The 50 metres-long propeller shafts are connected to the main engines in the centre of the ship and the 40 tonne propellers at the stern.

The shafts each sit inside a ‘sterntube’, which allows them to pass through the hull without water leaking into the ship.

Icebreaker Project Manager, Mr Nick Browne, said the alignment process involved sending a laser beam through the sterntubes.

“Perfect alignment of the propeller shafts is critical to prevent propeller wobble and structural failure of the shafts, and helps ensure the silent operation of the ship during scientific surveys,” he said.

“In open water the main noise on the ship is from the propulsion system — the engines, gear boxes and propellers.”

“This interferes with scientific acoustic instruments and can affect the behaviour of fish and other marine organisms that the scientists want to study.”

To operate in silent mode the ship will switch its power source from diesel engines to quiet electric motors, powered by diesel generators on flexible mounting systems.

“The electric motors are mounted on a flexible coupling that absorbs vibrations, and the diesel generators are also installed on elastic mounts to stop the noise being transmitted down the hull and into the water,” Mr Browne said.

The propellers, in combination with the hull shape, have also been designed to reduce bubble formation and movement, which create noise when they pop or flow over the acoustic instruments.

As the ship takes shape in the Damen drydock in Romania, a number of distinct workspaces are now visible.

These include the two main cargo holds, which can each carry the equivalent of 50 20-foot shipping containers, the ‘dry provision store’ for food, and the scientific wet well, where krill and other marine organisms will be directly sampled from the ocean.

A range of blocks belonging to the ship’s superstructure (the area above the ship) are also under construction beside the ship.

These blocks will be added to the ship once it moves to a wet dock in the coming months.