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Increasing the Mission Capability of the Attack Submarine Force March 2002

To reduce the cost of meeting its force goals for attack submarines, the Navy could increase the number of mission days that the current force provides. This chapter looks at several ways to do that, all of which expand on ideas that the Navy intends to implement or that have been discussed in policy debates. The first option would convert four retiring Trident submarines to perform missions identified in the 1999 study published by the Chairman of the Joint Chiefs of Staff. The Congress appropriated $430 million this year to begin the process of converting those submarines. The second option would use more than one crew to operate some Virginia class attack submarines. The third option would base up to 11 SSNs in Guam, building on the Navy's plan to transfer three submarines there from the United States.

To evaluate those options, the Congressional Budget Office examined whether they could provide enough extra mission days to meet the force goals laid out in the CJCS study. CBO also calculated the options' cost per additional mission day (above the level provided by the Navy's planned force of 55 SSNs) to compare their cost-effectiveness.⁽¹⁾ Each option assumes that the Navy will base three SSNs in Guam indefinitely. In addition, although all of the options assume that the Navy will implement its long-term procurement plan, CBO examined how the options would affect equivalent force levels if the Navy was unable to increase submarine construction from the current rate of one per year.
 

Option I: Convert Four Trident Submarines to SSGNs

In this approach, the Navy would maintain a force of 55 attack submarines. In addition, as it plans to do, the Navy would convert four Trident ballistic missile submarines scheduled for retirement in 2003 or 2004 to a guided-missile, or SSGN, configuration so they could perform nonnuclear missions. Those SSGNs would employ a system of dual crews similar to the one that Trident submarines use now. As a result, four SSGNs could provide about the same number of mission days as 12 attack submarines. That increase would boost the mission capability of the attack submarine force substantially through about 2025. After that, however, the equivalent force level would fall below 68 as the SSGNs were retired.

The SSGN Concept

The Navy currently operates 18 Ohio class submarines that carry Trident strategic ballistic missiles. Ten of those submarines have D5 missiles; the other eight are fitted with older C4 missiles, which are less accurate and have a shorter range than the D5. The Navy plans to upgrade four of the submarines armed with C4s over the next several years so they can carry D5 missiles. The other four C4 submarines had been slated for retirement but will now be turned into SSGNs instead.

Adapting a Trident submarine for cruise missiles involves altering 22 of its 24 missile tubes to carry seven conventional missiles each, for a total of 154 missiles per submarine. Those weapons will give each SSGN about the same land-attack capability as a group of three or four surface combat ships. In addition to that capability, the SSGNs will have electronic-warfare, intelligence-collection, communications, navigation, and sonar equipment comparable to that of the new Virginia class attack submarine. Further, the space freed up by the two unused missile tubes will be converted to launching areas or equipment storage for special-operations forces.

What Missions Would SSGNs Perform?

The Navy has provided conflicting information to CBO about the missions that SSGNs could perform. One source suggests that, at a minimum, they could conduct covert precision strikes with cruise missiles and clandestine operations with special forces. Other missions would ultimately depend on the equipment installed, but according to the Navy, "it is foreseen that the SSGN would be capable of most of the missions of current SSNs, to include undersea warfare (with limited torpedo room capacity), sea control, intelligence, surveillance and reconnaissance, offensive mining, and Naval forward presence."⁽²⁾ SSGNs could also be useful as platforms for demonstrating new technologies in undersea warfare. However, they would probably not be as effective as SSNs in helping aircraft carrier battle groups train, operating under ice, or conducting antisubmarine warfare exercises with other navies.

Other data provided by the Navy suggest that the missions an SSGN could perform, at least with respect to those identified in the CJCS study, would be limited. In constructing this option, CBO relied on that more conservative view.

Most of the discussion of SSGNs, both inside and outside the Navy, focuses on having those submarines available to perform strike (land-attack) or special-operations missions. But strike was not mentioned in the CJCS study as a required mission for attack submarines, nor were some of the special operations that the Navy has in mind for SSGNs. Thus, if SSGNs were used for those purposes, they would probably not be available most of the time to perform missions identified in the CJCS study. Ultimately, how to use SSGNs is a choice for policymakers.

For the purposes of this option, CBO chose to use the SSGNs to conduct missions identified in the CJCS study. In a document provided to CBO, the Navy stated that SSGNs could fully perform 12 percent of the mission days in the CJCS study and partially perform another 10 percent. For analytic purposes, CBO assumed that SSGNs could carry out 17 percent of the CJCS mission days (halving the 10 percent to 5 percent and adding it to the 12 percent).

Mission Days and Force Levels

In a 1999 report to the Congress, the Department of Defense (DoD) anticipated that with a force of four SSGNs, two could remain forward deployed in different theaters at all times.⁽³⁾ Achieving that high level of forward presence would require retaining the blue/ gold crew model used for operating Trident submarines, albeit with some modifications. (That model is described in detail in Option II.) Each SSGN would most likely employ a 224-day operating cycle in which the submarine would be deployed for 174 days followed by a 50-day period in port. If the blue crew took the submarine on patrol, the gold crew would fly out and change places with the blue crew in the middle of the patrol (see Figure 7).⁽⁴⁾ On every third patrol, the SSGN would undergo a process to certify that it was qualified to perform special operations.
 

Figure 7. Deployment Cycle for an SSGN Assigned to the Atlantic Fleet and Based in King's Bay, Georgia

SOURCE: Congressional Budget Office based on information from Department of Defense, Office of the Under Secretary of Defense for Acquisition and Technology, Analysis of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered Guided-Missile Submarines (SSGNs), June 1999.

NOTES: Shaded areas in the top line represent short periods of transit, in-theater crew exchanges, or maintenance.

SSGN = nuclear-powered guided-missile submarine; Centcom = Central Command; Eucom = European Command; SOF Cert. = special-operations forces certification, which would occur every third cycle.

CBO calculated that an SSGN could provide up to 142 mission days per year. That figure originates from information in DoD's 1999 report to the Congress, which stated that in the course of three 224-day operating cycles (672 days), an SSGN would spend 150 days in its home port being refitted, 90 days going to and from a theater of operations, 42 days undergoing crew exchanges and some maintenance in-theater, and 20 days for the special-operations certification. The report was trying to quantify presence (simply being in the theater of operations), however, so it did not include time spent moving from one location to another within a theater to perform different missions. CBO added 72 days for in-theater transit to that list on the basis of historical averages for attack submarines.⁽⁵⁾ Thus, out of 672 days, an SSGN would devote 298 days to missions--the equivalent of 162 mission days per year.

That number, however, does not take into account the time a submarine spends in long-term, shipyard-level maintenance. A Trident ballistic missile submarine that has been refueled is expected to spend about 5 percent of its remaining service life in long-term maintenance, compared with 12 percent for an attack submarine. But because an SSGN would be used more like an attack submarine than a ballistic missile submarine, CBO chose the 12 percent figure. Subtracting that time for maintenance reduces the average annual mission days for an SSGN to 142--equal to four attack submarines based in the United States.

As noted above, though, CBO assumes that SSGNs will be limited in the types of missions in the CJCS study that they can perform. In accordance with data given to CBO, this option assumes that each SSGN will provide about the same number of mission days as three attack submarines rather than four. The rest of that time could be used to conduct missions that are not identified in the CJCS study or (as discussed in the next section) to train at sea. Nevertheless, the four SSGNs in this option would add substantially to the mission capability of the attack submarine fleet until about 2026, when the last of them would reach the end of its service life (see Figure 8). Replacing those SSGNs with new submarines would probably not be cost-effective unless the Navy built a new class of ballistic missile submarines.⁽⁶⁾
 

Figure 8. Effect on Equivalent Force Levels of Converting Four Trident Submarines to Perform Conventional Missions

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that each SSGN would be equivalent to about three SSNs with respect to mission days provided. Actual force levels would be lower than the equivalent force levels shown here.

The Navy's plan assumes an average production rate of 2.2 subs a year between 2002 and 2020, compared with the current rate of one per year. After 2020, it assumes a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76 submarines.

SSN = nuclear-powered attack submarine; SSGN = nuclear-powered guided-missile submarine.

a. Includes three SSNs based in Guam, each one of which is equivalent to about three SSNs based in the United States with respect to mission days provided.

Maintenance and Training

In the Navy's plans (and in this option), most maintenance on an SSGN would take place at the submarine's home port. The Navy's notional deployment cycle for SSGNs provides for some in-theater maintenance, perhaps with the support of a tender. But that in-theater maintenance period (14 days) is shorter than the current maintenance period for a Trident submarine (38 days, all of them spent at the home port). Therefore, to compensate, the SSGN would also spend 50 days undergoing maintenance at its home port, including maintenance on its Tomahawk missile systems.

In terms of crew training, SSGNs would resemble Trident submarines more than attack submarines. Unlike attack submarines, they would not perform at-sea training prior to deployment. The crew that did not deploy would conduct its training in the submarine's home port, similar to the way that the crew of a Trident sub performs its training, but adjusted for the difference in missions. That training would occur primarily at the on-shore training facilities in Kings Bay, Georgia, or Bangor, Washington. According to the Navy, "the plan is to use the existing Trident Training Facilities (TTFs) as much as practical and the baseline plan includes installing training facilities associated with the Tomahawk systems at the TTFs, and modifying the ship control trainers to include SOF [special-operations forces] operations simulations."⁽⁷⁾

That plan is consistent with the information that DoD provided to the Congress in its 1999 reports on converting Trident submarines. Indeed, to achieve the level of presence envisioned in those reports--two SSGNs forward deployed at any time--the Navy would have to use the Trident subs' existing training facilities and concepts, which do not provide for at-sea training.

In reality, the Navy cannot be certain yet whether SSGN crews will need at-sea training and certifications to perform their required missions (whatever those might be). The Navy is trying to determine that, although it may have to wait for actual experience with SSGNs to know for sure.

If it turns out that SSGNs cannot perform their missions without at-sea training, then the conversion concept will have been oversold and probably will not be able to provide the desired level of overseas presence. Conversely, if SSGNs can carry out their missions without at-sea training, then it would validate the concept of having a dual-crewed submarine perform many of the missions of an attack submarine (see Option II).

For the purposes of this option, an SSGN could spend more than 35 days a year conducting at-sea training and certifications without undercutting its effectiveness in performing the missions identified in the CJCS study.

Other Issues

Some Navy officials are concerned that four SSGNs (with only two operational at any given time) would not be able to provide the same geographic coverage as 12 attack submarines. If some of the missions that SSGNs can perform needed to be done simultaneously, a few might go unfulfilled. There is no way to know for certain whether that will be the case 15 or 25 years from now, but it does represent a measure of additional risk in this option.

Although present, that risk is probably overstated. The three attack submarines that each SSGN would nominally replace would not have been deployed at the same time but at different times, to provide more continuous coverage. One SSGN, with its larger number of mission days, would simply provide the same level of coverage.

What is not overstated about this option is the potential loss of flexibility. If a crisis or war occurred and most or all of the Navy's submarines were deployed, having 12 attack submarines would give military leaders more flexibility to meet the emergency than having four SSGNs would. Nevertheless, because this option envisions maintaining a force of 55 attack submarines, the four SSGNs would represent a force in addition to what the CJCS study says the United States needs for wartime missions.

Overall Cost-Effectiveness

Option I would be relatively cost-effective through 2026, CBO estimates. It would require some significant investment--a total of approximately $4 billion to refuel, convert, and arm the SSGNs.⁽⁸⁾ Average annual costs through 2007 would be $610 million more per year than in the Navy's plan (see Table 3).⁽⁹⁾ However, the cost per mission day of the total force of attack submarines and SSGNs would be $2.2 million, substantially less than if the Navy built an equivalent number of attack submarines (see Table 4). That cost-effectiveness would not change even if the remaining service life of the SSGNs was only 15 years rather than the 20 years that the Navy assumes.
 

Option II: Use More Than One Crew on Some Virginia Class Submarines

This option also envisions a fleet of 55 attack submarines, but some of them would have either two alternating crews (dual crewing), similar to Trident submarines, or three crews rotating between two submarines (multiple crewing). In either case, the force of 55 attack submarines would provide about the same number of mission days as a force built to meet the CJCS goals of 68 SSNs by 2015 and 76 by 2025--at much lower cost.

Current Operating Cycles and Crewing Concepts

Understanding the changes that Option II would make requires knowing some basic information about the Navy's current operating cycles and crewing concepts for submarines. The Navy operates one class of ship with dual crews: the Ohio class submarines that carry Trident missiles. The approach used for those subs is very different from the single-crew operating concept used for attack submarines. Navy officials have expressed a number of concerns about applying the Trident dual-crew model to attack submarines.

The Blue/Gold Crewing Concept for Trident Submarines. The Navy's current model for using more than one crew to operate a ship is the blue crew/gold crew concept used with Trident submarines.⁽¹⁰⁾ Under that operational concept, two crews (named blue and gold) are assigned to each Trident sub. The blue crew takes the submarine on a 74-day patrol, after which it brings the sub back to port and both crews conduct 38 days of maintenance.⁽¹¹⁾ The gold crew then takes the submarine on another 74-day patrol and returns home, at which point both crews again carry out 38 days of maintenance.

That cycle repeats throughout the 42-year service life of a Trident submarine, broken only for longer periods of maintenance. For example, after 14 years, the sub requires an extended refit period in which it goes into dry dock for four months. At about the 21-year mark, the submarine returns to dry dock for two years, during which its reactor core is replaced (refueling the submarine) and additional long-term maintenance is performed. Another extended overhaul period occurs at around the 33-year mark.

With that cycle, the operating tempo of a Trident submarine (the amount of time, on average, that it spends under way in a year) is 65 percent, whereas the personnel tempo (the amount of time, on average, that a sailor spends at sea in a year) is only about 40 percent. Consequently, a Trident submarine is at sea for the majority of its service life.

Supporting that operating concept required a unique effort in submarine design and precise procedures for maintenance and training. First, the Ohio class submarine was designed and engineered to be operated in that manner. Specific features were incorporated in the sub to accommodate faster maintenance, such as an extra-large hatch--called a logistics escape trunk--and removable decks to facilitate the replacement of large pieces of equipment. (Removing large items from a Los Angeles class submarine, by contrast, might require dismantling them onboard the sub, which takes time, or cutting a hole in the hull to remove them.)

Second, the Navy instituted the Trident Planned Equipment Replacement Program for conducting periodic, large-scale equipment changes to ensure that Trident submarines operate with "like-new" equipment during each deployment. Rather than wait for equipment to fail and be replaced as needed, the Navy replaces equipment on Trident submarines according to a regular schedule, whether they need it or not. The maintenance facilities at the Trident submarine bases in Kings Bay, Georgia, and Bangor, Washington, include large dry docks, rail-mobile pier-side cranes to quickly remove or insert large pieces of equipment in the submarines, and advanced machine shops. In addition, those maintenance facilities are given enough resources to ensure a readily available supply of parts that a Trident submarine might need. Consequently, CBO estimates, the annual operating costs for a Trident submarine are about twice those for an attack submarine.

The Operating Cycle of an Attack Submarine. Notionally, the full operating cycle of an SSN is 24 months. The first 18 months make up the interdeployment training cycle (IDTC), followed by a six-month deployment (see Figure 9). In the past, the Navy sent some attack submarines on shorter periods of deployment. But given the post-Cold War reduction in the force, all SSN deployments now last for six months in order to make more efficient use of the time a submarine can spend at sea.⁽¹²⁾
 

Figure 9. Current Notional Deployment Cycle for an Attack Submarine

SOURCE: Congressional Budget Office based on information from the Navy.

During the IDTC, the submarine normally operates at sea for a limited amount of time--no more than 28 days per quarter. During the first year of that 18-month period, the crew periodically takes the submarine to sea for activities such as drills, sound trials, tactical development exercises, support of other submarines preparing to go on deployment, and port calls to U.S. cities. (The submarine might also give underway demonstrations to officials and visitors during those activities.) In the last six months of the IDTC, the submarine conducts what is called pre-overseas movement as the crew prepares to go on its next deployment. The crew must spend between 30 and 58 days at sea to pass its predeployment evaluations and certifications.

The crew also performs maintenance and upkeep on its submarine during the IDTC, especially during the pre-overseas-movement period. The amount of time devoted to that activity is usually no more than 35 days per quarter. Moreover, about 28 days of maintenance are supposed to be performed during deployment. That results in a ratio of maintenance time to at-sea time of 0.87 to 1 (excluding shipyard-level work).

Over the course of its notional 33-year service life, an attack submarine will go through 14 deployment cycles. In between deployments, it will undergo several major maintenance periods. They include stints as short as two months (called selected restricted availabilities) for work at a shipyard. During those periods, the submarine, with some effort, could be sent to sea again in a fairly short time. At approximately the 12-year point, the submarine will undergo a 12-month modernization period in which major repairs and upgrades are performed at a shipyard. At about the 23-year point, it will return for a longer period of maintenance and improvement called an engineering overhaul. During neither of those more-extensive maintenance periods could the submarine be recalled to duty quickly.

That operating and maintenance cycle means that an SSN will spend about four years--or 12 percent--of its service life in long-term maintenance. It will spend about 37 percent of its time at sea, including training near the submarine's home port as well as deployment. An SSN will theoretically spend about 21 percent of its time on deployment, of which about 10 percent represents mission days.

In reality, submarines do not always match the Navy's notional schedules and cycles. In periods when submarines are in high demand, the IDTC can be shortened to return subs to sea more quickly. For the purposes of this analysis, however, CBO used the Navy's notional operating concept in its calculations.

The Navy's Concerns About Using More Than One Crew on SSNs

In written statements, Congressional testimony, interviews with the media, and briefings and information papers provided to CBO, Navy officials have raised various concerns about the concept of using more than one crew on attack submarines. Many of those concerns focus on the differences between dual-crewed Ohio class Trident missile submarines and single-crewed Los Angeles class attack submarines, which are the mainstay of today's SSN fleet. Those concerns cover three broad areas: maintenance, training, and the development of new crews.

Maintenance. As noted above, Trident submarines and their bases were designed and built to support a dual-crew concept. Many design features of the subs as well as the Trident Planned Equipment Replacement Program and the design of the subs' bases facilitate quick refits of a Trident submarine so the second crew can quickly return it to sea, thereby maintaining the submarine's relatively high operating tempo. Los Angeles class submarines and their home ports have none of those features, making it difficult for those submarines to use dual crews. Consequently, none of CBO's options envision using more than one crew for Los Angeles class submarines.

Training. Trident submarines perform essentially one mission: strategic deterrence. That mission begins as soon as the submarine leaves its home port and involves slow, quiet patrols in which contact with other ships and operations in other countries' waters are avoided. Training for that mission takes place in the extensive on-shore training facilities at Trident bases.

Attack submarines, by contrast, perform multiple missions, far from U.S. shores. According to the Navy, SSN crews need to conduct extensive at-sea training for those multiple missions before a deployment; shore training alone might not be effective. For example, Admiral Bowman, director of the Naval Nuclear Propulsion Program and the most senior submariner in the Navy, stated that the service would have to invest in more on-shore infrastructure and trainers to adopt a dual-crewing concept for SSNs. But that might not be enough, he argued: "There may be no substitute for at-sea training." Similarly, Rear Admiral Malcolm Fages, former director of undersea warfare for the Chief of Naval Operations, stated: "We are not at all sanguine that, even if we had unlimited funds, we could put in place a sufficiently robust training capability so that, in an off-crew status, the crews would be proficient to go to sea and do those missions."⁽¹³⁾

Developing New Crews. The Navy also argues that it could not put together new submarine crews quickly. If attack submarines were to begin operating with more than one crew, the Navy says, developing the first of those new crews would take at least 10 years. Although some development time would certainly be necessary, 10 years may be an overestimate. In testimony before the Congress, the Navy has vigorously pressed for a larger attack submarine fleet, which would also require more crews. It has not indicated that if the construction rate for attack submarines increased to two per year in the 2003 or 2004 budget--resulting in more submarines six or seven years later--the Navy's personnel system would be unable to staff those submarines.

Option IIA: Adapting the Blue/Gold Crewing Model to Attack Submarines

The discussion above demonstrates that applying a dual-crew concept to part of the SSN force would require developing new training and maintenance concepts for attack submarines as well as expanding shore-based infrastructure. Further, since not all attack submarines would have dual crews, the Navy would have to maintain two sets of procedures for its SSN force: one for single-crewed submarines and one for dual-crewed submarines. Offsetting those challenges, however, would be substantial gains in mission days and overall cost-effectiveness.

Under this option, the Navy would adopt a dual-crew operating concept for its new Virginia class submarines beginning with the one authorized in 2003, which would be commissioned in 2009. By 2015, nine Virginia class subs would be dual crewed; by 2025, 19 would have dual crews. Such a schedule would allow the Navy to develop the additional infrastructure that would be necessary for the concept.

How It Would Work. In this approach, two crews would take turns conducting maintenance and at-sea training before taking an attack submarine on a 180-day deployment. The first crew (say, the blue crew) would conduct maintenance and the required at-sea training and certification in the first 180 days, followed by a deployment of equal length (see Figure 10). Before and during the blue crew's deployment, the gold crew would be resting, visiting with family, and training on shore for its deployment. However, during the blue crew's maintenance and training period, the gold crew might also take the submarine out to sea for one-week periods to help maintain that crew's proficiency.
 

Figure 10. Notional Blue/Gold Deployment Cycle for an Attack Submarine

SOURCE: Congressional Budget Office.

NOTE: The small bands outside a crew's regular rotation phase represent one-week periods at sea to help maintain the crew's proficiency during the time it is undergoing on-shore training.

On the submarine's return from deployment, both crews would initially work on conducting necessary maintenance. After a couple of months, however, the gold crew would completely assume maintenance duties and begin its at-sea training and certification. That period would last 180 days and then the crew would take the submarine to sea for 180 days. On the sub's return, the cycle would repeat.

All of the dual-crewed submarines in this option would be based in Groton, Connecticut. The submarine base there has the most extensive facilities for maintaining and supporting attack submarines and thus would be best suited to handle a new way of operating the subs. That concentration, however, might lead to an excess of mission days provided by the Atlantic Fleet. To compensate, the Navy could transfer seven Atlantic-based submarines to the Pacific Fleet. By 2025, some of the dual-crewed submarines would be needed in the Pacific, given U.S. military strategy's increasing emphasis on Asia, as discussed in the 2001 Quadrennial Defense Review.

The Navy argues that the stealthy characteristics and technological capabilities of Virginia class submarines will be needed in the Pacific before 2025. Therefore, to put the dual-crewed Virginias in Groton--where they could perform missions only in the European and Central Asian theaters and the Western Hemisphere--might not be wise. However, this option assumes that the first four Virginia class submarines, which would not be dual crewed, would be assigned to the Pacific Fleet. Further, by 2016, the three submarines based in Guam would also be Virginia class subs (assuming that the Navy replaced the three Los Angeles class subs it is transferring to Guam after they were retired).

Mission Days and Force Levels. Using data from 1995 through 1998, the CJCS study assumed that a single-crewed submarine spends an average of 36 days per year on-station conducting missions. By the same methodology, a dual-crewed submarine as envisioned in this option would spend an average of 65 days per year on-station conducting missions--an increase of about 80 percent. (For a detailed discussion of how those numbers were calculated, see Appendix A.)

Those figures imply that the Navy could achieve the same number of mission days provided by a 68-submarine force with just 55 SSNs so long as it implemented its current plan--that is, the Virginia class program remained intact (see Figure 11). Achieving a force equivalent to 68 attack submarines in 2015 would require that nine of the Virginia class subs that the Navy is building now or intends to order by 2009 be dual crewed and that the remaining 46 Los Angeles class and Seawolf class submarines remain single crewed. The requirement for 18 Virginia class submarines by 2015 would be met with respect to mission days, though not actual subs. For the Navy to achieve the equivalent of 76 attack submarines by 2025, 19 of the 30 Virginia class subs that the Navy plans to have in service would need to be dual crewed and the other 36 SSNs single crewed.
 

Figure 11. Effect on Equivalent Force Levels of Using Dual Crews on Some Virginia Class Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that dual crewing would begin with the fifth Virginia class submarine and that each SSN operated by a dual crew would be equivalent to 1.8 SSNs with a single crew. Actual force levels would be much lower than the equivalent force levels shown here.

The Navy's plan assumes an average production rate of 2.2 subs a year between 2002 and 2020, compared with the current rate of one per year. After 2020, it assumes a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76 submarines.

SSN = nuclear-powered attack submarine.

a. Includes three SSNs based in Guam, each one of which is equivalent to about three SSNs based in the United States with respect to mission days provided.

If the Navy was unable to raise the construction rate from one submarine a year, however, the equivalent force level would decline over the next three decades, dropping below 55 by 2025.

Perstempo and Optempo. Compared with the way the Navy operates attack submarines today, Option IIA would reduce personnel tempo (perstempo) and increase operating tempo (optempo). The dual crews under this option would each have a perstempo of 34 percent over the two-year deployment cycle of a submarine, compared with a notional 48 percent for today's single crews. That difference might conceivably cause morale problems on single-crewed submarines. At the same time, the optempo of a duel-crewed SSN would rise from a notional 42 percent to 57 percent. In addition, by operating submarines more intensively, this option would exhaust the reactor of a dual-crewed SSN at around 25 years, reducing its notional service life by eight years compared with that of a single-crewed submarine.

Addressing the Navy's Concerns. This option for dual crewing attack submarines takes into account the Navy's concerns about maintenance and development of new crews. However, it only partially addresses the Navy's concerns about training.

Maintenance. The greater optempo of dual-crewed Virginia class submarines would most likely make additional maintenance necessary between deployments. Currently, the Navy nominally devotes 35 days per quarter to routine maintenance and upkeep of an attack submarine when it is not either deployed or in long-term maintenance or overhaul. The Navy could increase that number significantly--by about two-thirds, to 56 days per quarter--for dual-crewed submarines and still keep the ratio of routine maintenance to time at sea almost the same as for a single-crewed attack submarine (0.82 to 1 for the former compared with 0.87 to 1 for the latter). In addition, CBO assumed that the dual-crewed submarines under this option (as well as the multiple-crewed and Guam-based SSNs in Options IIB and III) would spend more time in shipyard-level maintenance than a single-crewed attack submarine does. For that reason, CBO did not assume that any substantial design modifications to the Virginia class would be necessary other than the ones the Navy is already planning.

Training. The Navy's plan for operating converted Trident submarines in an SSGN configuration raises questions about how much at-sea training is really necessary for attack submarines (assuming that the infrastructure for shore-based training is expanded). As noted in Option I, the Navy has stated in reports to the Congress and briefings to CBO that it believes an SSGN will be capable of performing most of the missions of an attack submarine, including strike, insertion of special-operations forces, undersea warfare, sea control, intelligence collection, offensive mining, and forward presence. Even so, the Navy plans to continue using the Trident's blue/gold crewing concept to operate those submarines, which would mean that essentially all crew training would be conducted on shore. If the Navy can implement that concept for SSGNs, it might also be able to do so for dual-crew attack submarines. Nevertheless, Option IIA would continue to provide a 180-day period before deployment in which the crew of an attack submarine could take the ship to sea for 28 days per quarter to perform at-sea training and certifications.

During that 180-day period, the alternate crew would have several opportunities to conduct at-sea training. It could spend about seven days per quarter training at sea when its submarine was in home port. Those at-sea training opportunities would mean that the largest gap between a crew's times at sea would be 180 to 190 days, compared with 130 days for the crew of an SSGN or 150 days for the crew of a Trident ballistic missile submarine.

Option IIA assumes that some investment would be necessary to increase the size of shore-based training facilities for SSNs. The principal training facility for attack submarines is located in Groton, Connecticut. As part of the overall downsizing of the submarine force, that facility was reduced. Thus, it could not easily accommodate training the extra nine to 19 submarine crews that would exist under this option without additional training equipment, instructors, classrooms, and associated infrastructure. SSN training facilities in San Diego or Hawaii, which are less extensive than those in Groton, would also need some additional equipment and facilities. CBO estimates that the total cost to expand SSN training and other facilities would be about $500 million.

Developing New Crews. This option would not attempt to employ dual crews for large portions of the attack submarine fleet quickly. Nevertheless, the Navy would have to recruit and retain nine additional crews by 2015 and 19 by 2025. Compared with its current plan for a 55-submarine force, the Navy would need an extra 380 officer billets and 2,000 enlisted billets by 2015. By 2025, an additional 800 officer billets and more than 4,200 enlisted billets would be necessary.

How much of a challenge would those additions pose for the Navy? CBO questioned Navy officials about whether the service could recruit and train 13 additional submarine crews by 2015 and 21 by 2025. In a thorough and highly detailed answer, the officials stated unambiguously that the Navy could meet those goals. Thus, the smaller addition--nine crews by 2015 and 19 by 2025--that this option would require to dual crew Virginia class SSNs beginning with the fifth ship should prove slightly easier to achieve.

Overall Cost-Effectiveness. Although this option would pose some policy challenges for the Navy, it would improve the cost-effectiveness of the SSN force. This option would cost an average of $130 million more per year than the Navy's plan between 2002 and 2025 (mostly for operations and support), but it would reduce the force's total cost per mission day by $0.5 million. Starting with a base force of 55 single-crewed attack submarines (including three in Guam) that provides a certain number of mission days, the average cost to meet the CJCS requirements under this option would be $2.2 million per mission day. By comparison, building more attack submarines to meet those goals would cost an average of $2.7 million per mission day.

Even if some design modifications were necessary to accommodate the dual-crew concept, the cost-effectiveness of this option would not change. For example, an additional $1 billion in design changes to the dual-crewed SSNs would keep the cost per mission day of the SSN force under this option at $2.2 million.

Option IIB: Using Three Crews to Operate Two Submarines

Adopting the Trident blue/gold crewing model is not the only way to improve the efficiency of attack submarines by using more than one crew. This option envisions an operating concept in which three crews would rotate between two Virginia class submarines on nine-month deployments. Under this option, eight submarines would operate with multiple crews in that manner by 2015 and 14 submarines by 2025. The principal advantage of this option is that it would change the crewing model for fewer SSNs than Option IIA would. However, that change would represent the most significant departure from the Navy's current practices for either attack submarines or ballistic missile submarines of the options that CBO examined; thus, implementing it would pose the greatest challenges for the Navy.

How It Would Work. In this approach, three crews would take turns operating a pair of Virginia class submarines. When one submarine was on deployment for 270 days, the other submarine would be in the same home port so that the crews not on deployment could use it for at-sea training.

The schedules of the two submarines would be divided into 90-day increments (see Figure 12). One crew (say, the blue crew) would deploy with the first sub for three months. Meanwhile, the gold crew would be training with the second submarine, preparing for deployment. The orange crew would not receive any at-sea training during those three months. Near the end of that period, the gold crew would be flown to the theater of the deployed submarine to exchange places with the blue crew.⁽¹⁴⁾ The orange crew would then assume control of the second submarine to prepare for its deployment. The blue crew, which had flown home, would rest and not receive any at-sea training during that second 90 days. After that second three-month period, the orange crew would rotate out to the deployed submarine, eventually bringing it back to the home port, while the blue crew was preparing the other submarine for its deployment. Each deployed submarine would stay at sea for a total of 270 days, three months longer than is the Navy's current practice.
 

Figure 12. Notional Deployment Cycle for Two Submarines Operated by Three Rotating Crews

SOURCE: Congressional Budget Office.

In contrast to the Trident model, the crews in this option would not all have the same operational experience. The blue crew would always conduct its deployment with the submarine that it had used for training. The other two crews would never have that advantage. The blue crew would always take a submarine on deployment and the orange crew would always bring it back. The gold crew would not do either; thus, it would never conduct long transits. However, all three crews would be at sea for comparable periods.

Mission Days and Force Levels. Submarines that used multiple rotating crews as envisioned in this option would spend an average of 73 days per year conducting missions over the course of their service life--twice the average for a single-crewed submarine. Achieving a force equivalent to 68 submarines by 2015 would require the Navy to begin this multiple-crewing concept with the Virginia class submarines authorized in 2004. By 2025, when 14 Virginia SSNs would employ multiple crews, the equivalent force level would exceed 76 (see Figure 13). Like Option IIA, this alternative would meet the requirement for 18 Virginia class submarines by 2015 with respect to amount of presence though not actual number of submarines.
 

Figure 13. Effect on Equivalent Force Levels of Using Multiple Crews on Some Virginia Class Submarines

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that three crews would take turns operating two Virginia class submarines and that each submarine crewed that way would be equivalent to two SSNs with single crews. Actual force levels would be much lower than the equivalent force levels shown here.

The Navy's plan assumes an average production rate of 2.2 subs a year between 2002 and 2020, compared with the current rate of one per year. After 2020, it assumes a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76 submarines.

SSN = nuclear-powered attack submarine.

a. Includes three SSNs based in Guam, each one of which is equivalent to about three SSNs based in the United States with respect to mission days provided.

Perstempo and Optempo. If, as this option assumes, crews spent half of their three-month training period at sea, their perstempo would be exactly 50 percent. That figure is slightly higher than the current perstempo for single-crewed submarines (48 percent) but essentially equal to the perstempo anticipated for the submarines that the Navy is stationing in Guam. The optempo of the multiple-crewed submarines would be 63 percent, higher than in Option IIA. That higher operating level would reduce the reactor life of a multiple-crewed submarine to 24 years, the shortest among the options in this study.

Addressing the Navy's Concerns. This option answers the Navy's concern about at-sea training better than Option IIA does, but it could require very controlled design and construction parameters for the submarines that would use multiple crews. Developing the additional crews would not be difficult, although the Navy would have to find suitable sites for exchanging crews in-theater. Maintenance, however, would be a greater challenge for the Navy than under Option IIA's dual crewing.

Maintenance. In this option, multiple-crewed submarines would spend nine months at sea, compared with six months for today's single-crewed SSNs. The operating cycle envisioned in this option would reduce the subs' ratio of maintenance time to at-sea time to 0.65 to 1 (from the current ratio of 0.87 to 1).

Keeping a submarine at sea longer increases the risk of not being able to maintain it in good working order. As mentioned in Option IIA, the crew of an attack submarine on deployment notionally conducts maintenance about 28 days out of 90. In practice, the crew is always performing some degree of maintenance on the ship's systems. Crew members can fix some problems, but others require the support of maintenance facilities on a tender or, better yet, at the home port. Although a submarine may encounter a difficult repair problem at any point in its deployment, staying at sea longer increases the probability that it will need the support of a tender to perform necessary maintenance during its voyage.

In an attempt to minimize maintenance problems, this option envisions adopting a more aggressive maintenance concept for the Virginia class submarines that would use multiple crews. Specifically, the Navy would need to replace important components at more regular intervals--as it does with Trident submarines--rather than wait until they failed or were about to fail. Although this option's notional operating cycle probably includes enough time to perform all necessary maintenance, sending the multiple-crewed submarines to sea with their important components replaced would help reduce the risk of breakdowns.

A further complication associated with this option involves scheduling the longer, shipyard-level maintenance periods (when a ship is unavailable for at-sea operations). The submarines with multiple crews would need to undergo such periods in pairs, in the same way that they operated.

Training. One advantage of this option is that it would provide up to 45 days of training at sea prior to each 90-day deployment. Thus, the longest period in which a crew would not be able to go to sea would be 90 days. That number is a considerable improvement over Option IIA, in which crews would spend at least 180 days without the opportunity to practice and maintain their skills at sea.

A disadvantage of this option's schedule, however, is that it would not provide enough time at sea to perform all of the training and certifications necessary for a submarine to deploy with an aircraft carrier battle group. Thus, the submarines that used multiple crews might be limited to independent operations. Although such operations represent the majority of attack submarines' missions, that limitation would create additional complexity in operating the SSN force and, therefore, in providing support to battle groups.

Another element of complexity is that in order for the at-sea training to be as effective as possible, submarines would have to be designed as well as operated in pairs to minimize any engineering differences between the sub used for training and the one taken on deployment. (Alternatively, the entire class would need stringent configuration controls.) Submarines, like other types of ships, are not all exactly alike. The Navy and submarine manufacturers try to ensure that each new sub incorporates the most up-to-date technology available. With a construction rate of one per year, every submarine is a little different from every other. How much that difference actually matters would depend on the specific technological discrepancies between two submarines. If the construction rate for attack submarines remained at one per year rather than rising to more than two, this option could still work, but it would require discipline in the engineering process from year to year.

How difficult would achieving such uniformity be? If two manufacturers each built one complete submarine every other year, this approach might be unworkable. However, the current teaming arrangement between Electric Boat and Newport News Shipbuilding, in which the same company builds the same sections for each submarine, has made it much easier to maintain such engineering discipline. Furthermore, the Virginia class submarine is the first Navy ship to be designed entirely by computer before any construction has begun. As a result, the first Virginia class submarine has had 90 percent fewer design changes during construction than the third Seawolf class submarine had at the same stage.

Developing and Exchanging Crews. This option would require far fewer additional crews than Option IIA: only four by 2015 and seven by 2025. However, the Navy would have to plan, and find appropriate locations for, the in-theater crew exchanges. Attack submarines on routine deployments periodically visit foreign ports as part of exercises as well as to give the crews some shore leave. Whether a foreign government would allow such visits for the purpose of exchanging crews is not clear. Missing a crew exchange would complicate the rest of the schedule of both submarines as well as potentially violate perstempo rules.

Overall Cost-Effectiveness. This option is every bit as cost-effective as Option IIA. It would cost slightly more than the Navy's current plan--an average of $70 million more per year between 2002 and 2025-- but, like Option IIA, it would reduce the average cost per mission day of the SSN force to $2.2 million. On the flip side, the policy changes required to carry out this option are more dramatic, and the risks that the Navy would assume are greater, than in any of the other options.
 

Option III: Base More Attack Submarines in Guam

Under this option, the Navy would continue to operate a fleet of at least 55 attack submarines, but it would station seven of them in Guam by 2015 and 11 by 2025. Unlike altering crewing concepts, basing another four to eight submarines in Guam would not be conceptually difficult to do. The additional submarines would operate in exactly the same way as those the Navy already plans to base in Guam. Moreover, although this approach would require some up-front spending to improve the infrastructure on Guam, it would produce a more cost-effective fleet than any of the other options examined in this study.

Mission Days and Force Levels

As explained in Chapter 1, a Guam-based submarine would spend an average of 106 days per year conducting missions, compared with 36 for a U.S.-based SSN today. Those additional mission days would come from a combination of reduced transit time and, especially, the different operating concept that the Navy plans to use for attack submarines stationed in Guam. Consequently, a force made up of seven Guam-based attack submarines and 48 other attack submarines would provide the same number of mission days as a force of 68 SSNs based in the United States. Similarly, a force of 11 Guam-based submarines and 44 other attack submarines would provide slightly more mission days than a force of 76 SSNs based in the United States (see Figure 14).
 

Figure 14. Effect on Equivalent Force Levels of Basing Eleven Submarines in Guam by 2025

SOURCE: Congressional Budget Office.

NOTES: This figure assumes that each attack submarine based in Guam would be equivalent to about three SSNs based in the United States. Actual force levels would be much lower than the equivalent force levels shown here.

The Navy's plan assumes an average production rate of 2.2 subs a year between 2002 and 2020, compared with the current rate of one per year. After 2020, it assumes a production rate sufficient to maintain a force of 55 attack submarines.

Dashed lines identify the force goals of 55, 68, and 76 submarines.

SSN = nuclear-powered attack submarine.

Furthermore, if the additional submarines assigned to Guam by 2015 were from the new Virginia class, they would almost satisfy the mission-day requirement associated with the goal of having 18 Virginia class submarines by 2015. That would be true even if the Navy was unable to increase the construction rate for Virginia class submarines above one per year. In that case, 11 Virginia class submarines would be operational by 2015; if three of them were based in Guam, the force could provide an equivalent number of mission days as 17 Virginia class submarines based in the United States. (Guam is not the Navy's only alternative for basing submarines outside the United States. For information on how other forward-basing options would affect force levels, see Box 3.)
 

Maintenance and Training

The Navy expects that any short-term maintenance necessary for its three Guam-based submarines will be done in that port. But more-major overhauls, requiring between two and 16 months in a shipyard, will be conducted in the continental United States or Pearl Harbor. If the Navy based more subs in Guam, it might want to build better repair facilities there. CBO assumed that the Navy would do so and included those costs in its analysis.

Shore-based training would be a more complicated issue. Guam does not have adequate training facilities, so the Navy would either have to build some there or fund a larger travel budget to fly the sailors from Guam-based submarines to training facilities in Hawaii or Connecticut (the current plan for the three subs that will be based in Guam by next year).

Other Issues

Although this option would enable the Navy to meet the CJCS force goals fairly easily with the currently planned fleet, it would have drawbacks. Basing a large force of attack submarines in Guam might prevent them from providing support to carrier battle groups that were preparing to go on deployment or from providing other services to the Navy fleet. In addition, the Navy would have to invest substantially in the shore facilities on Guam to accommodate a doubling--and ultimately a tripling--of submarines, crews, and their families. Even so, the quality of life of those crew members and families could suffer.

Battle-Group Support and Fleet Services. Half of the Pacific Fleet's aircraft carrier battle groups are based in San Diego. If the submarines transferred to Guam under this option were removed from San Diego, the SSN presence there would end, making it difficult for attack submarines to train with carrier battle groups and thus to support them during their deployments. That difficulty may not matter if more and more of the submarine force's missions are geared toward intelligence collection. However, the issue would not arise if the submarines transferred to Guam were taken from Hawaii rather than San Diego.

Regardless of the source of the transferred submarines, another effect of this option would be to reduce the availability of SSNs to assist other Navy units in training exercises. Attack submarines periodically serve as the opposition force for surface ships practicing antisubmarine warfare. This option would offer fewer opportunities for that, unless a surface unit took time for such practice during its deployment in the western Pacific (assuming that it was passing near Guam).⁽¹⁵⁾

Infrastructure. Probably the largest monetary cost associated with Option III is the additional investment that would be needed in Guam's shore-based infrastructure. To accommodate four to eight more submarines on the island (and their crews and families), the Navy would have to build a floating dry dock and additional pier spaces, barracks, stores, medical facilities, and schools--all of the things needed for a submarine base equivalent to the one in San Diego. Those additional facilities would cost $200 million, CBO estimates.⁽¹⁶⁾

Quality of Life. A potential difficulty with this option--as with the Navy's decision to base three submarines in Guam--is the quality of life of the sailors and their families. As noted in Chapter 1, Guam does not offer the same homesteading opportunities as submarine bases in San Diego and Pearl Harbor. At those large bases, it is relatively easy for members of a submarine crew to find other jobs in the Navy when they finish their sea tours.⁽¹⁷⁾ Thus, they and their families can put down roots and stay in one place longer than a few years. Such opportunities are few in Guam. That might become less true if the Navy adopted this option and invested in a much larger shore infrastructure. But even if that happened, the opportunities would not match those of places like San Diego or Honolulu--in part because there would be many fewer chances for the spouses of submariners to find jobs in the neighboring community.

If the Navy found that Guam-based duty led to much lower levels of retention for submariners, monetary bonuses might help. But there is no way to know for certain at this point because the Navy has not based submarines in Guam for more than 20 years and will not begin doing so until the end of the year.

Overall Cost-Effectiveness

Offsetting the possible drawbacks of this option is its cost-effectiveness--the greatest of any of the options in this analysis. Basing additional submarines in Guam permanently would not cost much more than the Navy's current plan for a 55-SSN force. The principal additional cost would be for infrastructure. In return, the cost per mission day of the SSN fleet would fall to $2.0 million, less than in any of the previous options and substantially lower than if the Navy built a larger submarine force. Even if the Navy found that it had to pay each crew member of a Guam-based submarine an extra $25,000 per year as a retention bonus, the cost per mission day under this option would not change significantly.
 

Implications of the Options

A number of conclusions emerge from the analysis of the options. First, transferring an attack submarine to Guam would be more cost-effective than building a new SSN, using an alternative crewing pattern, or converting and operating a Trident submarine in an SSGN configuration. Each mission day gained by building a new submarine would cost $2.7 million, by far the most expensive choice (see Table 5). Converting a Trident sub to an SSGN or using more than one crew to operate a Virginia class submarine would cost between $0.8 million and $1.2 million per additional mission day provided. Transferring an SSN to Guam would cost just $0.2 million for each mission day it added. Those results do not imply that transferring additional submarines to Guam is unequivocally the best approach, however. Other factors, such as those discussed in this study, must be considered in determining where an additional dollar spent on the submarine force should go.
 

The relative cost-effectiveness of the options is not particularly sensitive to changes in assumptions about operating or procurement costs. If a dual- or multiple-crewed attack submarine actually cost as much to operate as an SSGN or a Trident ballistic missile submarine (a reasonable upper limit) or even twice as much as a single-crewed submarine, Options IIA and IIB would still be cheaper per additional mission day provided than building new submarines would be (see Table 6). Further, if procurement costs for new submarines were lower than what CBO assumed, the relative cost-effectiveness of the options would be virtually unchanged. (And if procurement costs were substantially higher than CBO's estimate, the cost per additional mission day for submarine construction would worsen considerably relative to the costs for the alternatives.) Thus, to the extent that the costs of producing or operating attack submarines are uncertain, all four options would still be substantially more cost-effective for the Navy than building a larger submarine force would be.
 

A second conclusion of this analysis is that if the official force goal remained at 55, these options could help delay for many years the need to increase the production rate for SSNs. The options assume that the Navy will implement its long-term procurement plan to keep the size of the attack submarine force at 55. However, as Chapter 1 illustrated, carrying out that plan could be difficult because of its cost.

If the construction rate remained at the current level of one submarine per year, for how long could the approaches represented in these options maintain an SSN force equivalent to 55? Option I would sustain that level until 2023 (see Figure 15). But because of the six-year interval between authorizing a new submarine and fielding it, the production rate would have to increase to two or more SSNs per year in 2017. Under Options IIA and IIB, production would have to increase in 2013 or 2021, respectively, to maintain a force equivalent to 55 SSNs--assuming that all new Virginia class submarines after the fourth ship were dual or multiple crewed rather than the smaller numbers envisioned in the options. Finally, if the Navy based as many as 12 SSNs in Guam (probably the largest number it might reasonably want stationed there), the production rate would not have to increase until 2022. Under all of those scenarios, however, the SSN force would fall below 55 actual submarines (as opposed to their equivalent in mission days), which is the wartime requirement stated in the CJCS study.
 

Figure 15. Equivalent Force Levels Under Various Options, Assuming a Construction Rate of One Attack Submarine per Year

SOURCE: Congressional Budget Office.

NOTES: See the text for a description of the options.

The horizontal dashed line identifies the force goal of 55 submarines.

SSN = nuclear-powered attack submarine.

a. Equivalent force level assuming that all new Virginia class submarines after the fourth ship use dual or multiple crews (rather than the smaller number of submarines included in the option).

b. Equivalent force level assuming that 12 attack submarines--about two squadrons--are based in Guam (rather than the 11 submarines included in the option).

A third conclusion of the analysis is that adopting the new crewing concepts in Options IIA or IIB would require the Navy to make substantial changes in the way attack submarines operate, both as stand-alone units and as part of broader fleet operations. However, such changes do not appear to be any more radical--indeed, in some ways are less radical--than what the surface Navy is proposing with the new DD(X) destroyer, whose crew would eventually be one-third the size of a destroyer crew today. If the Navy executes that program as envisioned, those ships may need wholesale changes in crewing concepts, watch standing, damage control, supervision, training, and maintenance.

Even so, adopting the notional crewing approaches in Options IIA or IIB would require careful planning and analysis. For example, the Navy might want to try a pilot program using one or two submarines on each coast before committing to such alternative operating concepts for Virginia class submarines. However, the analysis of those options suggests that although carrying them out would require a substantial departure from the way the Navy operates attack submarines now, the dual- or multiple-crewing concepts do not appear to be impossible, or even infeasible, to implement. Along with the other options, they represent several ways to bridge the gap between the Navy's actual or planned force structure and its desired force structure 15 or 25 years from now.

1. For details of how CBO made those calculations, see Appendix B.

2. Information paper provided by the Navy to CBO, February 4, 2001.

3. See the unclassified portions of Department of Defense, Office of the Under Secretary of Defense for Acquisition and Technology, Assessment of Potential Benefits of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered Guided-Missile Submarines (SSGNs), August 1999. (This is the second of two reports on this subject. The first is Analysis of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered Guided-Missile Submarines (SSGNs), June 1999.)

4. Although the Navy has used such an operating concept for ballistic missile submarines, it has not done so for attack submarines.

5. DoD appears to have excluded port visits from those numbers, so CBO did as well. Port visits are necessary to give the crews of attack submarines liberty from being cooped up underwater during a 180-day deployment. An SSGN crew would be at sea for only 90 days on a much larger ship.

6. If the Navy wants to maintain the planned size of the Trident fleet at 14, it will need a replacement for its Trident submarines when they begin to retire in 2026. At this point, however, it is far from certain what such a replacement would look like or how much it would cost.

7. Information paper provided by the Navy to CBO, February 4, 2001.

8. That estimate includes the cost of buying Tomahawk missiles to arm the SSGNs. Navy officials argue that they will not need new missiles because they plan to convert Tomahawks that are launched through torpedo tubes to ones that can be shot from VLS cells. Doing that might save about a billion dollars, improving the cost-effectiveness of this option.

9. For the purposes of this analysis, the Navy's plan does not include the four SSGN conversions that the President proposed to the Congress in February in the 2003 Future Years Defense Program.

10. A similar concept was used with the previous class of ballistic missile submarines.

11. Until recently, those figures were 77 days of patrol followed by 35 days of maintenance.

12. That will no longer be true beginning this autumn, when the first of three attack submarines is transferred to Guam. As explained in Chapter 1, the operating cycles of Guam-based SSNs will be more intensive than those of U.S.-based attack submarines.

13. See Admiral F.L. Bowman, "Remarks to Corporate Benefactors," Submarine Review (April 2001), p. 24. Rear Admiral Malcolm Fages was quoted in John G. Roos, "Weighing the Options: U.S. Navy Faces Tough Choices in Modernizing Its Attack-Sub Fleet," Armed Forces Journal International (April 2001), p. 54.

14. The concept of rotating crews to a forward-deployed submarine was suggested in Department of Defense, Analysis of Converting Trident-Class Ballistic Missile Submarines (SSBNs) to Nuclear-Powered Guided-Missile Submarines (SSGNs). As described in that report, the blue crew would take the SSGN on deployment and the gold crew would be rotated to the submarine halfway through its patrol, eventually bringing it home.

15. A relatively inexpensive yet highly effective solution to that problem would be for the Navy to purchase several diesel-electric submarines to serve as an opposition force on each coast for ships practicing antisubmarine warfare. See Congressional Budget Office, Budget Options (February 2001), pp. 137-138.

16. Even if CBO has greatly underestimated the cost of building a submarine base in Guam, Option III would still be far more cost-effective than the others in this study.

17. Although San Diego is not a large submarine base, it is home to three aircraft carriers and their battle groups.

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