Would Australia Buying French Rubis (SSN) Submarines be Viable?

KQN on October 22, 2018 raised the interesting comment that:

"There is also the option of acquiring the small and proven Rubis class. The French would need to re-start its production which should not be a problem. Re-fueling is still an issue as well as local political considerations."

Pete's Response

The interior design of the Rubis is a mystery with no interior diagrams that Pete has seen. Odd for such an old sub. All I can offer is this diagram courtesy Pakistan Defence forum.

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However there are some Youtube videos which give partial views of Rubis interiors. See this Youtube from 45 seconds on, starring the Rubis submarine Perle, visiting Jacksonville, Florida in 2011. The Youtube seens imply the small size of this submarine class makes it very crowded and uncomfortable for the 70 officers and crew on lengthy missions. At 3 minute, 20 seconds, surely the periscope and red goggle restrictions could be replaced with photonic masts!

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The Rubis is small, at 2,400 tons surfaced - 2,600 ton submerged (right sidebar). The Rubis only carries 14 Heavyweight (HW) shots - torpedoes and/or missiles. This suggests the French Navy had to make severe compromises between the Rubis small 14 shot warload and other essentials such as accommodation for a relatively large crew of 70, food, reactor and sonars, etc. 

With only 4 torpedo tubes much space may be allotted to a bow sonar. Nuclear propulsion notwithstanding, food in Rubises may be limited to 45 days.

For most navies succeeding submarine classes are steadily larger, carrying more HW shots - now with the additional requirement of land attack missiles and soon UUVs. In comparison Australia's Collins subs already carry 22 HW shots.

The Rubis' have a limited submerged speed of only 25 knots, lower than the 30+ knot requirement expected of SSNs.

Its Rubis' 7.6m Beam (right sidebar) accommodates the K48 (48MW of power) reactor. The Rubis would be unable to accommodate the updated K15 reactor which requires a beam of at least 8.8m.

Since the 1970s, when the Rubis was launched anti-submarine sensors have improved greatly in performance, meaning active and passive quieting measures (which add weight and size) are all the more important. Highly relevant are Canada's 1980's reasons for not choosing the Rubis:

"The Rubis-class as designed failed to meet the Canadian Statement of Requirement (SOR) as it was noisy underwater and slow. It also came with the caveat that the first 4-5 submarines would have to be built in France. [But] Unlike the British Trafalgar-class [presumably the UK Astute class would have the same legal problems], the Rubis design did not require USA permission to transfer the nuclear propulsion technology, as the Americans were certain to invoke their veto of the sale to Canada."

Yes, the need to refuel in France every 7 - 10 years constitutes a major downside for Australia choosing the Rubis or Barracuda. At Peter Lobner's "Marine Nuclear Power 1939-2018" at  is Marine Nuclear Power 1939 – 2018_Part 4_Europe & Canada which states on page 197:

"Unique French nuclear safety rules have resulted in naval reactor operating cycles that are substantially different than in US and UK naval plants. 

Following nuclear safety practices established by the French civilian nuclear safety authority ASN...the defense nuclear safety authority DSND...requires that all reactor pressure vessels be inspected from the inside every 10 years using a dedicated inspection machine and requires the withdrawal of fuel assemblies and all the internal components of the reactor pressure vessel. These pressure vessel inspections are performed during each major overhaul (an IPER) of the nuclear-powered ship, which typically occurs at 8 –10 year intervals."

So all in all the Rubis would fall short of Australia's modern warload and quieting requirements and even the Barracuda may fall short on refueling in France realities.

Pete