Nuclear submarines are to conventional ones as machine-guns are to muskets

Telegraph

2 days ago

So, we and the Australians have reaffirmed our commitment to the Aukus pact, the central element of which is that Australia will get a force of nuclear powered but conventionally armed submarines. Down the road, the plan is that there will be a jointly developed Australian-British submarine class, which will follow on from the current British Astute class boats.
But Britain must first – with very great urgency – finish building the Astutes and then get cracking on our replacement nuclear deterrent submarines. Our current Trident subs are now so old, and their support infrastructure so messed up, that getting the next one ready to take over from the one setting out on patrol can take six months – putting an intolerable burden on our submariners.
We don't have the industrial base or the funding to build two classes of submarine at once, so the Brit-Aussie subs will have to wait, probably for quite a long time. Thus, under the Aukus plan, the first few boats for Australia will be US made Virginia class subs. Unfortunately that part of the plan was always a little problematic, as the US industrial base is also creaking.
The US Navy has the money to buy two new attack submarines a year, which assuming a 30-year lifespan would sustain a fleet of 60. But US yards have only managed to produce an average of 1.2 Virginia s per year in recent times: the American attack-boat fleet is shrinking, and is now down to 53. While this seems like a huge number to a former Royal Navy man like me, and I would suggest that the USN can easily spare a few hulls for the land Down Under, to Americans the prospect of having a measly 50 attack boats in service – or even fewer – is a horrifying one.
Now President Trump has launched a review of the Aukus deal, which could see the US pull out. That might torpedo the whole plan, as Australia cannot afford to wait decades to get some new submarines. Before the Aukus plan was announced, it had been thought that the Aussies might buy conventionally-powered boats from France, and the Aukus plan has never lacked for opponents in the US, the UK, Australia – and France, of course.
But there are a few things that enemies of Aukus might consider. The first is the absolutely enormous difference between conventionally-powered and nuclear-powered submarines. They are both called 'submarines' but that is hugely misleading. It's a bit like saying that a musket and a machine-gun are both firearms.
The standard form of conventional sub has diesel-electric propulsion. It's essentially a somewhat modernised version of the German U-boats of World War Two (and One). Diesel engines need air to run, so when the boat is submerged it has to use electric motors fed by a bank of batteries. It cannot move fast like this except very briefly, nor can it go very far even at a crawl. It has to put up a 'snort' air-intake mast at regular intervals for long periods of time to recharge its batteries if it is to go a long way, and if it wants to go that long way at any reasonable speed it has to surface completely. Doing either means it is easily found using radar. A conventional submarine is therefore unlikely to last long under the footprint of hostile radar-equipped aircraft – as indeed the U-boats did not, back in the day.
By contrast a nuclear boat can stay fully down for months on end, going at any speed it chooses the entire time. Only a complex system of specialist assets – seabed sensors, enemy nuclear subs, specially equipped anti-submarine warships and aircraft, all working together – has any chance of locating and tracking it. Its heavyweight torpedoes can sink any ship: its cruise missiles can strike targets ashore from a thousand miles away. It's a game-changing weapon, and a nation with nuclear subs is a hugely more dangerous opponent than one without.
It's true, there are various so-called 'air independent' enhancements which can be added to conventional boats. These involve using tanks of oxygen to run various different kinds of auxiliary propulsion while submerged. The mainstream method is hydrogen fuel cells, but some nations prefer Stirling-cycle engines as these can be run on the boat's ordinary diesel fuel while the oxygen lasts. France, uniquely, has developed the 'Module d'Energie Sous-Marine Autonome' (MESMA) system, which is an ethanol-powered steam turbine. It's considerably more powerful than the other air-independent options, but it apparently lacks endurance and makes a lot of noise. The only nation which actually uses MESMA is Pakistan: France doesn't, of course, as it has proper nuclear boats.
All the air-independent options are always installed alongside conventional diesels, which gives a good handy hint as to just how useful they are. None of them come anywhere close to the capability of a nuclear boat, and they require recharging with oxygen and usually one or another kind of exotic fuel as well: they can't do this at sea, or even in most harbours or naval bases. A nuclear boat, by contrast, runs for many years without refuelling and makes its own air and water: all it needs is supplies of food for the crew every few months.
If Australia and its friends are going to tip the Pacific balance of power in their favour, it's nuclear submarines that are needed, not any kind of conventional ones. That means Aukus.
The second factor in favour of Aukus is basing. When it comes to facing down China a submarine based at Perth in Western Australia has a lot more effect than one based on the US West Coast, and enormously more than one based in the Atlantic. The first element of the Aukus plan – before even the transfer of Virginia s to Australia – is the basing of a British Astute and some USN boats at Perth. This is planned for this decade, and will appreciably change the parameters of wargames modelling a Chinese invasion of Taiwan.
Elbridge Colby, the man in charge of Trump's Aukus review, is a known China hawk. If he's serious about that he'll realise that the Perth base is a good thing on its own. Getting that base is well worth leasing a few Virginia s to the Aussies, especially as it brings a British Astute into the Pacific in the near future, and a new friendly fleet of UK-Australian boats further off. From the American point of view, Aukus is a rare case of some Western allies actually pulling their weight on defence – something President Trump and Secretary of Defence Hegseth are vocally in favour of.
As Tom Sharpe of this parish has put it: ' The free world needs a fleet of nuclear submarines based in Australia '.
Aukus must succeed.