• The Virginia-class attack submarine. (US Navy)
    The Virginia-class attack submarine. (US Navy)

Now it’s been decided that the RAN is to acquire a fleet of nuclear-powered hunter-killer submarines (SSNs), the question is – which one?

Given that Australia’s technology partners in this nuclear enterprise are the US and the UK, the choice comes down to the US Virginia-class, the UK Astute-class or – unlikely but who knows – perhaps an Astute-class boat fitted with a US combat management system and deploying US weaponry.

Some Australian-specific customisation to either class could be involved, but it’s hard to envisage the acceptability of anything but minimal modifications to a proven in-service design when moving to the nuclear option is adding years to what was already an unhurried Attack-class schedule.

Nothing is ever simple, and a further complication is both the US and the UK have now initiated programs for their next-generation successors to the Virginia and Astute classes.

The timing of the US SSN(X) and UK Submersible Ship Nuclear Replacement (SSNR) programs ensures their relevance to Australia, probably not as potential platforms but featuring enhanced capabilities capable of inclusion in late-build Virginia-class or Astute-class boats.

The first nuclear boat for the RAN is expected to be completed around 2035, completion of the first US SSN(X) is scheduled for 2031, while a firm timeline has yet to be disclosed for the SSNR, but it’s likely to be required around 2035 when first-of-class HMS Astute completes 25 years of service.

Under the US Navy’s current shipbuilding plan, the final four of 39 Virginia-class submarines will be procured in 2032 and 2033. The seventh and final Astute-class boat will be commissioned in 2026.

Both types represent the cutting-edge of Western hunter killer technology.

A Virginia-class submarine is 115 metres long, has a 10.36 metre beam, displaces 7,900 tons, has a submerged speed of more than 25 knots, and a 134-strong crew. The boat is powered by a single General Electric pressurised water nuclear reactor and a pump jet propulsor (developed by BAE Systems for the UK’s earlier Swiftsure class SSNs).

In terms of weaponry, a Virginia boat deploys two Virginia Payload Tubes (VPTs), each with six cells for 1,700km range UGM-190 Tomahawk Block IV land attack cruise missiles, and four 21” torpedo tubes for Mk-48 ADCAP torpedoes or mines. The final eight (Block V) boats of the class will feature a new Virginia Payload Module (VPM) mid-body section housing an additional 28 Tomahawks, boosting Tomahawk inventory to 40, boat length to 140 metres and displacement to 10,200 tons.

An Astute-class submarine is 97 metres long, has an 11.3 metre beam, displaces 7,000 tons, has a submerged speed of up to 30 knots, and a 98-strong crew. The boat is powered by a single Rolls Royce pressurised water nuclear reactor and a pump jet propulsor.

In terms of weaponry, an Astute boat has six 121” torpedo tubes with stowage for up to 38 Spearfish heavyweight torpedoes and/or UGM-109 Tomahawk Block IV land attack missiles.

According to the US Congressional Research Service, the latest Virginia-class Block IV costs an estimated A$4.4 billion. The UK National Audit Office prices an Astute-class boat at A$2.6 billion. 

As experience has shown, construction in Australia in whole or in part could be expected to add significantly to those amounts.

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