Sunday, December 22, 2013

When Mixing Electricity With Water is Good

Our Navy has an aversion to non-nuclear subs that approaches vampire fear of sunlight. But they have a point.

The reason our Navy likes nuclear subs is something I hadn't really thought about:

Modern diesel electric subs cost 60-85 percent less than nuclear subs and are known to be more difficult to detect in coastal waters and sometimes even on the high seas. Yet all major navies want the nukes. It’s all about energy and the fact that the nuclear boats have a lot more of it. Diesel-electric boats have enough food and fuel on board to stay at sea for about a thousand hours. And that assumes moving slowly (most of the time at a sluggish 10-15 kilometers an hour) and not using a lot of electronics all the time. Nukes don’t have that problem as they have years’ worth of nuclear fuel on board and can generate much more electricity than a diesel-electric boat. Being 3-4 times larger (in terms of displacement) than most diesel-electric boats the SSNs can carry a lot more electronics and run them all the time. This provides an enormous advantage because passive (not broadcasting) sensors are the perfect tool for detecting other ships or subs while you lie quietly below the surface. Those passive sensors work because they use a lot of computing power, which requires a lot of electricity which SSNs have no problem supplying.

I never thought of the power angle. I don't know why this is the first time I'm reading about it.

I've always accepted that we need large boats given our geography. But we built large diesel-electrics in World War II. I've always wondered why at least some of our boats couldn't be non-nuclear to work in restricted, coastal waters. Australia builds big non-nuclear boats compared to the small craft Europeans build for coastal defense.

Sure, if we had even large conventional boats they wouldn't be strategically mobile. But surely there are some areas in the world that could use such quieter (and cheaper) boats, no?

No, it seems. Those modern diesel-electrics appear they can be quieter than nuclear boats in coastal waters only if they are simply hiding and not running their detection gear. If so, that makes their noise superiority over nuclear boats in that environment less than useful.

The post discusses how our Navy has been studying the newest non-nuclear boats to figure out how to find them with all the gear the nuclear boats can run all the time.

I will say that based on this angle, I can fully back the Navy's position that it does not want conventional boats. It's a good argument. I remain perplexed that I don't think I've ever read about this angle before.

It still bugs me that the Navy doesn't even want to know how to build these boats (like, for Taiwan) out of fear that the government would make them build non-nuclear boats as a cheaper alternative to nukes.

But I'm not sure whether I should be more bugged about the Navy or the government for that.