Chief of Naval Operations Admiral J. M. Boorda has revealed that the Russian Navy has several submarines at sea that are quieter than the latest U.S. submarines, the improved Los Angeles (SSN-688) class.1 His statement reveals that the United States has lost what had long been touted as the primary—and most important—U.S. advantage over Soviet- Russian undersea craft.
These very quiet Russian submarines are the improved Akula (Project 971) class.2 The Akula is an advanced, nuclear-pro- pelled attack submarine (SSN) that first went to sea in 1985. About six units were built before the Russians shifted to the improved or Akula II design, the first of which was completed about 1990. Six of the improved submarines are believed to be at sea, with another, the Viper, now on trials. The Viper may be the first of the lengthened—and possibly still quieter—Akula II submarines.
The U.S. Navy, presumably using the seafloor sound surveillance system (SOSUS) as well as trailing operations, determined the noise levels of the improved Akula. Details of which specific kinds of sounds are quieter for the improved Akula than for the “688-1” have not been revealed. A submarine has four noise sources:
- Machinery: main propulsion and auxiliary, especially pumps in nuclear propulsion plants that circulate coolant fluids
- Propeller: including blade-induced vibrations and the breaking up of bubbles caused by propeller rotation
- Hydrodynamic: the flow of water around the submarine’s hull, sail, and control surfaces as the submarine moves through the water
- Transitory: pulse-like noises created by the movement of torpedo tube doors or shutters, control surfaces, and other submarine activities
Initially, U.S. as well as Soviet nuclear-propelled submarines were noisy. Indeed, first generation U.S. SSNs often could not evade U.S. antisubmarine forces when they attempted to use their speed to escape because of their high noise levels. But in the mid-1950s, as SOSUS was providing long-range detection of U.S. submarines—diesel-electric as well as the first nuclear boats—the decision was made to quiet U.S. nuclear submarines. The first “quiet” SSN was the Thresher (SSN-593), completed in 1961. Quieting was a major challenge to designers and engineers; Admiral H. G. Rickover, long-time director of nuclear propulsion development, once said, “Making them quieter is a bigger job than nuclear power.”
The Thresher proved to be highly effective; not only was she more difficult to detect, but the quieting made her advanced AN/BQQ-2 sonar system more effective. Although quieting was expensive and required considerable space—making the Thresher larger and hence slower than the previous Skipjack (SSN-585) class—it quickly became the principal criteria for U.S. submarine design. Vice Admiral N. R. Thunman, then-Deputy Chief of Naval Operations (Submarine Warfare), told Congress:
... it is essential that we retain the acoustic advantage. If the combination of our sonar capability and sound quieting is such that we are better than the Soviet sonar capability and sound quieting, we will detect him before he detects us.3
Throughout the 1960s and 1970s and into the 1980s, the U.S. acoustic advantage was touted as making U.S. submarines superior to Soviet undersea craft, although the Soviets surpassed the U.S. Navy in nuclear submarine numbers, speed, operating depth, and weapons payload. Indeed, some U.S. submariners declared that the Soviets could “never” make a quiet submarine because of their adherence to double-hull designs and the resonant emission of the outer hull under the effect of water flow.4 When the Soviets introduced anechoic coatings for undersea craft in the mid-1960s, this, too, was denigrated by U.S. submariners as being ineffective.
By the early 1980s, however, the leadership of the U.S. submarine force began voicing some concern about the steady improvements in Soviet submarine quieting, although they claimed that the gap between the two navies was closing slowly. Admiral James D. Watkins, the first nuclear submariner to serve as Chief Of Naval Operations, observed; “When my first command, USS Snook [SSN-592], was launched , we were infinitely ahead of the Soviets in nuclear submarine technology. Later, about , we were about ten years ahead of them. Today  we are only about five-to-eight years ahead of them and they are still in relentless pursuit.”5
Still, the U.S. Navy was surprised in the early 1980s as the third generation of Soviet submarines began going to sea. U.S. SSNs trailing those undersea craft and SOSUS detections revealed noise levels much lower than predicted.6 Rear Admiral Thomas A. Brooks, then-Director of Naval Intelligence, noted that “[the] Akula produces noise levels that the U.S. had not projected the Soviets to attain until the early 1990s.”7 The gap had almost closed.
Concern about Soviet advances in quieting led a senior U.S. submarine designer to declare, “There will come a time in the not too distant future when Soviet submarine silencing will have improved to the extent that detection by passive sonar is possible only at short ranges, if at all.”8 This view subsequently was confirmed by a top-level study panel sponsored by the U.S. House of Representatives, which concluded that because of Soviet submarine developments, “the [U.S.) Navy must, in effect, ‘start over’ in its approach to ASW.”9
Addressing specific Soviet submarine developments, the report continued:
It is true that the Soviets’ submarine [research and development] program is extremely ambitious, [it] seems to overlook no promising technologies, and—in that it dates back many years—is no flash in the pan. ... the Soviets may well be ahead of us in certain technologies such as titanium structures and control of the hydrodynamic flow around a submarine.
But far more important is the improvement that the Soviets have made in submarine quieting. The problem is not that Soviet submarines are now quieter than ours; they are not. But after decades of building comparatively noisy submarines, the Soviets have now begun to build submarines that are quiet enough to present for us a major technological challenge with profound national security implications.10
A decade later—in 1994—the improved Akula SSNs were determined to be quieter than the improved Los Angeles class. On 21 December 1993, the keel was laid down for the Severodvinsk (Project 885), the fourth-generation Soviet-Russian SSN. U.S. naval intelligence contends that the Severodvinsk will be only slightly quieter than the improved Akula (see Figure 1). The Russian approach to submarine quieting has been multi-facilitated while maintaining high speeds, deep operating depths, and the double-hull configuration.
The Soviet emphasis on quieting seems to have begun in the mid-1970s. Russian submarine designers have told the author that their own tracking of their submarines with seafloor acoustic systems indicated the high noise levels of their nuclear submarines." Western sources—and some Russians—say that the emphasis on quieting was the result of Chief Warrant Officer John A. Walker, who betrayed U.S. secrets to the Soviets beginning in 1968.12
Significantly, the displacement (volume) growth of Soviet submarines has not been proportional to quieting. The U.S. Navy has used an add-on method of quieting, wherein each submarine design followed the basic Skipjack configuration (i.e., Albacore [AGSS-569] hull and S5W reactor plant) with changes made to counter specific noise sources. The Soviets appear to have used more of a systems approach, with successive submarine design having an overall, integrated quieting effort. This has been possible, in large part, because of the high degree of independence of the three Soviet submarine design bureaus—Rubin and Malachite in Leningrad/St. Petersburg and Lazarite in Gor’kiy/Nizhny Novgorod—and related research institutes." In contrast, U.S. submarine research and development and design efforts are closely and narrowly controlled by the nuclear propulsion directorate of the Naval Sea Systems Command.
Early on, the Soviets worked at reducing hydrodynamic flow noises. This can be seen by the blending of the sail into the hull, flow-control strakes, covers over limber holes, and other features (some of which are now incorporated into the U.S. Seawolf [SSN-21]). Propulsion quieting includes rafting of turbines (introduced in the Victor SSN), advanced propeller designs, and other features also employed in U.S. submarines. Building on German development of the Alberich anechoic coatings in World War II, the Soviets have developed what appear to be multipurpose coatings, which reduce the effectiveness of allied homing torpedoes by absorbing their active sonar pulses, but also help to mask internal noises. Further, the Russians are reported to employ up to three separate coatings in their double-hull submarines—one coating on the outer hull and coatings on both surfaces of the inner hull, further masking internal noises. (The coatings may also affect water flow over the hull, reducing flow noises, as well as cutting drag.)
Other features are also employed by the Russians to reduce submarine noises, including a unique scheme of active noise cancellation. This method of quieting measures certain noise frequencies and produces—in real time—a canceling tone. There also are indications that the Russians have evaluated injecting polymer substances into a turbulent boundary layer around submarines to reduce drag and possibly to reduce flow noises. This scheme would be particularly important for increasing “quiet speed,” the speed at which a submarine can still use its own passive sonar.
The leadership of the U.S. nuclear submarine community contends that the next U.S. submarine, the Seawolf, will be the world’s quietest submarine when she goes to sea in 1996. Quieting was the highest priority in her design.
A vital question is how quiet the Severodvinsk will be. The U.S. Navy’s intelligence estimate—driven in part by analysis dictated by the nuclear submarine community—indicates that the Severodvinsk will have almost the same noise levels as the improved Akula (see Figure 1). This has become an important fact as the follow-on to the Seawolf program, the New Attack Submarine (NSSN), will have the same level of quieting as the Seawolf; most if not all other NSSN characteristics (speed, weapons, etc.) will be inferior.
Looking back at the Soviet-Russian “surprises” in submarine quieting, one must be apprehensive of U.S. predictions in this area. Why assume that the curve of the Russian broad-band quieting efforts between the improved Victor III submarine and the improved Akula will not be continued? If it were, the Severodvinsk would be as quiet—possibly quieter—than the Seawolf and NSSN.
In general, U.S. predictions are based on characteristics of older Russian submarines as they come out of overhauls, often revealing lower noise levels. There are other sources—both open and clandestine—that shed light on future Russian submarine developments. But if the past is any guide, and considering impressions garnered from discussions with senior officials at the Rubin and Malachite design bureaus, it is more likely that the Severodvinsk will be significantly quieter than the improved Akula—and quieter than the Seawolf, which was designed several years before the Severodvinsk.
There is little reason to believe that the Russian Navy will not maintain its new-found leadership in submarine quieting. But quieting is not a zero-sum game. The United States has two related advantages for at least the next few years: the skill and training of sonar operators, and computer capability related to acoustic data processing. However, neither of these advantages can be assured on a long-term basis.
The current political and economic conditions in Russia mitigate against an effective submarine program. The Severodvinsk is known to be significantly behind schedule, and the fifth-generation Russian SSN, whose design is already under way, is far from being funded. Still, if quieting is the key to U.S. nuclear submarine effectiveness—as long touted by the U.S. submarine community—there are storm waters ahead. There is a window °f opportunity over the next few years, as Russian submarine development, despite its technological progress, is in disarray because of the general situation of the Russian nation and armed forces. Perhaps the U.S. Navy can take advantage of this window to (1) objectively evaluate the U.S. submarine situation and the relative importance of various submarine characteristics, including quieting, and (2) pursue innovative approaches to providing submarine superiority.
The situation demands careful action. As Admiral Boorda has told Congress: “This is the first time since we put Nautilus to sea that [the Russians] have had submarines at sea quieter than ours. As you know, quieting is everything in submarine warfare.”14
1 Adm. J. M. Boorda, USN, meeting with Naval & Maritime Correspondents Circle, Washington, DC, 27 February 1995.
2 The Akula class was designed by the St. Petersburg Marine Engineering Bureau “Malachite.” The bureau has designed most Soviet-Russian SSNs as well as midget submarines and participated in early ballistic missile submarine work.
3 VAdm. N. R. Thunman, USN, testimony before the Committee on Armed Services, House of Representatives, 11 March 1982.
4 The U.S. Navy gave up double-hull construction with the Thresher class because of the large diameter required for rafting of machinery to reduce propulsion noises.
5 Adm. Watkins, USN, speech at change of command, Commander, Submarine Force, Atlantic Fleet, Norfolk, VA, 27 June 1983.
6 The Soviet third-generation submarine classes are:
NATO Code Name
7 RAdm. Brooks, USN, testimony before the Seapower, Strategic, and Critical Materials Subcommittee of the House Armed Services Committee 22 February 1989.
8 Capt. Harry A. Jackson, USN (Ret.), et al., “ASW: Revolution or Evolution,” U.S. Naval Institute Proceedings, September 1986, p. 68. Also see Lt. David I. Nylen, USN, “Melee Warfare,” U.S. Naval Institute Proceedings, October 1978, pp. 56-64.
9 Report of the Advisory Panel on Submarine and Antisubmarine Warfare to the Subcommittees on Research and Development, and Seapower and Strategic and Critical Materials, House Armed Services Committee, 30 January 1989, p. 2.
10 Ibid., appendix, p. 1.
11 Discussions with senior engineers, Central Design Bureau "Rubin,” St. Petersburg, May and October 1994.
12 Walker, a communications specialist, had served in two strategic missile submarines and subsequently was assigned as a communications watch officer at the headquarters of the Atlantic Fleet submarine force.
13 Lazarite no longer designs combat submarines.
14 Adm. J. M. Boorda, USN, testimony before National Security Committee, House of Representatives, 22 February 1995.