I have engaged in a series of conversations on twitter about the Royal Canadian Navy's sub force. It currently stands at four with perhaps one being operational. Canada bought four of these subs from the UK, and then found out that they were more than just a bit broken (which is perhaps why my house-hunting has turned to focus on much newer construction). Anyhow, the question I have been pondering is: how many subs would be enough for Canada?
My basic ill-informed view* is starts with some basic facts: Canada has three coasts (Atlantic, Pacific, and way the hell up north); that subs move slowly so that a sub based on one coast cannot be counted on for helping out elsewhere; that you need at least two subs in the force to have one deployable subs since they require a heap of maintenance (and break down much as we have found out).
* most of what I have learned about subs comes from reading books about the American experience in the Pacific during WWII.
If one assumes that having one sub at sea per coast is sufficient (I will get to that in a second), then the math suggests six subs at the very least unless one does not care about the Arctic. Ooops, the entire justification these days for the burst of spending is Arctic Sovereignty. So, the six subs math assumes that one sub can cover an entire coast. This is, of course, entirely unrealistic since subs do not move swiftly, but perhaps they can provide added value if combined with other naval resources (satellites, sonar networks, etc.)
But this gets to the big question--what is a sub good for? My twitter friends have argued that you just need the potential for a sub to be in the neighborhood to have a deterrent effect, just like cops and speed traps. This then leads to back to the question: deterring whom?? Spanish fishing vessels was one example posed by Phil Lagasse. That prompted my response: if the problem are fishing poachers, why not deploy surface vessels? They are far, far cheaper since they don't have to do that sinking and then un-sinking thing that subs do. Yes, subs are harder to find, their primary advantage, but do poaching vessels have the necessary radar to evade surface warships especially if they have helicopters?
No, subs are useful for dealing with the subs of other countries, for dealing with warships from other countries, and potentially vessels controlled by non-state actors (terrorists, drug cartels). Such actors can figure out pretty easily where Canada's subs are based and how many are operational. This information would then allow any actor seeking to penetrate Canadian waters to evade the subs if they are a minimal force, such as one or two subs operating off of each coast. Even if one has a good sonar warning system, you would still need enough subs at sea to respond since subs cannot magically move hundreds of kilometers over night.
So, my basic, ill-informed conclusion is that four subs would be a token sub force even if all could operate, because only two or three would be available at any time even if they were reliable. Canada is simply too big of a country with too much coast line and too much territorial waters to have a token sub force. In my mind, four nearly equals zero since it is not even close to sufficient. Since an investment in a sufficient sub force is unlikely, the question really is whether having a symbolic one is worth the billions of dollars it is costing Canada? As a big fan of subs, I still have to think it is not, given that there are tradeoffs. Money spent on symbolic subs could be spent on capabilities with real added value, like functional helicopters to fly off of the ships that do and will exist.
Update: This British MP's take on the whole thing is pretty striking.