How to build a fort


Verified SOF
Jan 15, 2008

Foreign military bases have both political and practical difficulties. “Seabasing” may offer a solution
BASING troops and equipment on foreign soil is fraught with difficulty. Even friendly countries can cut up rough at crucial moments, as America found when Turkey restricted the use of its territory and airspace during the invasion of Iraq in 2003. In an occupied country the situation is worse, as a base is a magnet for attacks. Nor can you always put your base where you need it. If a country does not want to host it, and cannot be bribed to, that—short of invasion—is that.

But no one owns the high seas, and partisans rarely have access to serious naval power. So America, still the world’s only superpower and thus the one with most need for foreign bases, is investigating the idea of building military bases on the ocean. They would, in effect, be composed of parts that can be rearranged like giant Lego bricks. The armed forces could assemble them when needed, add to them, subtract from them and eventually dismantle them when they are no longer required—and all without leaving a trace.

Constructing such bases is a formidable technological challenge. Not only do you have to provide quarters for servicemen, but you also have to handle, store and retrieve large amounts of supplies and weapons without access to dockside cranes. Shuffling the containers carrying these, so that those needed immediately are accessible, is akin to solving a moving-block puzzle where the blocks weigh many tonnes each. But America seems committed to the idea, and the first seabases should be deployable within a decade.

Basic thinking
The original approach to seabasing was extremely Legolike. Modular rafts—platforms mounted on pontoons—would be linked together by hinges to create large, flattish surfaces that could nevertheless bend with the waves. Such a system was tested in a peacetime operation off the coast of Liberia in spring 2008. Instead of armaments, hospital supplies and the materials to build a school were unloaded from a ship to the platform, and thence to landing craft which disgorged them onto a beach.

The experiment worked, but there are doubts about taking it any further. One question is how such a raft of rafts would stand up to severe weather. There is also scepticism about whether the original goal, a surface large enough to create a floating runway that could accommodate transport aircraft, is either financially or physically feasible. It would be far larger than the largest aircraft-carrier now afloat, and thus expensive to build, and it would have to be both rigid and stable enough to act as a runway and flexible enough to withstand rough seas. The difficulty of squaring these requirements has led designers to abandon the idea of strict modularity in favour of a system that uses an array of more conventional but still specially designed ships. According to Robert Button, a seabasing expert at the RAND Corporation, a think-tank, America’s navy plans to build 35 ships designed for seabasing over the next decade.

The core of such a ship-based seabase would be something known, in the strangulated jargon beloved of military men, as the Maritime Pre-Positioning Force (Future). America’s marines already use pre-positioning supply ships as floating warehouses. The 14 ships in the new replacement class will continue to store supplies in this way. But, in addition, they will have room to berth 2,000 servicemen, or between 20 and 30 vertical-take-off aircraft, or hundreds of ground vehicles. More impressively, each ship will carry a folding bridge, about 30 metres long, to connect it to its neighbour. These bridges—regarded as the linchpins of seabasing—will remain stable in swells of up to 2 metres. They will allow vehicles the size of lorries to drive from one ship to another.

A second element of this form of seabasing is the “mobile landing platform” (MLP), a ship longer than two football pitches, with a large, flat platform. This will make it easier for other vessels, including pre-positioning ships, to load the MLP at sea using cranes and bridges. It will accommodate almost 1,500 servicemen, and ferry them to combat zones along with at least six small landing craft or hovercraft, numerous tanks and lorries, and a small number of vertical-take-off aircraft. One feature of an MLP will be that it can partially submerge itself by pumping water into tanks within its hull. Hovercraft will therefore be able to embark and disembark easily. And a modern hovercraft can carry an Abrams tank, America’s heaviest, at a speed of 40 knots.

The cleverest part of a new type of seabase, though, is the mundane matter of having a place for everything, and everything in its place. Most of the stuff on the base will be kept in standard shipping containers until required. War being war, though, it is not always obvious in advance what will be needed when. And if you find that some crucial piece of equipment is in the middle of the bottom of a stack rather than the edge of the top, and you need it in a hurry, you have a problem.

Logistics, logistics, logistics
To deal with this geometric puzzle the defence department paid BEC Industries, an engineering firm based in Florida, to design a special container-management system. The firm completed this system, known as GRID, in February.

In essence, GRID is a way of unburying containers. A winch shuttles back and forth, and side to side, on a grid of rails above stacks of containers. The equipment works rapidly, repositioning half a dozen containers in ten minutes. (A traditional crane might move that many in an hour.) Software determines the most efficient way to rearrange them. Removing just two dozen containers from stacks aligned in rows can involve hundreds of repositionings. Each decision about which container to move next, and where to place it, has implications for the number of times all the other containers must be moved later. According to Brian Pfeifer, the project’s chief engineer, working out the shuffling logic was the most complex part of the project. The first example of GRID will be installed on a warship this year.

Cranes will still be needed, though, to load the pre-positioning ships from supply vessels. That is always going to be tricky in anything other than a dead calm. As Ed May, a crane expert at Oceaneering International, an engineering company based in Houston, Texas, observes, the trick is for the crane operator to wait until the ships’ movements position the load over the right spot, and then “set it down real quick”. Or, in non-technical jargon, drop it.

Dropping it accurately may also be easier in the future. By measuring the motions of nearby waves and vessels with radar and lasers, the software running a crane can predict exactly how a ship will be pushed, and react accordingly. A crane developed by America’s Office of Naval Research (ONR) in collaboration with Oceaneering and Siemens, a German industrial giant, automatically adjusts its position to compensate for ship movements the moment they begin. The ONR will test the system at sea this autumn.

“Logistics, logistics, logistics” is a mantra of seabasing. It is, perhaps, a less catchy slogan than “shock and awe”. But warfare—or even a formidable threat to attack—begins with the movement and stationing of troops and kit. If you can bring your own base with you, that threat is more credible and easier to make.