Monday, October 22, 2012

How Navy deployment schedules work



            In the last debate both candidates sparred over the size the United States Navy. Mitt Romney was right when he said that our navy is the smallest it has been since World War One but President Obama was also right when he said that size isn't the only factor, capabilities matter too. The question then becomes, just how many ships do we need? So, I thought I'd emerge from hibernation to write up this blog post, one that has been rattling around in my head for quite a while.

            Before I start let me say that I am NOT giving an opinion on how many ships we need or what kind of missions we should be doing. I will only be dealing why the navy has the number of ships it has based on how it functions. Policy and missions are totally different issues and not something I want to deal with now. With that disclaimer out there, let's get started.

            Right now the US Navy deploys ships in one of three ways, carrier battle groups, amphibious assault groups, and single deployments. Most of the navy is deployed in either carrier battle groups or amphibious assault groups. It is less common for major warships to be deployed on their own. That just isn't the way they are designed to be used.

            The carrier battle group is the most capable and diverse force the navy musters. A common saying is that whenever a crisis erupts around the world, the President asks where the aircraft carriers are. And whenever a US carrier pulls up to an area in crisis with it's escort force, it is quite often the most powerful military force in the region. That fighting ability can scare our enemies into backing down and reassure our allies that we have their backs. So our carriers are very useful but we have eleven right now. We have one more under construction and another one that will be retired very soon. So again I'll ask, why do we need so many?

            The reason why we have so many carriers and why some want more is based on deployment needs. A carrier can only be in so many places at once, even a carrier that runs on nuclear power. So, if there are two areas you want a carrier to be floating around in, you need two carriers, right? Well, no, not really. Before I explain let's look at this historically.

            Back in the 1980s the navy wanted a carrier battle group always on station in a few areas. One carrier had to be in the North Atlantic by Norway. Another had to be in the Mediterranean. It was always nice to have a carrier in or near the Persian Gulf but that Mediterranean carrier could always switch back and forth by running through the Suez Canal. And a carrier had to be in the Western Pacific to watch the Soviet bases in Kamchatka. So that makes four deployment areas. But Reagan wanted 15 carriers, why?

            Because as a general rule to have one ship on deployment you need a total of three. One will be on deployment, one will be working up or heading to the deployment zone, and one will be in dry-dock getting all fixed up. That might seem a bit extravagant to some, but it is the best way to get the most out of ships and crew. Let's look at each step of that deployment cycle starting with the dry-dock.

            Warships are hideously complicated machines. The largest ships in the US Navy, Nimitz class nuclear powered carriers, weigh about 100,000 tons, are about 1,000 feet long, and require a crew of 6,000. They have two nuclear reactors, vast fuel tanks for the planes they operate, miles and miles of electrical cable and network cables, and all the infrastructure to keep those 6,000 people alive and happy. All that stuff breaks down constantly and has to be repaired.

            Some of it can be repaired at sea but sometimes bigger stuff breaks or wears out and then the ship has to be fixed in port. After a six month deployment, a carrier might be out of service for another six months or so. While in dock, equipment is also upgraded. It is important to consider the fact that a nuclear powered carrier has a service life of 50 years. When Enterprise was launched, Kennedy had just been elected and Nimitz was built during the Ford administration. Technology has changed considerable since then and these ships need advance with the times.

            In addition to regular upgrades, carriers get a mid-life servicing. This takes two years or so because the reactors need to be refueled and that requires basically taking half the ship apart and putting it back together again. So about once every five years a carrier will be out of commission for at least two years. I say once every five years because we build a new carrier about once every five years. But lets get back to that regular repair.

            Each carrier spends about six months a year swinging at anchor getting fixed up. It is useless during that stage. Once it is all fixed up it's ready to deploy, right? Nope. During that downtime the crew has lost their edge. Some of them have left for other ships and their replacements might have arrived straight from basic. Some of them have just been promoted and are doing a new job. They need to take a few weeks or so working up just off-shore so they can remember their jobs. And then once the ship is done working up it goes straight back to the dock to fix all the stuff that broke during the workup. That might take another couple weeks. Now the ship is ready to deploy.

            But it doesn't magically get from San Diego to the Indian Ocean, the carrier may take a few weeks getting there. And there, it floats around for three months or so doing carrier related things. It's planes fly patrols, hunt pirates, watch the Iranians, and do all sorts of other interesting and exciting things. And then it returns home, again taking a few weeks. So let's add this all up.

            Our carrier has spent three months on deployment, a month going to and coming back from deployment, a month or so working up for deployment, and six months at least fixing all the stuff that broke on deployment. That means eleven months has passed and it spent about three months on station. That's how I came to that three ships supports one ship on deployment idea earlier. But there is something else which is very important to the size of our fleet. So far we have only looked at carriers.

            A carrier is a huge investment. It must be protected at all times and to protect it we surround it with cruisers, destroyers, and submarines. Generally there will be around four to six missile equipped surface ships and one or two attack submarines to keep enemy subs away. All of those ships have similar deployment issues. In many cases, they need even more time between deployments because they are smaller and more specialized.

            Now let's start adding numbers up. As a basic number, I'll go with the idea that we only have one area of interest to cover. That means we need three carriers with their own battle groups. So we have three carriers, twelve to eighteen missile ships, and three to six submarines. That is a minimum number for a navy that is tasked with watching one area on the planet constantly. Every time you add a new area, increase the fleet by those numbers. But, carriers and their battle groups aren't the only kind of way our ships deploy.

            The second method is in amphibious assault groups. To make one of these, you need to take a couple ships which carry around Marines and all their gear and a couple missile equipped ships to protect them. Generally there will be seven ships in a group like this. We have three different kinds of amphibious assault ships and a group will have one of each. The first is a helicopter assault ship and it looks like a small aircraft carrier. It carries lots of helicopters, a few Harriers, a few hovercrafts, and lots of marines with their trucks and tanks. Next is the landing ship dock with doesn't carry a lot of troops or vehicles, but does carry a lot of small landing craft to move marines from their ships to the beach. And finally is the amphibious transport dock, which also carries a lot of smaller landing craft but can also carry helicopters along with lots of gear and marines.

            In addition to carrying around a better army than most countries can muster, amphibious assault ships carry very good hospital facilities and can help with disaster relief. And the three to one rule applies just as much to these ships as it did to carriers. So lets do some more math. For that one deployment zone, we need around 50 ships to keep a carrier battle group and an amphibious assault group on constant deployment. That is the higher number but it shows just what is required. And don't forget, we send ships off on their own occasionally too.

            As for individual deployments, the vast majority of those are attack submarines and nuclear ballistic missile submarines. Yes, we still have submarines with lots and lots of nuclear missiles ready to launch at a moment's notice prowling the oceans. And attack subs are the ultimate loner in the navy. During the Cold War, attack subs followed Soviet ships and watched Soviet exercises. So we need a few of those to add to that 50 number from above.

            So what does this all mean? Do we need three hundred ships? Maybe. But if we want to keep watch on a few parts of the world constantly, then the number of ships required balloons dramatically. Remember to keep an area constantly covered by a carrier group, we need three carriers and almost one hundred other ships. If we just want to send ships out on a world tour on occasion, then we can make do with a whole lot less. 

-Mike

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