- Author
- A.N. Other
- Subjects
- History - general, Ship design and development
- Tags
-
- RAN Ships
- None noted.
- Publication
- September 2011 edition of the Naval Historical Review (all rights reserved)
The USA government will persist with nuclear-powered submarines as a stand-off delivery platform; it is a requirement that is not mandated by Australia’s strategic or diplomatic policies.
In underwater warfare nuclear-powered submarines are not the answer to everything. In fact there are operational missions for which nuclear submarines are not suited. The size of SSN attack submarines such as the USN Virginia class (length 115m, beam 10.4m, submerged displacement 7,800t) makes it unsuitable to operate in shallow waters or close to or indeed bottom on the seabed. The British SSN Astute class (97m long, 10.4m beam, ~7,000t submerged displacement) and the French SSN Barracuda class (99.4m long, 8.8m beam, ~5,300t submerged displacement) are smaller, but still not suited to operate in littoral – commonly called brown waters – than smaller non-nuclear submarines.
Clearly, the time a diesel-electric submarine is most vulnerable to detection is during the period (known as snorting) required to recharge the batteries. But modern conventional submarines will be built with air independent propulsion (AIP) and high energy-to-weight/volume lithium-ion batteries allowing operations to extend over weeks without surfacing.
In his keynote address at UDT 2009 in Cannes, Rear Admiral Krause of the German Navy described non-nuclear submarines as ‘vehicles of position.’ The former submarine CO explained that ‘…despite advances in sonar technology, detecting and targeting submarines remains extremely difficult, particularly in confined and shallow waters where the salinity of the seas and the presence of thermal zones of variable water temperature make submarine detection a real challenge’. The task of gathering intelligence, surveillance and reconnaissance (ISR) is of growing importance in choke points, shipping lanes and harbours. In Krause’s assessment non-nuclear submarines ‘…prepare a battle space prior to major operations. Before the arrival of high value units, submarines survey the area, identify threats and explore and assess the environment’.
At the same conference the former CO of the French SSN and SSBN submarines, Benoît le Masson, together with naval architect Vincent Geiger, introduced DCNS SSK Andrasta as the ideal submarine for operations in brown waters. After decades of force projections on the high seas, Masson and Geiger said, regional governments are now directing much of their military expenditures for the protection of their close maritime borders. In this, the small (48.8m long, 790t) conventionally powered Andrasta class is the French answer to the demands made on submarines in littoral waters. According to DCNS, she has no equivalent in stealth and manoeuvrability. Making the comparison, Masson pointed out that brown water operations are very attractive for submarines which will find in this space a higher density of targets, will collect a lot of information and conduct operations with Special Forces in highly ‘reactive’ operational conditions: ‘a wonderful hunt area’, he exclaimed.
To operate a submarine at less than 2 knots only meters above an irregular seabed, or to bottom for a prolonged period undetected on the seabed in littoral waters, can only be achieved by a modern, non-nuclear-powered submarine. Notwithstanding the advances made in anechoic tiling and the benefits of ambient noise prevalent in shallow waters, the acoustic signature of the nuclear reactor and its associated appurtenances will rarely be crowded out. The infrared signature of a nuclear submarine is detectable at nearly all sea states as well as on the surface in the thermal structure of wave patterns. Contrasting this, modern conventional submarines are extremely quiet, with very low infrared signature. Equipped with AIP propulsion these submarines can operate at patrol quiet state for several weeks without surfacing. Where their hull is constructed from austenitic steel the magnetic signature is all but non-existent.
The Department of Defence spelled out its future requirements of submarines in its Defence Capability Plan 2009:
SEA 1000 [submarines] will provide Australia with a new and more potent defence capability with greater range, longer patrol endurance and increased capability compared with the Collins class. Key capabilities will be in the areas of anti-submarine; anti-surface warfare; strike; intelligence; surveillance and reconnaissance; electronic warfare; mine warfare; and support to both Special Forces and advance force operations.”
The Department of Defence does not think nuclear submarines will meet these needs. Their reasons would have less to do with the current Labor government opposition to a nuclear selection on ideological grounds than with the operational disadvantages of nuclear-powered submarines. In the Department’s considered view, nuclear submarines would: