The Case for an Expeditionary Frigate

By Captain Gordan E. Van Hook, U.S. Navy (Retired)

In his direction to the Navy, Secretary Hagel has envisioned the new SSC to have characteristics “generally consistent with the capabilities of a frigate.” 3 As compared to the current LCS variants, this has been interpreted to mean that the SSC will generally be a larger, heavier-armed, and more robust warship, between an LCS and an Arleigh Burke –class guided-missile destroyer in size. In terms of tonnage, this would place candidate designs within the range of 4,000 to 9,000 displacement tons. The Navy’s RFI made it clear that it was seeking mature designs, including redesigns of the current LCS. Understanding that the Navy cannot afford additional training and maintenance pipelines, competitive designs will likely also need to accommodate or support existing or very similar weapons; sensors; and command, control, communications, computers, and intelligence equipment as are currently found in the Fleet.

Increased Lethality

An expeditionary frigate should be expected to go into harm’s way and toe-to-toe in littoral waters with any likely surface competitor of a similar size, attacking aircraft, or quiet diesel submarines. The current LCS variants as well as the national security cutter could each be upgraded to provide increased lethality. This could include “up-gunning” from the current 57-mm gun to a 76-mm gun; modules included for the Evolved Sea Sparrow missile or even standard missile (SM-2 or SM-6) air-defense missiles; an advanced phased-array radar such as SPY-1F, a smaller export version of the Aegis radar; and inclusion of the Harpoon II or a similar antisurface missile. Additionally, there are several existing NATO frigates that have similar systems, such as Denmark’s Absalon and Iver Huitfeldt , Spain’s F-100, Germany’s MEKO, France and Italy’s FREMM, and Norway’s Fridtjof Nansen class.

In the current LCS designs, the U.S. Navy has placed a great emphasis on speed. However, this comes at a great cost in terms of lethality. Increased weapons and sensors dramatically increase the space and weight required, and the current high-speed LCS designs cannot support these while maintaining their speed requirement. This is an old problem in the design of warships, referred to by naval architects as “the iron triangle” of speed, payload, and endurance/range, as an improvement in one will inevitably be at the cost of the other two. Traditionally, modern frigates have been designed with sufficient armament and range at a lower top speed to perform escort and patrol missions. An expeditionary-frigate design should focus more on lethality, maneuverability, and sufficient sea-keeping to support blue-water operations if required. High speed will provide little advantage in lethality against other warships, aircraft, cruise missiles, or even small boats.


The three elements of survivability are susceptibility, the ability for a ship to defend itself; vulnerability, the effects of an initial casualty on a ship; and recoverability, the ability for a ship to conduct damage control. The current LCS variants are designed to be Level I–survivable, the lowest Navy designation, and they are generally considered inferior to the existing foreign frigates in each of these elements. The inclusion of air-defense missiles and sensors could improve their ability to defend themselves, but the ships lack the degree of compartmentalization and structural strength to significantly reduce their vulnerability and improve their recoverability. The Freedom class’s steel monohull design is generally considered superior to the Independence ’s aluminum hull and superstructure, but neither class was designed to be shock-hardened, and they are unable to survive the major damage caused by a modern cruise missile or mine. The foreign frigate designs, by contrast, have the survivability expected of warships. Already well armed to reduce susceptibility and vulnerability, they are also compartmentalized and shock-hardened, even to include chemical, biological, and radiological (CBR) zones. For example, the Danish frigates have stealth features to reduce their acoustic, radar, visual, and infrared signatures, and they are fully shock hardened and tested and incorporate separate gas-tight citadels with external wash systems for CBR defense.

Traditionally, U.S. Navy frigates have been designed to Level II survivability. A future expeditionary frigate, designed to go into harm’s way in foreign waters, should return to this standard. Foreign designs exist that, if not exactly built to Level II standards, are very close. Each existing design should be evaluated and ranked to this standard.


In the context of warship design, flexibility generally refers to the ease by which the ship can change its mission focus, as well as the number of possible missions. In the case of the LCS, flexibility largely comes in the size and capacity of their mission decks and the ability to swap mission modules. Current LCS variants will have modules to support mine warfare, antisurface warfare (principally against small boats), and antisubmarine warfare (against diesel submarines). However, it is unclear if the Navy intends to be able to change these modules in forward theaters with any speed, or how many additional mission modules are being considered.

An expeditionary frigate could certainly benefit from the inherent flexibility of an open mission deck as found in the LCS variants, and consideration should be given to even larger mission decks, such as those found in the Absalon class of Danish frigates. In the Absalon , which the Danish refer to as a “command-and-support ship,” there is an entire extra multipurpose mission deck known as a “FLEXDECK” with a stern vehicle ramp that can accommodate containerized command-and-control support and a company-sized unit of 200 men with vehicles.

Alternatively, the deck, installed gantry crane, and ramp can support mine-laying and mine-clearance equipment, a modular hospital (or a modular prison), or a load of 50 vehicles; 7 tanks; 2 landing craft, vehicle, personnel; or 2 medium-sized helicopters. Obviously, such flexibility in an expeditionary-frigate design could give combatant commanders a host of capability and mission options, especially concerning theater security cooperation and engagement with regional partner navies, coast guards, marines, and special operating forces. While all expeditionary frigates do not require a FLEXDECK, serious consideration should be given to employing such a concept in a number of the new SSCs. However, it should be noted once again that if consideration is given to a FLEXDECK concept, there may be a trade-off in considering a large topside weapons package such as SPY-1F/SM-2. A heavier weapons and sensors package would require shortening a FLEXDECK to support the increased weight.

There have also already been some U.S. Navy advances in flexible infrastructure in the USS George H. W. Bush (CVN-77) and Gerald R. Ford (CVN-78) that employ features such as standardized perimeter deck tracks and moveable stanchions and equipment racks, which could be very useful in increasing the flexibility of an expeditionary frigate. 4


Modularity is often confused with flexibility but should be thought of as a characteristic that can enhance it. It is best thought of in terms of standard packages for weapons and sensors, and most importantly standard interfaces. If the U.S. Navy incorporated such standardization in its ship design, it could achieve true flexibility in its major weapon systems and realize the power behind Chief of Naval Operations Admiral Jonathan Greenert’s vision for “payloads over platforms.” 5 Once again, the Danes have pioneered such a concept in their frigate designs using the “standard flex” or STANFLEX concept. The Royal Danish Navy had to deal with tightening budgets back in the 1980s and the need to replace aging warships in the face of future mission uncertainty. An expeditionary frigate built to a similar concept could face an uncertain future with an ability to rapidly change weapons and sensors in as little as 48 hours depending on the preeminent threats envisioned. Such modules could be stored forward afloat or ashore, or kept stateside to support ship outfitting before an overseas deployment. Current STANFLEX designs may have to be modified to support systems like SM-2, but the underlying concept remains applicable.

The other side of true modularity that could make it attractive to an expeditionary-frigate design beyond the flexibility of changing mission packages is the ease of technology refresh in a modular design. Even if a warship retains its same weapons and sensors for its entire service life, a design with common interfaces can greatly simplify the upgrade and modernization process as new models of existing systems or entirely new systems are introduced to the Fleet. Besides ease of modernization, true modularity eases maintenance and repair activity as a defective module can be swapped out rapidly with a new or reworked one.

Built-in modularity in a common design could also make an ideal candidate for foreign military sales of an expeditionary frigate to regional partners and allies. A ubiquitous common platform for an expeditionary frigate could be thought of as an “iPhone warship” where nations could choose their own “apps” in the form of common weapons and sensors tailored to fit the unique missions of their nation or region. Such a concept could bring new alternatives for interoperability and potentially new heights of global maritime cooperation and security. Mass production of a globally useful common design could allow the perfection of construction techniques and processes that could in turn enable an efficient production across multiple shipyards, driving down unit costs. With a standard platform and standard interfaces, modernization using new and evolving modules could also be achieved at a fraction of previous prices.


As stated earlier, all of the characteristics of increased lethality, survivability, flexibility, and modularity in a potential expeditionary frigate must fit under an overarching affordability. Standardization and modularity in the overall design of the ship, combined with commercial procurement built into the design and state-of-the art efficiency in processes and outfitting measures, can significantly drive down construction costs and time and lead to lower lifecycle costs. Automation and efficient layout can support optimal manning concepts and keep the required crew numbers low. Other nations like Denmark have shown that it is possible to build ships that cost less but are just as capable. The Absalon and Iver Huitfeldt classes were built for under $340 million in 2010 dollars. These mature and proven designs could easily be built in a U.S. shipyard with little or no modification.

There is no need for an expensive redesign of existing warships, and a new SSC in the form of an expeditionary frigate can be acquired at a comparable or lower cost than the current LCS. Ideally, a force of 20 new expeditionary frigates would include ten Absalon command-support ships with FLEXDECK and STANFLEX, and ten Iver Huitfeldt frigates with STANFLEX and Mk-41 VLS for standard missiles. Such a flexible force of ships would provide the U.S. Navy with a significant increase in lethality and survivability at no additional cost.

1. “Lockheed, Austal Submit Small Warship Ideas,” Maritime Executive , 22 May 2014.

2. JP 1-02, The DOD Dictionary of Military Terms , as amended through 15 March 2014.

3. DOD News Transcript, “Remarks by Secretary Hagel and Gen. Dempsey on the fiscal year 2015 budget preview in the Pentagon Briefing Room,” 14 February 2014, .

4. Michael Bosworth, “Transition Interface with Early Systems Engineering: SEALION and Open Systems Case Studies,” Brief to 13th Annual Systems Engineering Conference, 25–28 October 2010.

5. ADM Jonathan Greenert, USN, “Payloads over Platforms: Charting a New Course,” U.S. Naval Institute Proccedings , vol. 138, no. 7 (July 2012), 16–23.

Captain Van Hook is a retired surface warfare officer and is currently a maritime consultant.


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