Tag Archives: corvette

Sea Control 11: Sand Pebbles

Sea-ControlMatt, Chris, and Grant are joined by Scott Cheney-Peters for a CIMSEC party on the China ADIZ, corvettes, procurement, and Iran. Grant checks out because he’s has a sub-par phone, Scott takes frequent naps due to a Turkey overdose. Remember to subscribe to us on iTunes, Xbox Music, and Stitcher Stream Radio. Without further ado, here is Sea Control 11: Sand Pebbles.

Also, as promised in the podcast, a link to some international law-y goodness: “Limits in the Seas, No. 114.”

Cheaper Corvettes: COOP and STUFT like that

If the answer to the Navy’s future is robotics, then Admiral Greenert’s July 2012 U.S. Naval Institute Proceedings piece, “Payloads Over Platforms, Charting a New Course” opens up a whole new world of possibilities for using existing small ship platforms as “trucks” to deliver large numbers of modern weapons platforms to areas of interest.

As former Under Secretary of the Navy Bob Work emphasized during his recent appearance on MIDRATS,  the Littoral Combat Ship is such a truck–a vehicle for delivering unmanned weapons system.

This post is meant to take that concept and cheapen it.

What is a corvette? Something smaller than frigate but larger than a patrol boat, I guess. The LCS in either of its variants is large at about 380 feet in length and displacing 2800 tons. A Gearing-class destroyer from post WWII measured in 390 feet and 3400 tons.  The Perry-class frigates are over 440 feet and 4100 tons.

Seems we have a lot of size and space to play with.

It occurs to me that we need to take the thinking that developed the WWII escort aircraft carrier (CVE) and model it down to a ship that is a “drone” carrier (and by “drone” I mean unmanned vessels of any type- surface, subsurface and aerial) – like the LCS only in the smaller economy version.

After all, if the real weapons systems toted by the LCS are its drones, then virtually any vessel capable of lowering said drones into the water or into the air and hosting their command and control system can be a “drone carrier,” too. Such a ship becomes a “mother ship” for the drones.

Are drone carriers are really “war ships?”  Remember, “payload over platform.”

Suppose we take a hull like an offshore oil platform supply “boats”  outfitted with a “surface warfare module” (yes, like that designed for the LCS) and four davits designed to lower four USVs into the water.

If the USVs are outfitted with torpedoes or missiles like those discussed here, and if you deploy them in the face of a threat, you now have a ship with capable weapons systems out there.

Other vessels might include large tuna clippers and small freighters.

Photo: San Diego Tuna Clipper (they already have a stern launch system)

Even better, you have now added complications to the targeting systems of any opponent because instead of having one vessel to engage, it now has five. Make up a small squadron of such mother ships (say 4 per squadron) and your opponent now faces 20 vessels.  These may consist of multiple threats- a squadron may have USVs in combinations of missiles, torpedoes or other weapons.

If the mother ships carry additional drones, the threat increases as each batch is placed in the water. Proper use of an aerial relay drone may allow the mother ships to be reasonably far from the action site, under the umbrella of a larger warship or some sort of converted floating offshore oil platform configured properly to “sea base” operations.

The drone mother ships will require a tender of some sort for fuel and other hotel services, but such a tender need not be elaborate nor expensive. Under the proper circumstances they might be shore supported.

One of the cost-saving features of this concept is that the drone mother ships might be acquired in a COTS fashion either by lease or purchase. Under an old U.S. Navy program (and one used by the Australians), there is precedent for using a “Craft of Opportunity Program (COOP)” to acquire vessels to experiment with. While the U.S. experience with COOP involved inshore mine hunting, the underlying concept is sound–lease or buy already built units that can meet the minimal standards of your “drone trucks”–and avoid the expense and delays of design and construction (albeit allowing for necessary modifications) .  The other expression for acquiring such ships is “STUFT”-“Ships Taken Up From Trade,” which the Royal Navy used to put together a force during the Falkland War in 1982.

These vessels can be minimally manned and are, in the famous phrase “expendable.” Since they deliver their weapons remotely, speed is not really an issue. Instead, deck space and electrical capacity will be important. Manning could be mixed CIVMAR, active and reserve Navy.

For example, an older diesel powered platform supply vessel capable of 12 knots and about 290 feet in length could work if properly outfitted. I suspect it, even with the appropriate modifications will not cost any close to even a cheap non-truck warship. Heavy lift a half dozen of these to where they are needed and you have a force multiplier on the cheap. Lots of deck space for vans, generators and cranes and perhaps even some self-protection bolt-ons.

Are they “corvettes?” Payload-wise they could be . . .

Of course, unlike a “standard” corvette but like the LCS, these drone carriers are dependent on modules.

Eagle1 is the nom de plume for Mark Tempest, who maintains his own blog EagleSpeak and co-hosts the popular Naval Affairs podcast “Midrats.” Mark is a retired attorney and former US Naval Reserve Captain (Surface Warfare).

Corvettes Do Not Support Global Seapower

There is a growing belief in U.S. naval circles that aircraft carriers and higher-end U.S. surface combatants are becoming vulnerable to attacks by improved cruise missiles and targetable ballistic missiles such as the DF-21D. Proponents of this belief argue that corvette-sized vessels grouped in flotillas cost less, are more survivable than larger vessels and (somewhat darkly) suggest that U.S. national command authority would be less adverse to losing a few corvettes in combat than they would to the loss of a “capital ship” Arleigh Burke class destroyer. In reality, smaller ships have their own set of weaknesses that makes them no more effective than larger combatants. The littoral combatant ship (LCS) is capable of all of the peacetime and most of the wartime abilities of the corvette. Most importantly, the geography of 21st century seapower does not lend itself to low endurance vessels dependent upon isolated fixed bases for support. It may be useful to build and test a small flotilla of such craft as a proof of concept operation, but the U.S. should not build a large number of corvettes (and repeat the mistakes of the LCS program), until a full program of test and evaluation is complete. Even then, the U.S. should be wary of putting so much of its at-sea striking power in such a short-ranged, vulnerable class of ship.

DN-ST-93-05725Corvettes have their own “laundry list” of shortcomings that make them undesirable as a replacement for a large part of the current surface fleet. Past missile corvettes have been employed by less powerful navies as low-cost, short range coastal defense units. These craft enjoy interior lines of communication and supply, and are an ideal component to a coastal nation’s anti-access/area denial (A2AD) capability. U.S. corvette advocates however desire to use them in an offensive role on the high seas. Such an flotilla would be dependent on network information for both offensive and defensive operations. In the years since the First Gulf War in 1991, the U.S. has made it very clear to any of its potential opponents that it is very reliant on military networks to achieve its desired military objectives. No peer or near-peer opponent is likely to allow the U.S. unimpeded use of its military networks and will likely targets those systems in its own first attacks. Without network connectivity, corvette forces would be dependent on their own short-range sensors for targeting data and would need to move dangerously close to prospective targets in order to attack. The U.S. is still dependent on the 1970’s vintage Harpoon subsonic anti-ship cruise missile (ASCM) as the likely armament of a missile corvette. Longer range supersonic weapons would need to be developed and fielded in order to make the ship a “battle-worthy” opponent. Failure to do so would create another fiasco like the LCS where key mission components significantly lag behind the construction of the actual ship. Unlike higher-end U.S. combatants, corvettes do not have area defense weapons nor are their weapon systems self supporting. If attacked, rather than a networked defense, each corvette must individually engage incoming threats. Such actions, if uncoordinated and done in close proximity to other ships can have disastrous results. In the 1982 Falklands war, there were cases of ASCM’s decoyed away from one ship that suddenly engaged another without time for response. A corvette is also much more likely to be destroyed with all hands than a larger U.S. surface combatant if hit by even one medium-sized cruise missile. Each such corvette has a crew of between 35 and 40 highly trained personnel who would likely be lost. If the U.S. Navy really does value its well-trained personnel more highly than individual ships, it will not assign them to corvettes likely to be sunk. “They Were Expendable” makes for a good movie title, but U.S. naval personnel in the 21st century are not such a disposable commodity.

Supporters of the corvette claim that the ships can fulfill many peacetime duties including presence functions and training with allied naval forces. The LCS, which is already under construction and in the process of fleet introduction, is already capable of such activities. LCS is also a fully deployable warship capable of sustained operations at sea for at least 21 days. A force of corvettes however has only an 8-day sustainability at sea and would require a significant advanced base from which to resupply and refuel. If the recent behavior of even a close U.S. ally as Japan is any example, few nations would desire a large U.S. military presence necessary to support a large number of corvettes. The LCS can be supported through refueling and resupply at sea via underway replenishment. Since the LCS is already planned for procurement in large numbers, why duplicate its capability with another class of ship?

Finally, the geography of seapower as understood by maritime nations with global interests such as the United States does not support the use of such short-ranged vessels as corvettes. Such a nation must be ready to transfer large parts of its armed forces seamlessly over great distances. Relatively high-speed, long range naval units capable of global deployment are the best solution to the problem of geography. Corvettes can be moved from one part of the globe to another but neither with the speed nor cost effectiveness of larger platforms with better endurance. The fleet of a global power must be able to depart from one location, sail thousands of miles if necessary, arrive in theater and attain sea control without reliance on forward land bases which may be vulnerable or unavailable for use.

A small force of corvettes as a proof of concept test may be useful, but in the current constrained fiscal environment, the first priority of the Navy must remain high-endurance vessels capable of extended combat operations at sea without forward base support. A large force of corvettes cannot meet this requirement. If required in a wartime scenario, corvettes can be procured and rapidly fielded in large numbers. The U.S. is a maritime nation with an interest in protecting and securing what political scientist Barry Posen called the “global commons” of oceanic trade routes. Global power projection requires globally deployable naval units rather than regionally dependent corvettes.

Steve Wills is a retired surface warfare officer and a PhD student in military history at Ohio University. His focus areas are modern U.S. naval and military reorganization efforts and British naval strategy and policy from 1889-1941. He posts here at CIMSEC, sailorbob.com and at informationdissemination.org under the pen name of “Lazarus”.

Corvette: What Is It And Why Does It Exist?

The question posed in the title is trivial but without an obvious answer. The term corvette originally appeared in 17th-century French Navy documents. It defined corvettes as simply ships smaller than frigates, a definition that has survived until today. This class of ship is defined only by size.
flower_class_corvetteDuring interwar periods in different countries similar ships were called sloops, gunboats, or avisos. At the outbreak of WWII, the name corvette was revived by the British Royal Navy for a class designed to meet a pressing need for cheap and mass produced ASW escorts. As a result, a design based on a whale catcher became probably the most famous corvette type, the Flower class, the hero of Nicholas Monserrat’s novel Cruel Sea.
In 2004, a team of NATO naval specialist worked on a paper entitled, Small Ship Design.  This document brought additional distinctions in ship classification and made an important difference between Offshore Patrol Vessels and Small Littoral Combatanst. The first optimizes its weight and volume for endurance, presence and low-cost, the latter for combat-related payload and survivability. It is important, however, to note that we observe many designs that we can call “hybrid”, either up-armed OPVs with some naval standards implemented to enhance survivability or lightly armed combatants sometimes classified as patrol corvettes or patrol frigates. The resulting designs can be better understood after a reading of D.K. Brown’s discussion of ship’s design philosophy in his book The Future British Surface Fleet: Options for Medium-sized Navies. The author describes the story of Type 23 Duke frigates, initially intended to be relatively small ships that could tow a sonar array:

“The ship envisaged was too expensive to be expendable, and yet was unable to defend itself. The whole concept was therefore philosophically “unstable,” and had to shrink to a cost level at which its loss could be accepted, or grow to a cost of over 100 million pounds in order to allow for some defensive armament.”

It seems that corvettes as opposed to OPV are dangerously close to above mentioned “unstable” zone. corvettes and other “flotilla” ships also suffer from attitudes driven by axioms of modern management. In peacetime, with only limited means available, we prioritize goals and focus on the seemingly more important “battle-force” rather than the “flotilla.” The latter falls into the “would be nice to have” category, but this changes in wartime. Vincent P. O’Hara, W. David Dickson, and Richard Worth in their book On Seas Contested illustrate wartime construction efforts during WWII made by major players by showing the number of ships built during the war, by category. This data, supplemented by a simple web search, and presented in a slightly different form makes visible how small combatants grow in number.

Why do corvettes exists at all? It seems appropriate to ask such a question if the whole class definition is based on size only. An attempt to make a generalization could be a statement that for the big navies of naval powers, corvettes fulfill some niche, specialized roles like coastal ASW, patrolling or even mine warfare, while for small navies or land powers they tend to be a capital ship. For a big navy they promise relatively low costs and hi numbers of hulls. Strict control of specifications and requirements as well as resigning from everything not related to the planned main function of the ship are essential to keep their costs within the budget. On an opposite side of spectrum, a small navy would be driven by the desire to install more powerful sensors and armament. Seakeeping and endurance could be of interest as well. The problem is that any efforts to turn these small combatants into multi-mission ships pushes them towards “unstable” zone of design.

The weakest point of corvettes seems to be their air-defense capabilit,y limited typically to self-defense. This means that at least in theory corvettes are rather easy to destroy by cruise missiles or even direct munitions dropped by aircraft. To overcome this limitation corvettes need to operate under the cover of battle-force or shore based defensive systems. They could also use tactics known from the Cold War’s “Outer Air Battle”, aiming to kill the shooter, not the arrow. Cruise missiles give corvettes disproportionate power to their size, but to use such weapons effectively, information superiority is a necessary and the best defense. Another problem that quickly emerges is the number of munitions at their disposal and how effective they are. Helicopters and/or armed UAVs are valuable assets for corvettes adding both to firepower and information superiority. Yet another road is to seek support from technology. One good example is the Swedish Visby corvette designed with the motto Invisible, not Invincible, another is the CAMM missile, which offers mid-course guidance independently from radar thus promising local area air defense for ships smaller than frigate. Or as already mentioned unmanned vehicles are another way technology can provide an edge.

The variety of tasks or functions flotilla ships like corvettes can fulfill is very large and quite often not anticipated before as shown by below excerpt from Wikipedia description of the Royal Australian Navy’s HMAS Bathurst: 

“The two main purposes the ships were intended for were minesweeping and anti-submarine escort. However, the corvettes found themselves performing a wide range of duties, including troop and supply transport, bombardment, assault landings support, survey and hydrography mapping, and providing aid to disabled ships.”

So what to do with a ship so broadly defined, surprisingly useful in wartime, and in permanent tension between value and performance? If we take a look once more again on Sir Julian Corbett typical forms of naval warfare…

“For clearness we may summarize the whole in tabulated analysis, thus:—

1. Methods of securing command:
(a) By obtaining a decision.
(b) By blockade.

2. Methods of disputing command:
(a) Principle of “the fleet in being.”
(b) Minor counter-attacks.

3. Methods of exercising command:
(a) Defence against invasion.
(b) Attack and defence of commerce.
(c) Attack, defence, and support of military expeditions.”

Corvettes can participate in all of these. It just depends on few factors like whether the navy possesses preponderance over the enemy, or is acting independently or as a part of coalition forces. A small navy facing a dominating enemy can still conduct minor counterattacks, but under the cover of an allied battle-force it can switch to attacking  or defense of commerce or a blockade. Even decisive battle is conceivable if the enemy fleet is an equally small peer navy. Although not really a homogenous class of ships, corvettes and similar small ships will most probably continue to be popular and in demand and will surprise us by their versatility.


Przemek Krajewski alias Viribus Unitis is a blogger In Poland.  His area of interest is the context, purpose, and structure of navies – and promoting discussion on these subjects in his country.