Australia’s future submarine, but which one?
26 Feb 2013|

Last week ASPI and the Submarine Institute of Australia sat around a table for a day to discuss the rationale for the future submarine. The aim was to set out as clearly as possible what each team thought about the role of submarines. Note that I didn’t say ‘both sides’—it wasn’t a debate between opposing factions, but an exercise in understanding the shared and disputed spaces in the argument. We didn’t reach a definitive result—and I’m not sure that’s even possible given the subjective nature of the judgements required—but we got to a point where there was agreement about a wide range of issues and disagreement on only a few.

For example, we quickly agreed that submarines have some capabilities that can’t be easily replaced by other platforms. I think the readiness with which we agreed to that surprised our SIA colleagues, perhaps based on a slight misreading of my previous blog post in which I suggested several other ways to do some of the things that subs do. But my claim wasn’t that the alternatives were the same—and Peter Briggs did a good job of explaining the differences last week—but that some of the submarines capability was replaceable by other means.

It also didn’t take long to agree that big submarines are more capable than small ones. That shouldn’t be a surprise. After all, a submarine’s payload is proportional to its overall weight, typically a little under 10%. That payload has to include the fuel required to get to the patrol area and stay there for an operationally useful time. It also includes all of the weapons it might need and the provisions the crew will get through during the voyage. As well, if the patrol area is far from base, the boat will use a lot of its endurance in just getting there, unless it has a fast transit speed. But the higher the speed, the more fuel required, in something of a vicious circle.

So any future decision to scale back the size of submarines for reasons of reducing the cost and/or the engineering and project risk would cause a hit to capability. That needn’t be fatal to the cause of smaller submarines, as we’ll come back to later, but it has to be acknowledged. If we bought submarines smaller than the Collins, in some respects we’d have less capable submarines than we do now. Conversely, nuclear submarines have payload, range, speed and endurance capabilities greater than even the largest conventional submarines. If we could manage the very substantial difficulties we would have in acquiring and operating them, we’d end up with more submarine capability than we have now.

This actually brings us to several logical fallacies often seen in the public submarine debate. At one end, we find those who assert that off-the-shelf submarines could meet Australia’s strategic needs just as well as the larger Collins class.

That simply isn’t the case. The European submarines, for all of the reasons explained above, don’t have the same capabilities as larger boats. They offer a lower level of capability, albeit at a lower cost and much lower project risk, so the case for them necessarily has to be based on a different cost benefit calculus. At the other end, we find the argument that nuclear submarines offer too much capability for Australia.

The fact is that the more capable the submarine, the more military options it potentially  has. The trick of course is to work out how much it costs to get and maintain that capability in relation to the options it provides. Those costs are crucial, because they displace other military options within the defence budget, and other national options more generally. And that’s where our view and the SIA differed most noticeably. We didn’t accept that demonstrating the unique abilities of submarines and the relative effectiveness of large ones was sufficient to make a case for building  them. Nor do we accept that the unquestionably superior qualities of large submarines over small ones means that the latter should be ruled out.

Instead, we simply continue to argue that it’s necessary to have, on the one hand, the military options that submarines of different kinds provide and at least a qualitative understanding of the benefits they could bring in various scenarios. On the other hand, the costs need to be understood as well, and weighed against the potential benefits. The SIA have made this judgement and have come down on the side of large conventional submarines (PDF). We aren’t so sure that the case has been made. In a later post I’ll examine the questions that have to be answered to make the case as we see it.

Until then, here’s a simple way to understand that such a process is necessary, using the method of ‘limiting cases’. At one limit, if submarines were free, there’d be no trouble deciding to get some. After all, there’d be no opportunity cost, and the benefits they brought wouldn’t have to be likely to be required—we’d keep them around just in case they were useful. At the other limit, if they were a trillion dollars each we’d have little difficulty deciding that we’d live without their capabilities and find some other ways to insure our security through military and other means. The real world isn’t kind enough to present such idealised choices, of course. That’s why we have to think through our options and opportunity costs as carefully as possible.

Andrew Davies is a senior analyst for defence capability at ASPI and executive editor of The Strategist.