Single-Purpose Warships for the Littorals

By Captain Wayne P. Hughes Jr., U.S. Navy (Retired)

Responding to Surprise

How can U.S. Navy ships, built for extensive lifespans, stay relevant in such a rapidly changing world? American warships are programmed to last as long as 30 to 40 years to amortize the considerable costs of their multiple capabilities. This a hazardous state of affairs; just consider the inaccuracies of the long-term projections we made in 1975 regarding how the now-contemporary operating environment would look geopolitically, economically, and technologically. This was well before the collapse of the Soviet Union, the rise of the People’s Republic of China, the onset of severe budget deficits, the widespread influence of cyber links and operations, and the development of robotic weapons—to name a few of the bigger changes.

The National Research Council warned about the consequences of depending on large, costly, long-lived warships in a study published in 2013:

In a cost-constrained environment, when envisioning a low-threat situation or scenarios where there is little risk of loss of life or ships being damaged, building fewer but more expensive weapon systems and multipurpose ships is economically rational. More capability can be provided at sea with fewer hulls, crews, logistics, and total life-cycle costs. When, however, there is a risk of that ship being damaged or sunk because there is a high probability of a tactical surprise attack, the reverse is true—that is, cost-effectiveness becomes “too many eggs in one basket.” A damaging hit on a DDG hull is degradation not just of the fleet’s air and missile defense capacity but also of ASW [antisubmarine warfare], antisurface, maritime interdiction operations, support for Marines ashore, and helicopter-related missions as well. Building more but less-expensive, single-mission ships may increase fleet resilience to absorb the impact of an unanticipated threat at sea, and provide more options for response through geographic dispersion as well as greater ship availability for quick modifications. 1

While the emphasis in this article is on the operational and tactical advantages of simpler, more affordable warships, the observations of the National Research Council are equally as important. Smaller ships that have resilience against technological surprise due to their easier-to-modify designs are less costly to replace than larger warships.

Perils of the Littorals

Foreign littoral waters have become an unsafe place to operate on the sea surface. 2 Although the bulk of U.S. naval action has been in coastal waters since 1950, their significance has increased with the rise of China, the continuing threat from Iran, and the recent ventures of other countries, such as Russia. In these narrow seas, early warning and constant alertness are harder to achieve. Depth of fire is lost for lack of sea room. The clutter of inlets, differing coastlines and islands, coastal shipping, fishing boats, and oil rigs are all factors that complicate both offensive and defensive tactics.

For many reasons, a single-purpose ship is far preferable to an open-ocean multipurpose ship in situations that require a vessel to sail in these dangerous areas. The advantage of the single-purpose ship can be clearly illustrated by using lost combat capabilities as the basis of comparison. Assume a notional multipurpose ship has four. These might be surface-missile warfare, antisubmarine warfare, mine clearance, and the employment of helicopters or unmanned aerial vehicles. Since there is a high probability that one modern antiship cruise missile will put either ship out of action, the advantage in missile combat is 4:1 in favor of the single-purpose ship; when the multipurpose ship is put out of action in a missile battle, the Fleet also loses all its other capabilities. This is a tactical measure of combat advantage.

From an operational or campaign perspective, we must take account of design efficiency and ship endurance. The hypothetical multipurpose ship has the advantage of performing four different missions when the chance of it being lost is small. Another benefit is that one propulsion plant moves all four combat capabilities. This operational advantage can be shown by using a new metric of lost mobile combat capabilities. To do that, we must now divide both ships into mobility and combat components. Assume that the space, manning, and cost of the mobility and combat components in a single-purpose ship are the same and the value of each is one unit. If we give a multipurpose ship its same four combat capabilities and assert its propulsion capability requires only two units to move its four combat capabilities, the single-purpose ship’s lead is reduced from 4:1 to 3:1. (The lost value of the single-purpose, mobile missile ship is two. The lost value of the mobile multipurpose ship in combat capabilities is four but the mobility loss is only two. The ratio of losses is therefore now 6:2 or 3:1.)

We should make one more comparison of lost value. A much-admired peacetime advantage of a large U.S. Navy multi-mission warship is that it carries the logistical support to stay at sea unreplenished for several weeks. The small missile ship should not carry sustainment for more than a short time because it is expected to fight in dangerous waters. Since it carries only a small missile load, it must return to base to rearm after a battle. Thus, the missile combatant should be supported from a base or tender that is close to the operating area. The littoral combat ship (LCS) will also be forward based, in places such as Singapore and Rota, Spain.

If the vessel carries substantial self-sustainment, it will lose that non-combat capability when it is put out of action. Taking the loss into account quantitatively, a third comparison might be the following, using the metric of lost sustainable, mobile combat capabilities. When sustainment—valued at two units of stores, fuel, food, and additional personnel—is added to the total loss of value, the new metric favors the single-purpose ship over the multipurpose ship in the ratio of 4:1 again. Sustainment built into a warship is no advantage if the ship is lost in action.

Support from Salvo Equations

Ships expose themselves to loss when they must fight to defeat an enemy. A different method of quantitative comparison—simple salvo equations that measure the performance of two opposing surface forces fighting in the missile era—can show the combat advantage of this. 3 According to the equations, if you have three times as many ships as I do, then for parity in fractional losses each of my ships must have three times the offensive power, three times the defensive power, and three times the staying power of your ships. Operationally speaking, if you put one of my ships out of action, I simultaneously lose its offensive power, its defensive power, and also its staying power value, since my crippled ship is no longer a threat to draw your fire. Thus, the number of ships in your battle force is the single most important combat property you can have.

These well-tested mathematical equations also show how a more numerous and distributed force has more tactical choices—for example, to conduct a swift-swarm attack, approach by stealth, or conduct a coordinated assault from several directions simultaneously. As the attackers, a fleet of small, lethal ships choose the time and place to hunt and strike. The burden of achieving an ever-alert defense thus becomes the enemy’s problem. 4

The equations demonstrate quantitatively that an unstable situation results when the staying power of a combat formation is small. The formation’s staying power is the product of the number of ships in it and the amount of missile hits needed to put one ship out of action. The U.S. Navy will have fewer and fewer ships in its blue-water fleet, and only a small capacity in each vessel to take missile hits and continue to fight. The consequence is a brittle, unstable situation.

A small change in the offense, defense, or number of ships on either side will change a result from total victory (no losses) to total defeat (all ships out of action) after only a minor change in the inputs. (This is a mathematical artifact of the equations, but most naval officers would agree that a numerically small force of big warships with little staying power is undesirable and probably is an unstable fighting unit.) For missile warfare, a more numerous force that is well trained for littoral combat will reduce our brittleness when fighting in dangerous waters.

The same weight of ordnance can put out of action the bigger multipurpose ship as the small missile ship. For example, in World War II, one torpedo hit could cripple anything up to a 12,000-ton cruiser and sometimes sink it. The USS Stark (FFG-31), HMS Sheffield , and SS Atlantic Conveyer were ships of significant size that were rendered ineffective in the 1980s after one Exocet missile hit. Although there are no combat data for a warship of 10,000 tons hit by a missile, information from World War II and more recent experimental data suggest that one missile will usually put a DDG out of action. 5

A Tale of Four Cushing s

The meaning of “multi-mission,” “multi-capability,” “multi-function,” or “multipurpose” ship is clear. But no definition of “single-purpose warship” is entirely satisfactory. Every warship’s employment will change, depending on whether current American policy toward another state, such as China, is at the moment one of cooperation, competition, confrontation, or conflict. The evolution of the functions of “single-purpose” Navy vessels, all named Cushing , epitomizes why the term’s meaning is opaque by nature.

In 1952, I was assigned to the USS Cushing (DD-797), my first destroyer, a 2,500-ton multi-capability ship. Although she was assigned many tasks, she was built for one purpose: to escort bigger, more valuable vessels. A member of the large Fletcher class of destroyers, she had been commissioned during World War II when destroyer flexibility was already well established. Even though Fletcher s were designed to protect aircraft carriers or amphibious ships, it became known they were also quite effective in night battles, most famously in the Solomon Islands under the leadership of Rear Admirals “Pug”Ainsworth and “Tip” Merrill, and Commanders Arleigh Burke and Fred Moosbrugger.

Upon arriving in early 1943, after six months of mediocre battle performance, Burke pointed out that radar gave the U.S. Navy the potentially decisive tactical advantage; the torpedo, not the fast-firing 5-inch gun, was the decisive weapon; and fighting in a column formation was a foolhardy carry-over from prewar daytime tactics. When his new tactics were adopted, U.S. destroyers started to win clear-cut victories over Imperial Japanese Navy warships in the littorals of the central and upper Solomons. (It is no small irony that DD-797 was named for the USS Cushing [DD-376], a 1,500-ton prewar destroyer that had been sunk fighting 30,000-ton Japanese battleships in the first night battle of Guadalcanal before the Navy learned how to attack with cruisers and destroyers.)

During most of my years of active duty from 1952 to 1982, destroyers and cruisers were categorized as “major fleet escorts” well after they had developed an independent missile-attack capability. A modern DDG epitomizes the multipurpose ship. However, destroyers originated as single-purpose ships, starting with the first USS Cushing (TB-1), a 120-ton torpedo boat (TB) commissioned in 1890. Although she was designed to join in swarm attacks in coastal waters against enemy battleships, she was sent to patrol the Cuban coast during the Spanish-American War in 1898.

All big navies knew that something had to defend battleships against TBs. “Torpedo boat destroyers” were soon invented, and well before World War I they subsumed the TBs’ purpose. Destroyers would practice fighting each other—not for their own sakes, but to attack or defend against attacks on battleships and transports. The second USS Cushing (DD-55), which displaced 1,200 tons, was typical of destroyers commissioned before and during World War I. In short order the destroyer role was expanded to protect warships and commercial vessels from submarine attacks. By the time I reported to DD-797, destroyers performed air-defense and radar-picket duty as well.

Thus, it is no simple matter to say what one means by a single-purpose ship. Single-purpose ships like the first Cushing (TB-1) are exemplified by the American Pegasus -class hydrofoils, fast-attack patrol boats in service between the late 1970s to early 1990s, and the contemporary Chinese Type 022 Houbei designs. Both the Pegasus and Houbei classes replaced torpedoes with surface-to-surface missiles. Both classes displace 250 tons and were designed for a single deadly purpose. As the 21st century progresses, doubtless a new single-purpose combatant will be adapated for ancillary employments—if and when we build and deploy these small ships. But auxiliary tasks must not distract from their utility as low-cost, high-lethality missile combatants that can be put at risk in dangerous waters.

The Case with Real Ships

A new DDG will cost about $2 billion. For that price it has many valuable capabilities, more than the four in our notional multi-mission ship. A DDG has efficient propulsion and sustainment to move it and maintain its combat capabilities on long and distant peacetime deployments. If we prorate the cost of the modules that support their multi-mission combat capabilities, the Navy’s two LCS designs both cost on the order of $600 million each. Both designs are speedy, but neither has a propulsion system designed for long endurance. An LCS is not intended to stay at sea unreplenished for very long, so the best way to operate a squadron is from a forward base at places like Singapore, Sasebo, Darwin, Bahrain, Rota, or Naples.

A blue-water frigate epitomizes the ship Secretary of Defense Chuck Hagel described to replace the LCS. His imagined frigate will cost as much as an LCS: $500 million or more. It will have about the same number of billets and must be multipurpose. Its design can be adapted from many existing foreign frigates, some of which are being built now in U.S. shipyards. The new frigate should serve as a blue-water combatant to replace our lost DD-963s and FFG-7s. We can buy four or five new-design frigates for the cost of one new DDG. Frigates will help keep our blue-water fleet numbers up for operations in carrier strike groups (CSGs), expeditionary strike groups (ESGs), and surface action groups.

But the new frigates are not suitable for fighting in the littorals. A smaller missile ship must be a low-cost, small-crewed, single-purpose warship designed exclusively for missile combat in dangerous waters such as the China Seas, the Yellow Sea, the eastern Mediterranean, the Persian Gulf, the Arabian Sea, and perhaps very soon the Sea of Japan, the Baltic, and the Black, Red, or Aegean seas. A flotilla of, say, 8 to 16 will be forward based in the critical area hosted by U.S. Navy friends or allies. They should have simple, affordable hulls and unremarkable propulsion plants. Operational stay time will be one or two weeks of peacetime steaming, or a few days for each sequential wartime-strike mission. Affordability and a small combat crew are dominant considerations, because one missile hit is certain to render the vessel useless. After a hit, the tactical aim should be to abandon the ship and save the crew.

No existing corvette is quite the correct design, because small navies have to load their limited number of surface ships with multiple missions, including search, patrol, coast guard duties, and many others. A suitable goal for an austere, single-purpose, uniquely American missile design is a 500-ton ship costing $100 million. If the goal is unachievable within our procurement system, it does not diminish the need for a littoral combatant that is better suited than the LCS—which was, after all, our first attempt to produce such a ship in many years.

Pessimistically speaking, a missile corvette could require two or more designs in tandem to achieve my minimalist goal. For comparison I will assume our first such ship displaces 1,000 tons and costs $200 million. If so, for $200 million we can still have ten of them for the cost of one DDG, and three of them instead of one LCS. With the $10 billion budget wedge from the 20 LCSs that were recently canceled, we can buy ten fleet frigates for sustained open ocean operations, and 25 first-generation missile corvettes for littoral combat in waters where more costly ships should not be put at risk.

Eventually, the Navy might decide to buy single-purpose antisubmarine warfare (ASW) ships, mine countermeasures ships (MCMs), and naval gunfire support ships. Meanwhile, the 32 LCSs it is building can play their intended roles for inshore ASW, MCM, and countering swarm attacks.

Furthermore, other studies have demonstrated that many ships in a U.S. Navy component for littoral operations need cost only a small fraction of the procurement and operating costs of the whole Fleet, on the order of 5 percent of funding for Navy shipbuilding and conversion, military personnel, and operation and maintenance. 6 Despite its small budget share, the littoral fleet will increase its total numbers and availability for a worldwide presence. Small combatants are ideal for cooperative operations and joint training with friendly coastal navies around the world.

Ships for fighting in the littorals are a niche capability to fill a void. They should be numerous, yet take only a small budget fraction. The expensive part of the Navy will continue to ensure safe sea lines of communications for all peaceful nations and to project and sustain large quantities of combat power onto land at select locations.

In summary, three basic forms of quantitative analysis all demonstrate the marked advantage of single-purpose missile ships for littoral combat:

• Measured in lost value after being put out of action, the advantage of a single-purpose ship is roughly proportional to the number of capabilities carried in a multi-mission ship.

• Salvo equations show parametrically that the number of ships in a fighting force is its most valuable property for missile combat.

• When procurement cost is explicitly measured, the equal-cost numerical advantage of single-purpose missile ships stands out.

New Tactics and Methods

A more general discussion of the littoral environment would include the logistical vulnerabilities of land bases and the mobile combat logistics force, which are specific to enemies and geography. The dialogue would also have to address the intimate connection between an air campaign above and an undersea campaign beneath the surface. An interesting relationship between the air and surface battles is a reverse of what is true of valuable multi-mission ships that are severely disadvantaged vis-à-vis aircraft attacks. Small, single-purpose vessels can pose a threat to enemy ships at sea that an opponent can ignore only at his peril. If his aircraft undertake a difficult search-and-attack effort against them, this will consume air resources that will be subtracted from his battle for air superiority.

The details of every littoral operation are different, but it is obvious that each requires new and flexible Fleet doctrine and tactics. New methods of command and control will be important to naval tactics. CSGs and ESGs cannot function and fight without detectable electromagnetic radiations within the ideal of “network-centric warfare.” But command-and-control of flotilla operations can exploit new ways of fighting under what might be called “network-optional warfare,” a term coined by Professor Don Brutzman, who is pursuing a variety of technologies to enhance semi-silent and undetectable operations at the Naval Postgraduate School (NPS). We can become adept at infrequent, hard-to-detect emissions to conduct sudden attack in the littorals. Achieving proficiency and cooperative action will take tactical development and training, done most usefully in the waters where fighting may ensue, and in collaboration with the countries with prior experience that we are supporting with a combined “1,000-Ship Navy.”

In a 1995 Naval War College Review article, “The Power in Doctrine,” I wrote,

The U.S. Navy does not have current tactical doctrine for fighting a fleet on the littoral, nor does it have substantial joint, campaign-level doctrine. . . . This contrarian tactician’s point of view is that a new “play book” is needed for winning battles along a hostile shore. 7

That nothing has changed since 1995 was demonstrated by recent discussions at NPS with Swedish Navy and Marine officers who have trained and are proficient in the Baltic. They described the differences in coastal environments of Swedish, Norwegian, Finnish, and Danish waters and called them the “extreme littorals.” The Swedish officers pointed out the many advantages they train to exploit. They regard their coastal waters as a defenders’ advantage. Rather than seeing fishing boats, coastal trade, and other coastal clutter as liabilities, the Swedes suggest that for an aggressive defense a nation may take a proactive approach to clear or augment the clutter to its advantage.

My message is identical to theirs: Know your tactics, know your enemy, know the territory, and know how to fight with friends in ways quite different from our blue-water fleet experience.

As Rear Admiral Benyamin Telem of the Israeli Defense Force has said, “Under no circumstances should ships become big or expensive in equipment to the extent that their defense becomes a first priority requirement in itself. This would inevitably negate their offensive value.” Large, expensive warships and transports will and should comprise the greater part of our Fleet. When measured in displacement, delivery capacity, and cost, they provide large quantities of ordnance and troops proficiently. But a flotilla of missile ships is designed for fighting a war, not making war. Its special value is to help keep the peace by visibly affirming support for our allies, and deterring prospective enemies by overtly confronting them at a critical point in littoral waters. When our warships are intended to fight there, a flotilla of relatively inexpensive single-purpose ships is preferable to pricey multi-mission warships.

1. National Research Council, Responding to Capability Surprise: A Strategy for U.S. Naval Forces (Washington, DC: The National Academies Press, 2013), 73.

2. Skeptics of this statement should read: RADM Yedidia “Didi” Ya’ari, Israel Navy, “The Littoral Arena: A Word of Caution,” Naval War College Review , vol. XLVIII, no. 2, Spring 1995, 7–21. It will be republished in the Review ’s Summer 2014 issue.

3. For an introduction to salvo equations, see: CAPT Wayne P. Hughes Jr., USN, Fleet Tactics and Coastal Combat (Annapolis: U.S. Naval Institute Press, 1999), 268–90. CAPT Wayne P. Hughes Jr., USN, “A Salvo Model of Warships in Missile Combat Used to Evaluate Their Staying Power,” in J. Bracken, M. Kress, R.E. Rosenthal, Warfare Modeling (Danvers, MA: John Wiley & Sons, 1995), 121–144. Entry for “Salvo Combat Model,” Wikipedia.

4. Hughes, Fleet Tactics , 271, Figure 11.

5. Ibid., 156–163.

6. Jeffrey Kline and CAPT Wayne P. Hughes Jr., USN, “A Flotilla to Support a Strategy of Offshore Control,” Technical Report NPS-OR-13-0001R, FOUO, January 2013.

7. CAPT Wayne P. Hughes Jr., USN, “The Power in Doctrine,” Naval War College Review , vol. XVLIII, no. 3, Summer 1995, 29.

Dean Emeritus, Professor, and Captain Hughes teaches campaign and tactical analysis at the Naval Postgraduate School in Monterey, California. He wrote Fleet Tactics and Coastal Combat , published by the Naval Institute Press, and is a Proceedings distinguished author.


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