Current U.S. Navy ship design criteria and practices can produce capable blue-water warships, but what the Navy needs is a small combatant specially suited for littoral warfare. An analysis of other countries’ small combatants—this is the Israeli Sa’ar 5—might point the way.
The surface combatants currently deployed by the U.S. Navy include Ticonderoga (CG-47)-class cruisers, Arleigh Burke (DDG-51)- and Spruance (DD-963)-class destroyers, and Oliver Hazard Perry (FFG-7)-class frigates. They were designed between 1967 and 1984 to meet the strategic, operational, and tactical realities imposed by a monolithic Soviet threat, and they are by far the most capable mix of blue-water warships in the world. For littoral warfare, however, they are overpriced, overmanned, and vulnerable.
The Arleigh Burke-class destroyers, for example, are unquestionably the world’s most capable and advanced combatants, but their expensive air-defense capability and long-range, low-frequency, deep-water sonars often have limited value in littoral warfare. Their single 127-mm gun mount has a low rate of fire, short range, and limited lethality—and although they are relatively resistant to some “cheap kill” threats, their survivability against major antiship weapons is still very low. In littoral areas, an Arleigh Burke becomes a large, expensive, politically vulnerable target.
The Ticonderoga- and Spruance-c\ass cruisers and destroyers suffer similar problems and limitations. The smaller Oliver Hazard Perry-class frigate has the advantages of a smaller draft, lower annual operating costs, and a smaller crew, but it lacks a major-caliber gun, has an air-defense system that can easily be saturated, and has relatively poor survivability.
Only one class of small combatants is available at present for littoral warfare—the Cyclone (PC-1) class. The small Cyclone class was developed:
- For special warfare in littoral waters, where it can sustain and deliver a SEAL team
- For conventional patrol of littoral waters lasting up to ten days
Unfortunately, the Cyclone, a derivative of a 1970s-vin- tage Vosper fast-attack craft (FAC), is virtually unarmed. As originally delivered to Egypt, this FAC carried a 76- mm Oto-Melera gun mount forward, a Breda twin 40-mm automatic gun mount aft, and four long-range, heavy Ot- tomat antiship missiles amidships. It had a surface-search radar, two radar fire-control channels, and a capable electronic warfare (EW) system. In contrast, the PC-1 class as delivered carried only a navigational radar, a very simple aircraft-derivative passive EW system, a manual Stinger missile firing post, and two pintle-mounted 25-mm guns.
With a deep draft, only moderate speeds, limited stealth characteristics, and a combat system that can provide neither fire support for SEALs ashore nor self-defense against antiship weapons, the Cyclone class is inadequate for special warfare. Its lack of armament makes it unsuitable for any mission except patrolling in a benign environment. Further, its obsolescent, poor-seakeeping, round-bilge hull form means that even that mission can be performed only under favorable weather conditions.
Many other countries have small combatants that have been developed for littoral warfare. Of these, Israeli and Russian small combatants are the best candidates for analysis from which the United States could draw beneficial insights—Israeli designs because they have the most technically advanced combat systems, and Russian designs because they are deployed most widely by potentially hostile Third World navies.
Past Attack Craft
The Sa’ar 4.5, the latest in a series of Israeli FACs first conceived in the early 1960s, has a point-defense Mk 15 20-mm close-in weapon system forward, and a 76-mm Oto-Melera gun mount aft, with 20-mm and 12.7-mm pintle-mounted guns located port and starboard of the superstructure. It carries a mix of Harpoon and Gabriel antiship missiles, plus 32 vertically launched Barak air-defense missiles. Covered with radar-absorbing material, the specially shaped superstructure and enclosed mast of the Sa’ar 4.5 mounts a high-data-rate 2D/3D air/surface search radar, a commercial navigation radar, three channels of fire control (two radar and one electro-optical), a two-man gun director, numerous electronic warfare and communications antennas, and four sets of fixed short-range decoy launchers. A large, multitube, trainable and elevatable decoy launcher is located aft.
To reduce its thermal signature, the Sa’ar 4.5’s diesel engines exhaust below the waterline at high speed; it also employs special coatings and a topside water spray system. The Sa’ar 4.5’s hull is based on a Lursen-style round- bilge hull form, based on the one used by World War II German “E” torpedo boats. It has a quadruple shaft propulsion plant, with each high-RPM propeller powered by a lightweight, high-speed diesel engine. The intact stability standards of the Sa’ar 4.5 are based on relatively low-velocity beam winds; hence its freeboard can be relatively low and its profile can be relatively high.
Israeli tactics call for fast attack craft to be used offensively. During the 1973 Yom Kippur War, task forces of four to six Israeli FACs struck the Egyptian and Syrian coastlines repeatedly at night. Today, such task forces would include at least one FAC or corvette with a helicopter for over-the-horizon targeting. Israeli FAC task forces historically have operated passively, using emission control, with over-the-horizon targeting data passed by secure communications or data link from a remote, shore-based central command post.
The Tarantul is one of the latest Russian fast-attack craft. Tactically, Tarantuls would be dispersed along a threatened coastline in protected anchorages, where they could be ordered out of port on very short notice under centralized, shore-based control. When in range of an over- the-horizon target, they would salvo their powerful battery of antiship missiles at the enemy, then turn and race for their home ports. Point defense weapons and chaff launchers face aft, designed to protect a disengaging Tarantul as it races toward shore. Its overall design sought speed and responsiveness in a cold, wet, rough environment.
The Tarantul can achieve speeds up to 50 knots at light displacements, thanks to its lightweight 32,000 BHP twin-screw, combined gas turbine and gas propulsion plant, with fixed-pitch propellers. The cruise gas turbines have two-speed reduction gears that allow them to operate at either cruise or high speeds. They also are mechanically cross-connected, so that one cruise engine can efficiently power both shafts. This means that the Tarantul can loiter at very low speed, then quickly transition to very high speed. The efficiency of the propulsion system—at moderate speeds—is relatively poor.
The Tarantul is relatively spacious because it has a beamy, deep hull. Hull depth was set by the relatively high freeboard required for safe operations in rough seas. The beam was set by the cumulative width required for the port and starboard missile launchers, which are located outboard of the centerline pilot house. The Tarantul’s missiles must be aligned directly with the target immediately before launch; therefore, the missile launchers are aligned parallel to the centerline.
The Tarantul was not designed for sustained operations. The time between overhauls for the main propulsion gas turbine engines and the reduction gears is very short; however, the Tarantul has soft patches in the deck over the machinery box, which permit relatively fast disassembly, removal, and replacement of the entire propulsion system. Like other international FACs, the Tarantul has a very limited on-board maintenance capability, but each of its weapon systems and sensors has a complete package of on-board spares, tools, and test gear, which provide a guaranteed number of warranted operating hours.
The Tarantul has excellent guns. The AK-176 76-mm gun mount combines a 120 round-per-minute rate of fire with a dual feed system, allowing it to switch rapidly between high-explosive, contact-fuzed and prefragmented, proximity-fuzed ammunition for surface and antiair warfare, respectively. The 76-mm gun mount also has a local control system, allowing it to continue firing if the ship loses electrical power. The two AK-630 30-mm Gatling guns also fire relatively powerful ammunition.
The Sa’ar 4.5 and the Tarantul have about the same full-load displacement, although with nearly twice the propulsive power, the Tarantul can achieve about 15 knots higher speed. The Tarantul, designed to remain operational in a more demanding open-ocean environment, has a relatively high freeboard. The major command spaces and the surface-to-surface missiles are located relatively far aft, near the ship’s center of flotation, where the impact of ship motions is minimized. By contrast, the Sa’ar 4.5 was designed for the relatively benign Mediterranean environment. It has low freeboard, a shallow hull, and only a single platform level, which render her virtually non- serviceable in rough conditions.
The Sa’ar 4.5 does have one advantage over the Tarantul. Most of the weather deck amidships and aft is open. In the Tarantul, the main deck is occupied by the large superstructure, the fixed missile launchers, and the intakes and exhausts for the gas turbines. The Sa’ar 4.5 uses its open weather-deck area for modular mission-related systems. Sa’ar 4.5s can mount portable davits for high-speed special warfare assault boats, in lieu of Gabriel surface-to-surface missile canister launchers, or a variable depth sonar and Mk 32 ASW torpedo tubes. Two Sa’ar 4.5s use the available deck area for a helicopter landing deck and hangar.
Observations about FACs
The fast attack craft is a limited endurance, single-mission platform, suitable for operation in moderate sea conditions. FACs can be configured for any one of a variety of primary missions:
- Electronic intelligence
- Surface warfare
- Strike warfare
- Antisubmarine warfare
- Special warfare
- Helicopter support
Theoretically, FACs can sustain missions of five-to-ten days, depending on the on-board fuel and stores, but noisy accommodations and uncomfortable ship motions have tended to reduce mission time. Because of limited personnel endurance, international navies generally do not refuel or replenish FACs at sea, although it is feasible to do so. The operational inflexibility of quadruple-screw diesel propulsion plants, which cannot cruise efficiently at very low speeds, often combines with environmental constraints to limit diesel-powered FACs to two to three days of continuous operation.
FACs can be relatively stealthy, although the requirements for high speed and low acoustic signatures tend to be mutually exclusive. Most are designed to meet the same damage-control and fire-fighting standards as larger combatants, but their small size means that they are especially vulnerable to catastrophic damage from antiship weapons. FACs with conventional round-bilge hull forms can remain fully operational up to sea states 3 to 4 and will be capable of limited operations at reduced speeds and selected headings in sea states 5 to 6. FACs can survive operations during sea state 7 or higher.
Foreign FACs can be procured for $90-120 million, primarily depending on the capability of their command-and-control and electronic-warfare systems. A lead FAC constructed in the United States probably would require a $150-200 million commitment, assuming the use of off-the-shelf weapons and sensors, with subsequent FACs delivered at $120-150 million. Based on cost experience with the PC-1 class, a basic hull/mechanical/electrical FAC platform could be delivered by U.S. shipyards at a cost of less than $20 million.
Corvettes
Corvettes are larger than FACs and therefore provide improved seakeeping and sustainability. Because of the additional displacement, deck area, and support systems capability that can be allocated to payload, corvettes can provide some degree of multimission capability or can mount larger, more capable weapons and sensors.
The Israeli 1,275-ton Sa’ar 5 has more combat power than virtually any NATO frigate. Its Israeli-conceived, but U.S.-designed and -constructed, state-of-the-art hull mounts a largely Israeli combat system developed to meet their operational requirements. The multimission Sa’ar 5 is optimized for surface and strike warfare, but it also has antisubmarine, special warfare, and electronic warfare capabilities.
The Sa’ar 5 has a very capable hard and soft kill point- defense capability that combines five primary channels of fire control for 64 vertically launched Barak intermediate/point-defense missiles, a 20-mm Mk-15 close-in weapon system, two remotely controlled 25-mrn Gatling guns (each with its own fire-control system), and four trainable and elevatable launchers for active decoys, chaff, flares, and obscurants, plus a very capable active and passive electronic warfare capability. The Sa’ar 5 probably will mount eight antiship Harpoon missiles and eight new Israeli ramjet-powered, supersonic cruise missiles for shore strike. The Barak missiles also can be used in the surface-to-surface role with conventional high-explosive warheads and contact fuzes.
For antisubmarine warfare, the Sa’ar 5 can carry a keel-mounted sonar, a variable- depth sonar, a towed array, two Mk 32 torpedo tubes, Mk 46 or Mk 50 torpedoes, and an ASW helicopter. The Sa’ar 5 mounts a short-range 2D/3D high-data-rate air-search radar, a 2D medium-range air-search radar, a surface-search radar, and a commercial navigation radar, in addition to three radar fire-control channels and two optronic fire-control systems. The Sa’ar 5 can carry swimmer-delivery vehicles and landing boats for use in the special warfare role. It has a hangar and landing deck and normally will operate with one helicopter optimized for surface warfare.
The Sa’ar 5 probably is the stealthiest surface combatant currently operational in any navy. It uses stack cooling, special low-reflective coatings, and an NBC wash-down system to reduce its thermal signature. Like U.S. Navy combatants, it has relatively large diameter, low RPM propellers, Prairie- Masker air emission system, and special foundations to reduce its acoustic signature.
The hull, superstructure, and masts of the Sa’ar 5 incorporate extensive shaping and are selectively covered with radar-absorbing materials. High, protective, sloped bulwarks mask all topside deck fixtures, boats, and canister-launched missiles. The radar-signature-reduction features of the Sa’ar 5 will not defeat space-based detection systems, but they will reduce the acquisition range of enemy ship, aircraft, and missile radars significantly and make passive and active decoys far more effective.
The Sa’ar 5 has a state-of-the-art twin-screw combined- diesel or gas propulsion plant, a lightweight steel hull, aluminum internal decks and bulkheads, and an aluminum superstructure. To minimize ship size and cost, the Israeli Navy chose not to incorporate a second LM2500 boost turbine, in part because the use of more highly loaded, higher-RPM propellers would have increased the Sa’ar 5’s acoustic signature unacceptably. The Sa’ar 5 also has limited range at flank speed. Two boost engines, with a mechanical cross connection between shafts, allowing operation at 15 to 30 knots on a single boost engine, and a larger fuel-oil load would have increased the acquisition cost of the Sa’ar 5 by more than 5% but also would have increased its operational flexibility.
The Sa’ar 5 has a remarkably small crew of 74, of which an unusually large proportion are officers or senior noncommissioned officers. Manning probably is based on the assumption that all facilities maintenance, and most preventive and intermediate maintenance, will be conducted in port by support personnel. The watchstanding routine probably provides a minimal allowance for weekly military or housekeeping duties while under way. Other navies would require a much larger crew, with more administrative spaces, on-board shops and storerooms, and more generous habitability. This would increase the volume of the Sa’ar 5—as well as its life-cycle cost—but would have limited impact on its acquisition cost.
The Sa’ar 5 is about one-sixth the displacement of an Arleigh Burke-class destroyer. It requires about one-fifth the operational personnel, and its procurement cost is about one-quarter that of an Arleigh Burke. By international standards it is over-capable, undersized, undermanned, and far too expensive. Conversely, it is judged to be the world’s most survivable surface combatant, combining low signatures with an exceptional hard and soft kill point-defense capability.
The Grisha Ill-class corvette is one of the latest Russian combatants designed for littoral warfare, specifically, for multiship stop-sprint ASW operations in confined waters around vital ports. Its very compact, lightweight 38,000 BHP triple-screw propulsion plant was designed for stop- sprint tactics. Its sprint speed is more than 36 knots, but it has limited range. It has four high-RPM, 5,000-BHP diesels, two port and two starboard, and an 18,000 BHP gas turbine on the centerline. It uses lightweight, efficient, but very noisy high-RPM fixed-pitch propellers. The diesels have two-speed reduction gears for use during both cruise and boost operations. To maintain directional control with the ship dead in the water during ASW search operations, the Grisha III has a stern thruster system.
The Grisha III mounts a very large and powerful 3 kHz active keel sonar and an effective 7-9 kHz variable-depth sonar (VDS). The VDS is located in the hull, just aft of the machinery box, where the ship pitch motions are minimized. When the ship is dead in the water, it takes less than two minutes to deploy or retrieve the VDS. The active hull sonar remains effective only up to a speed of eight knots.
To attack a target, other nearby Grisha Ills are vectored toward the detected submarine. Fire-control data are provided from the searching to the attacking ships by data link. The attack is accomplished using the Grisha Ill’s four 21-inch heavyweight ASW torpedoes and its two RBU-6000 multiple-tube ASW rocket depth charge launchers, which are particularly effective against a submarine sitting on the bottom or operating in shallow water.
For point defense against aircraft and antiship missiles the Grisha III has an SA-N-4 missile launcher forward and a twin 57-mm gun mount and an AK-630 30-mm Gatling gun aft. It has air- and surface-search radars, three fire-control radars, an electronic warfare system, and four chaff launchers.
Like all Soviet weapon systems, the Grisha Ills were warranted at delivery and designed to require an absolute minimum of organizational-level maintenance. Consequently, they have relatively small crews. They are tight ships, with very limited access to equipment for in-place maintenance. However, each radar or sonar equipment room includes racks of carefully organized boxes containing the predetermined spare parts required to provide the warranted number of operating hours and the appropriate tools and test equipment needed to keep the systems operational.
Because of the overall tightness of the Grisha Ill’s design and the lack of future growth margin built into vital auxiliary systems, it would be very difficult, if not impossible, to upgrade the ship at mid-life. In all probability, Russian designers assumed that the Grisha III would have a limited life span, determined by two warrantee cycles for its installed weapons and sensors, rather than the much longer theoretical life span of its hull, mechanical, and electrical systems.
Observations about Corvettes
Corvettes are capable of carrying larger combat systems than FACs. It is feasible, as in the case of the Grisha III, to develop either a highly capable single-role corvette, or, as in the Sa’ar 5, a multimission corvette. Heavier and longer than FACs, corvettes provide superior seakeeping and can remain fully operational up to sea state 4 to 5. They are capable of limited operations at reduced speeds and selected headings in sea states 6 to 7 and can survive sea state 9. Because of their superior seakeeping, their more flexible propulsion plants with more efficient, low- speed performance, and their superior habitability, corvettes are capable of undertaking longer missions than FACs. Nevertheless, mission endurance also depends on system reliability, and corvettes generally do not have a capability of more than minimal preventive or corrective maintenance. Furthermore, corvettes are no more survivable than FACs against major antiship weapons, although they may maintain some operational capability after being attacked by low-lethality weapons. Foreign corvettes can be acquired for about $150-200 million, depending on the capabilities of their combat systems. A lead corvette constructed in the United States might cost $250-300 million—assuming the use of off-the-shelf weapons and sensors and the availability of a preexisting command- and-control system.
Technological Advancements
The design of future FACs and corvettes could improve by using a deep-Vee hull form. The deep-Vee provides exceptional seakeeping and highly competitive calm-water powering. Waterjet propulsion—incorporated in the latest Swedish FACs—also is attractive because it places the engine room aft and provides lower acoustic signature, shallow draft, excellent low-speed loiter performance, and exceptional maneuvering capability. Recent corvette-sized, high-speed European car ferries have combined the deep-Vee hull form with waterjet propulsion and lightweight aluminum hulls, a combination that could be applied to future U.S. Navy FACs and corvettes.
Conclusion
Attempting to impose the U.S. Navy’s current ship design criteria and practices and its approach to manning, training, and maintenance on future small combatants for littoral warfare will make them overly large, overpriced, and ineffective. Future assessments of requirements—the mix of ships, single-mission versus multimission capability, and trade-offs of capability versus cost—must start by modifying current practices.
The U.S. Navy should consider procuring a number of small combatants that are optimized for littoral warfare. Our present and future warriors—who must go in harm’s way in shallow, cluttered, inshore battle environments—deserve no less.
Mr. Brower is president and founder of Spectrum Associates. An internationally recognized defense analyst, he has conducted comparative studies of U.S. and foreign warships, submarines, and weapon systems and is author of numerous technical reports and articles.
Captain Kehoe, well known for his work in comparative engineering analyses of U.S. and foreign warship design practices, has been associated with Spectrum Associates since his retirement from the Navy. While on active duty, he served at the Naval Sea Systems Command, as a commander of a destroyer, and as engineering officer of an aircraft carrier.