The 720-tonne Royal Australian Navy ship berthed at Birch St wharf, Dunedin, yesterday for the first of a two-stop visit to New Zealand.
Commanding officer Lieutenant-commander Andy Duff said the ship was designed to keep ports clear and make sure trade continued to flow unheeded in and out of Australia.
- view slideshow: Australian naval minehunter visits Dunedin
It had not seen active duty since it was commissioned in 2002, but did a lot of training in the event that mines were laid, which was a distinct possibility, he said.
"Mines are on the market cheap and they are easy to lay. You can just throw them off the side of a fishing boat."
Operations officer Lieutenant Ross Clarke said a minehunter was a mine countermeasure vessel that actively detected and destroyed individual mines.
Minesweepers, on the other hand, cleared mined areas as a whole, without prior detection of mines.
Diamantina used a sonar device to detect and classify targets and then sent out divers or remotely-operated vehicles to inspect and destroy the mines, mainly using small charges detonated remotely.
Four of the Royal Australian Navy's six minehunters were either on exercise or training around Australia and two were in the Solomon Islands seeking and detonating underwater weapons left after World War 2, Lt Clarke said.
Junior wharfer officer Sub-lieutenant Adrian Hicks said because Diamantina would be operating near mines, it was designed with a low acoustic and magnetic signature, two common forms of trigger for mines.
For example, it was soundproofed by mounting machinery on shock-absorbent rubber, had a fibreglass hull and used a lot of stainless steel (which has a low magnetic resonance) for other fittings.
The ship had one 30mm cannon and two "radar chaff" launchers.
Radar chaff was a self-defence radar countermeasure.
In a war situation, a small rocket would be fired, exploding hundreds of metres from the ship and spreading a cloud of small, thin pieces of metal which appeared as a cluster on radar screens or swamped the enemy's screen with multiple returns, confusing them as to the ship's location.
Lt-cmdr Duff said the ship's crew of 44 had recently completed an international exercise in Australia and was making a stop in Dunedin, and one in Wellington, as part of a neighbourly exercise and for the crew to take rest and relaxation.
Many of the crew were heading to Queenstown yesterday, before returning to Dunedin tomorrow to take part in Remembrance Sunday activities.
The ship, which will be alongside until Monday, is not open to the public.
HMAS Diamantina
Class: Huon
Displacement: 720 tonnes.
Length: 52.5m.
Beam: 9.9m.
Armament: 1 x 30mm DS30B gun; 2 x Sutec Double Eagle mine disposal vehicles.
Features
- Unique hull design with outstanding shock resistance; low magnetic signature which allows the ship to operate in hostile mine environments.
- Single skin monocoque hull designed with no ribs, frames or stiffeners, avoiding stress points that could separate under shock conditions.
- Has variable depth sonar capable of detection ranges more than 1000m ahead of the ship.
- Fitted with pair of Double Eagle mine disposal vehicles, equipped with closed-circuit low light television camera and close-range identification sonar.
- Commands relayed via fibre optic link, which also relays sensor images to ship's operations room.
Source: Royal Australian Navy
