U.S. Submarines: Run Silent, Run Deep...On Diesel Engines?

"Underway on nuclear power", radioed the skipper of USS Nautilus in 1955, after taking history's first nuclear-powered attack submarine to sea for the first time. Nautilus's maiden cruise left an indelible imprint on the navy. Her success, cheered on by the likes of Admiral Hyman Rickover, the godfather of naval nuclear propulsion, helped encode the supremacy of atomic power in the submarine force's cultural DNA.

Things were never the same after that. America built its last diesel-electric sub, once the state of the art, not long after Nautilus took to the sea. Not since 1990 has the U.S. Navy operated conventionally powered boats. It's been longer than that since they were frontline fighting ships. For a quarter-century, then, it's been all nukes, all the time. No U.S. shipbuilder even constructs diesel boats nowadays.

That was then. Now may be the time to break up the nuclear monopoly. To wit, imagine permanently forward-deploying a squadron of diesel attack boats, or SSKs, to likely hotspots. Such a force would expand America's silent service, reversing the ongoing slide in numbers of hulls. It would do so at reasonable cost in this age of budgetary stress. A standing East Asia squadron would be close to the action. Likely based in Japan and Guam, it would amplify the U.S.-Japanese fleet's prowess vis-á-vis China's navy and merchant marine. It would empower Washington and Tokyo to deny China access to offshore waters without committing the whole fleet of U.S. nuclear-powered boats to the endeavor. And in the process it would open up new vistas for building and reinforcing alliances.

Greater numbers, middling cost, a heavier punch in battle. That's a major contribution from such humble craft. U.S. submariners' diesel-propelled past could be, and should be, part of their future.

There's nothing new or especially radical about conventional U.S. subs' prowling the Western Pacific deep. They did so to devastating effect during World War II. For instance, the Philippine Islands was home to the largest concentration of U.S. submarines in the Pacific on the eve of hostilities. U.S. commanders squandered a golden opportunity to run wild against transports carrying Japanese troops to invade the Philippines. But their missed opportunity doesn't detract from subs' potential to confound opponents amid Asia's intricate nautical terrain. It's an exception that proves the rule.

And indeed, American submarines vindicated their potential in ensuing years. U.S. Pacific Fleet boats were among the first vessels to return to Asia following the Japanese raid on Pearl Harbor. Ordered to sea while the battle line was still ablaze at Ford Island, they helped dismember an island empire. Empires like Japan's depend on ships to ferry all manner of warmaking materiel—raw materials, foodstuffs, finished goods—hither and yon. Take away seaborne movement and you cut the lineaments binding the imperial enterprise together.

The submarine campaign grew more and more effective as the U.S. offensives undulated across the Central and South Pacific. U.S. Navy, Marine and Army amphibious forces wrested outer islands from Japan, letting the navy position, maintenance and logistics outposts closer to the foe. Submarine tenders—floating repair and supply depots for all intents and purposes—staged support operations westward of Hawaii. As the transpacific campaigns progressed, boats wasted less time transiting to and from assigned hunting grounds. They spent more time strewing the seafloor with enemy merchantmen and men-of-war.

Forward bases, then, offset the tyranny of distance—allowing the submarine force to mount a stifling presence in Asian waters. Wartime prime minister General Hideki Tōjō catalogued submarine warfare among three critical determinants of Japan's defeat—high praise from someone in a position to know.

And afterward? Ravaged by undersea combat during World War II, Japan built an impressive submarine force of its own to help prosecute the Cold War. Japan Maritime Self-Defense Force (JMSDF) diesel boats turned geography to advantage, lurking in and around the straits that pierce Asia's offshore island chains. Crews monitored and encumbered east-west movement between the China seas and the Western Pacific. Soviet skippers often balked at attempting the passage. The JMSDF, in short, forged itself into a lethal weapon for a cold war beneath the waves.

And so it remains. JMSDF Soryu-class diesel attack boats are the biggest boats of their type, and they're acclaimed among the best—for good reason. Their size lets them carry large amounts of fuel, weaponry and stores, making long patrols feasible. The depths offer a sub its best concealment. Accordingly, Japanese SSKs are outfitted with air-independent propulsion, obviating their need to surface and snorkel frequently. That's an Achilles' heel of older diesel subs. Soryus, then, can remain underwater for long stretches, evading detection from the surface or aloft. And their acoustic properties are excellent while submerged—helping them elude enemy passive sonar. What adversary sonar men can't hear can hurt them.

In short, Soryus are optimized for plying the China seas and Western Pacific. Those are precisely the waters the U.S. Navy, Marine Corps, and Coast Guard singled out as crucial in the 2007 Maritime Strategy, the sea services' most authoritative statement of how they see the strategic environment and intend to manage it. Soryu SSKs are proven platforms manned by experienced mariners who can bequeath their knowledge to their U.S. comrades. That makes these boats a logical common platform around which to build a combined SSK squadron.

Let's evaluate the Soryus' candidacy while remaining mindful that many other capable diesel subs—for instance, the German Type 214—are also on the market and worth considering. In operational terms, what would a U.S.-Japanese force do? Its strategic rationale would be straightforward: it would turn access denial against China, its foremost contemporary practitioner. Reciprocity is a fine thing. Or, if you prefer your strategic wisdom colloquial, paybacks are a b*tch.

In other words, if Beijing wants to deny U.S. forces access to the theater, U.S. and Japanese commanders should reply in kind. They can deploy submarines along the first island chain to fight in concert with surface forces, detachments of missile-armed land troops, and shore-based tactical aircraft. Combined-arms forces could:

- Keep the People's Liberation Army (PLA) from wresting away beachheads in the island chain. Bursting through the island chain would turn Japan's southern flank (and Taiwan's northern flank), compromising Japanese territory while making it far harder to cordon off the China seas. Defending the islands should be Job One for allied forces.

- Expel China's flag from crucial seaways. Plugging, say, Miyako Strait (south of Okinawa) with submarines while erecting overlapping fields of anti-ship-missile fire overhead would give the most determined PLA Navy skipper pause. He would think twice before trying to exit the East China Sea for the Western Pacific (or to return to home waters if caught outside).

- Make transiting north-south along the Asian seaboard perilous in the extreme. SSKs venturing within the island chain could target merchantmen and PLA Navy units with impunity, imposing unbearable costs on Beijing for making trouble.

In short, staging a combined fleet near likely scenes of action would give rise to a kind of mutual assured sea denial. Properly executed, allied anti-access preparations would yield a measure of deterrence vis-á-vis China—enhancing prospects for uneasy peace in the Far East.

But why diesel boats? Isn't the all-nuclear U.S. silent service the world's finest, a silver bullet in the navy's chamber? Yes and no. A U.S. Navy boat remains the odds-on favorite in a duel against any single antagonist. Mass is a severe and worsening problem, however. If the fleet disperses itself all over the map, as global navies are wont to do, it's apt to find itself outmatched at some trouble spot or another. Never mind how capable an individual platform may be. If commanders concentrate assets in one trouble spot, on the other hand, other priorities may go uncovered. Now as ever, quantity has a quality all its own. And quantity is precisely where trouble lies.

The reason for dwindling fleet totals should astound no one. It's dollars and cents. As Cold War-era Los Angeles-class nuclear attack subs (SSNs) retire, they're being replaced not on a one-for-one basis but by fewer, more expensive Virginia-class SSNs. As costs rise and shipbuilding budgets stagnate—if that—downward pressure on numbers mounts inexorably. The fleet is projected to sag from 55 SSNs today to as low as 42 around 2030.

Forty-two sounds like a lot, doesn't it? But naval leaders are forever reminding us that seven-tenths of the earth's surface is covered by water. The seven seas adds up to an awful lot of waterspace for 42 boats to police—especially since a sizable fraction of that tally is in overhaul, routine maintenance, or workups on any given day. Many units, that is, are unavailable for combat duty no matter how sorely they're needed. Shave a third off the raw number of ships and you have a good guesstimate about the number of subs available to some degree or another.

Sure, 60 percent of the SSN contingent now calls the Pacific home. But though the percentage sounds impressive, that's only 33 vessels, a number that could shrink as low as 25 by 2030. And allied fleets? The JMSDF is expanding its own subsurface contingent from 16 to 22 SSKs, mainly by extending the service lives of boats already in the inventory. Thus a combined U.S.-Japanese fleet of 47 subs would be arrayed against some 70 PLA Navy attack boats within the foreseeable future. But even that figure probably exaggerates. It relies on the doubtful assumption that Washington concentrates the entire Pacific Fleet submarine force in the Western Pacific—letting commitments elsewhere go.

That's a 50 percent advantage numerical advantage for China—at a minimum. Again, allied submarines remain superior, boat for boat, but at some point brute numbers begin to tell. So the challenge before Washington is to add capable boats to its fleet on the cheap. (Tokyo could do its part by scrapping its self-imposed cap on defense spending and investing more generously in undersea warfare.) Here the figures are striking. The unit cost for the Soryu is estimated at $500 million, whereas each copy of the Virginia class comes in at a cool $2.8 billion. Do the math. It appears the U.S. Navy could afford five Soryus for the price of one Virginia, with change left over. That's bang for the buck.

Admittedly, the barriers to reentry into conventional submarine warfare would be formidable. For one, the ghost of Hyman Rickover would haunt any such debate. SSKs, unlike SSNs, command little obvious constituency within the submarine force, the navy, or Congress. Overcoming the all-nuclear mystique would demand concerted effort on the part of diesel proponents, perhaps with help from some truly dire budgetary pain. Such pain is more likely than not. In the 2020s, for instance, the navy will commence replacing its Ohio-class ballistic-missile submarines. Top navy leaders have warned that this project alone could drain shipbuilding coffers. Inexpensive non-nuclear alternatives may come to look palatable—if not downright appealing—under such fiscal circumstances.

Next, cultural proclivities aside, the nuclear navy would likely construe any move to acquire diesel boats as a threat to current SSN procurement plans. They might see an SSK program as a substitute for new Virginias, not as a complement to the nuclear-powered fleet. It would look like an attempt by cost-cutters to save money on the sly, at the expense of operational effectiveness. Defense manufacturers—particularly those specializing in naval nuclear propulsion—would add their voices to the din. And the outcry would be universal and twice as loud should Washington contemplate buying foreign—witness the uproar among Australian firms over Canberra's apparent decision to buy Soryus rather than replace its Collins-class SSKs with an indigenous make.

In short, the pushback from guardians of the status quo would be frightful to behold. This is a debate worth having nonetheless. Think about the upsides to diesel subs, even apart from their modest cost:

- If indeed the Australian government proceeds with a purchase of ten Soryu-class boats to replace its underperforming Collins class, the Soryu could form the nucleus of a multinational East Asian submarine force spanning more than just the U.S. Navy and the JMSDF. Other partners could join in. Basing, maintaining, and employing a standardized fleet would be far easier than it is with the usual hodgepodge of ships built by many designers from many countries.

- Multinational detachments could operate not just from Japan or Guam to the north but from the Philippines or Australia to the south. A standing allied presence along the first island chain would constitute a potent deterrent to Chinese mischief. So would an exterior position in Australia. Such a strategic position would grant diesel boats access to the South China Sea at many points along that expanse's permeable rim.

- As World War II and the Cold War proved, proximity to patrol grounds magnifies the operational and strategic efficacy of undersea combat. Short transit times equates to more time on station and less wear-and-tear on people and hardware. Mounting patrols from homeports in the region thus boosts the number of hulls ready for sea when the balloon goes up.

- Embracing a time-tested common platform would ease the interoperability problems that plague multinational ventures. Dissimilar gadgetry, tactics, techniques, and procedures, and national and service cultures throw sand in the gears of coalition operations, generating the "friction" that Carl von Clausewitz bewailed two centuries ago. The lubricant Clausewitz recommended was combat experience. Yes; and combat experience lubricates best when the warriors all carry the same arms. Never underestimate the power of standardized equipment—especially when a corps of experts, namely JMSDF submariners, already exists that can pass down knowledge and expertise to newcomers. U.S. submariners could ascend the diesel-boat learning curve swiftly, making themselves proficient in this new, old technology.

- And lastly, a return to conventionally powered subs would confer side benefits within the U.S. Navy. Since the inception of atomic power, with its technical rigor and time-consuming training, it has become rare indeed for surface-ship sailors to cross over to serve in submarines, or vice versa. It's almost unheard of to do what, say, a guy named Chester Nimitz did: start off life as a submariner before going on to serve in cruisers. Reintroducing conventional subs could reintroduce the professional mobility of times gone by. Each community would profit from knowing the other's operating element firsthand. The navy as a whole would profit from collapsing some of the stovepipes—a.k.a. "cylinders of excellence"—that separate communities from one another to such baneful effect.

So let's open a new conversation within the naval community. And let's not accept "because...Rickover!!!" or kindred excuses for staying with current methods and hardware. If not diesel submarines, why not?

James Holmes is Professor of Strategy at the U.S. Naval War College and coauthor of Red Star over the Pacific. The views voiced here are his alone.

Critically missing in this 3rd world retro WWII technology “what if” discussion is the fact that diesel boats are noisy. Noise= death. So it wouldn’t matter how many could be deployed, they’d provide a target rich environment for the silent, fast killers of ASW and AS killer subs (the, uh, nuclear ones).

Now, there are some extremely quiet new electric subs that are providing a bit of a scare. But the people who know about them, can’t talk freely about them. And they are being acted upon.

Incidentally, the system that makes fresh water onboard- using a catalytic reaction of sea water— that has a lot of danger in its design and technology, have heard from many inside.

I'm not a naval tactician so you veterans can correct me, but with planes and satellite surveillance looking for subs, it's not going to be as easy to hide them as in WWII.

Also it wouldn't be really hard to not develop a pattern of snorkeling or refueling making them very predictable and vulnerable targets. Nuclear boats have the advantage of disappearing when the submerge not surfacing till they return.

Question for our active/armchair naval buffs:

Having the diesel running is to be a sitting duck. The article doesn't talk about it, but wouldn't the noise of the diesel hamper the subs passive sonar and make them deaf/blind sitting duck? Helicopters use active noise suppression are there similar systems that function that could cancel the noise of the engines.

Observations on U.S. submarines in WW2.
1. Outside of teaching submariners the basics, most but not all American subs went to the Pacific.
2. Torpedoes in the submarine service, Mk 14, and surface fleet, Mk 15, were equally bad. The multiple deficiencies of faulty magnetic exploders, faulty depth keeping mechanism, and faulty contact exploders weren't solved until mid-1943. Then the Japanese really stated to lose ships.
3. Of the total numbers of merchant vessels and warships afloat on 7 December 1941, at the time of surrender on 2 September 1945, Japan had lost 1/3 of its warships and 2/3 of its merchant marine.
4. Most of the pre-war O, R, and S-class boats were used for training. The pre-war built boats — a few S-class, Barracuda-class, Argonaut and Narwhal-class, Dolphin and Cachalot-classes, P-class, Salmon-Sargo class, Tambor-Gar class, Gato-class, Balao-class, and Tench-class — were boats that bore most of the Pacific fighting.
5. A total of 52 submarines were lost, with 374 officers and 3,131 enlisted men. These personnel losses represented 16% of the officer and 13% of the enlisted operational personnel. Of the 52 losses, two submarines, Dorado and R-12, were lost in the Atlantic, S-26 was sunk in a collision off Panama and S-28 was an operational loss in training at Pearl Harbor. The remaining 48 were lost either directly or indirectly as a result of enemy action, or due to stranding on reefs during combat operations.S-39, S-36, S-27 and Darter were lost as a result of such strandings. In all of these events, all personnel were rescued.
6. U.S. World War II Submarine Operational Summary:
•Maximum number of U. S. Submarines in the Fleet = 288
•Number that made war patrols = 263
•Number of War Patrols made by Submarines in the Pacific = 1,474
•Number of days at sea by those Submarines = 70,838
•Number of Japanese ships attacked by submarines = 4,112
•Total number of Japanese ships sunk by submarines = 1,392
•Average number of merchant ships sunk/war patrol = 0.80
•Average number of naval vessels sunk/war patrol = 0.145
•Average number of all types of ships sunk/war patrol = 0.945
•Number of airmen rescued by Submarines = 504 by 86 Submarines
•Number of Submarines lost on war patrol = 41, or 1 out of every 6.41 submarines = 15.59%
•Number lost due all causes = 52 out of the 288 in the Fleet, or 1 out of every 5.54 Submarines = 18.06%
•Number of U.S. Submarine Commanding Officers = 465
•Duration of the war = 1,347 days

The latest diesel-electric, air independent propulsion subs are very hard to find and kill. One of the very best designs is the German U-212A design. The German Type 212A-class, also Italian Todaro-class, is a highly advanced design of non-nuclear submarine developed by Howaldtswerke-Deutsche Werft AG (HDW) for the German and Italian Navy. It features diesel propulsion and an additional air-independent propulsion (AIP) system using Siemens polymer electrolyte membrane (PEM) hydrogen fuel cells. The submarine can operate at high speed on diesel power or switch to the AIP system for silent slow cruising, staying submerged for up to three weeks without surfacing and with no exhaust heat. The system is also said to be vibration-free, extremely quiet and virtually undetectable.

Type 212A is the first of the only two fuel cell propulsion system equipped submarines ready for series production in 2007, the other being the Project 677 Lada-class submarine designed by the Russian's Rubin Design Bureau.

Your comment is on target— noise is the problem. The article is not well informed, or informed for the “last” war, and for lesser countries than the US. IMHO, it presupposes “cheap” alternatives that will just not do in a major conflict, which it would be with the USA.

Commented on the newer long battery super quiet electric boats— they are pretty sophisticated and scary.

Family member was lifetime submariner— pre WWII to the Nautilus and then reservist from then on until too old really. Knew everybody including the famous ones (and the nut jobs, LOL).

“... diesel boats are noisy. Noise= death. ...

Incidentally, the system that makes fresh water onboard- using a catalytic reaction of sea water— that has a lot of danger in its design and technology, have heard from many inside.”

Most of the people who might know (and deign to talk) describe hybrid submarine power systems (diesel/electric) as quieter than nuclear power systems.

Missing from this thread so far is the truism that detection and masking technologies and tactics are not static. Professor Holmes - like most sea power apologists - assumes that remote (above surface, airborne or orbital) detection of subs will never be possible. Don’t count on it.

Only nuclear power can provide the electricity needed to run the catalytic cracking devices and desalinators that supply air and water for the sub crew. This still guarantees that nuclear boats will continue possess range and endurance no hybrid power system can yet match. If increased cost is the price of outlasting an enemy, we must recall that success might be priceless.

The fleet really threw a punch once the Navy got torpedoes that actually blew stuff up. The early torpedoes were terrible.

If it weren't for the war, people would have been gone to prison for what happened as a result of the shoddy work, pathetic bureaucracy and defective torpedoes. TWO YEARS. Imagine if any other service had defective shells/bullets with the same failure rate for the same term in the rest of the war...

http://www.defensemedianetwork.com/stories/torpedo-scandal-rear-adm-charles-lockwood-the-mark-14-and-the-bureau-of-ordnance/

“The Radar equipped B24’s helped a little bit.”

By the time Allied war planners noticed that Imperial Japan’s war effort was critically dependent on merchant vessel traffic (from China/Korea, mainland Asia, East Indies etc; and in Home Island coastal waters), USN’s submarine force had already caused a major impact, and by war’s end accounted for the great majority of Japanese merchant ships destroyed.

But anti-ship campaigns conducted by air took their toll.

Night attacks by USAAF bombers (many by B-24s, as noted) and USN patrol aircraft (many by PBY “Black Cat” units) were by far the most daring, and likely the most unnerving, from an aircrew standpoint. But most of these attacks were carried out far away from Home Island waters, simply because no Allied aircraft had the range to carry the fight to the enemy’s front yard.

Quite late in the war, it was decided that USAAF’s B-29s (the sole Allied aircraft with the range and payload to get the job done) would haul naval mines from the Marianas to lay minefields in Home Island waters, to interdict local merchant vessel traffic.

In terms of effort applied versus result, this final campaign was the most effective, cutting total transported tonnage by some 90 percent, eventually accounting for some eight percent of the Japanese merchant vessel tonnage lost.

See the US Strategic Bombing Survey for additional results.

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