Dome repairs found impractical

Close inspection by the team shows the damage to the sonar dome. Photo courtesy DSTO

DSTO got a chance to display its expertise in underwater ultrasonic testing earlier this year.

As HMAS Anzac (CAPT Peter Lockwood) was returning from service in The Gulf, she reported likely damage to her sonar dome.

The dome is critical to protecting the ship’s sonar array. As the dome is positioned under the water line, off-shore repairs are impractical and somewhat limited. Docking is usually required to achieve repairs or replacement of the dome.

Photos and reports provided by Anzac’s divers showed that the situation was not critical but that an inspection should take place immediately upon the ship’s return to Australia.

DSTO became involved when HMAS Anzac’s Systems Project Office (SPO) contacted Lloyd Hammond (MPD Stirling). The SPO’s main concerns were the unknown extent of the damage sustained, the high cost of a replacement dome, the potential availability of a replacement and the cost implications associated with docking.
Anzac was not due for a docking for several years.

A thorough inspection of the sonar dome was carried out by a team of specialists at Fleet Base West. Put together by Lloyd Hammond the team included his DSTO colleagues, Robert Ditchburn and Nigel St John, as well as specialist underwater ultrasonic inspection contractors from Global Offshore.

Unfortunately, the report prepared by the inspection team concluded that there was no option but to replace the dome. The damage sustained was too great to repair underwater.

What the team could not determine with any certainty was what had caused the damage in the first place. It is possible, given the area where Anzac had been deployed, that a stray submerged container had hit the dome but a definitive cause is likely to remain elusive.

Meanwhile, Anzac has been docked while a new sonar dome is fitted.

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