The U.S. Navy Needs Diesel Subs

by Gary Schmitt and Richard Cleary

The U.S. Navy faces a fundamental dilemma: It needs more submarines, but the overall defense budget required to build those submarines is headed south. How should it square this circle?

The answer is that the Navy should procure a fleet of diesel-powered subs. Not only are diesels cheaper than nuclear-powered subs, but they have the advantage of being better platforms for many of the tasks the Navy faces today.

The demand for attack submarines is both quantitative and qualitative. Over the past two decades, for example, China has added more than 40 new submarines. Although they are not equivalent to ours, they still need to be tracked – and that takes numbers. Meanwhile, the list of actual and potential submarine missions, including close-in intelligence, surveillance and reconnaissance, special operations, and blockade and mining, continues to grow.

These growing operational demands are coupled with the exigencies of new undersea requirements. In addition to the deep-sea dives and prolonged blue-water missions that became the staple of submarine operations during the Cold War, there are a number of scenarios today that are focused on the littoral areas, the green water within 100 miles of land, be they in the strait of Hormuz or Malacca, off the shores of Taiwan or in the South China Sea.

It is these missions that often favor diesel submarines. Diesel subs are smaller, stealthier and more maneuverable in tight spaces than nuclear submarines. For example, unlike a nuclear submarine’s power plant, a diesel’s primary engine can be turned off when submerged, reducing noise emission. Indeed, unlike a nuclear-powered submarine, a modern diesel can hide on the ocean’s floor, deadly silent, while monitoring whatever passes over and around it.

And with the advent of Air Independent Propulsion (AIP) technology, today’s diesel subs can remain submerged for weeks at a time. When deployed to bases in the Far East or Middle East, the range and reach of today’s AIP-equipped diesels would put them well within striking distance of critical choke points.

And, using the recent sale price of Germany’s Type 212 subs to Turkey as a point of reference – approximately $500 million versus the $2 billion for a Virginia-class nuclear attack submarine – the Navy would be able to ramp up submarine production without breaking the bank.

The U.S. Navy is not ignorant of the advantages of diesel subs. Time and again, American naval crews have struggled to detect their diesel-electric “foes” at sea. Over the past two years, for example, Peruvian and Chilean diesels have made life extremely tough for the U.S. in naval exercises.

Nor is this new; in a joint training exercise in 2005, a Swedish AIP-outfitted Götland-class sub scored a “strike” on the carrier Ronald Reagan. And, most famously, in 2006 a Chinese Song-class diesel submarine surfaced undetected within striking distance of the carrier Kitty Hawk off Japanese waters.

Building diesel submarines in the U.S. has other advantages as well. There is a growing global market for diesel submarines among allies and partners and it’s work U.S. shipyards certainly could use. In addition, having diesels in the fleet provides an in-house training tool for anti-submarine warfare efforts against other nations’ diesels. It is useful to remember that Russia and China have successfully incorporated both diesel and nuclear submarines into their force structure.

Of course, the U.S. Navy has been dead set against building anything but nuclear-powered submarines for a half-century now. Indeed, one reason the offer of a sale of eight diesel submarines to Taiwan made by President George W. Bush in 2001 has never gotten off the ground is because the Navy brass has feared that any diesel construction in the U.S., even if strictly for foreign sales, might open the door to Congress asking, “Why not for our own fleet?”

In addition to the decades-old, Rickover-induced inertia, the new excuse for not building diesels is the claim that the missions that diesels might usefully perform can be handled with unmanned underwater vehicles (UUVs). Why build a new class of submarine when UUVs attached to nuclear submarines can carry out those tasks?

But while UUVs are a promising idea, “promising” is the key here. Significant questions pertaining to speed, payload, sensors and communication remain.

In what was billed as Defense Secretary Robert Gates’ valedictory policy speech at the American Enterprise Institute on May 24, he noted that “more and more money is consumed by fewer and fewer platforms,” and that, in the future, the department’s “guiding principle … must be to develop technology and field weapons that are affordable, versatile, and relevant to the most likely and lethal threats in the decades to come.”

That’s a spot-on assessment as to why the U.S. Navy needs diesel submarines.

Cross-posted from Defense News.

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