September 2014

The Amphibious Combat Vehicle

The time for expeditionary protected mobility ashore is now
Volume 98, Issue 9

LtCol J.C. Lewis

Maj Trevor Howell, USMCR
The LCAC has proven its versatility.
Photo courtesy of Department of Defense.

The Marine Corps has a long and successful history of innovation with regard to tactics, techniques, and procedures, especially when it comes to amphibious operations. This history of innovation led to the development of amphibious operations between World Wars I and II, despite many naysayers who pointed to the disastrous Gallipoli operation of 1915. The highly successful amphibious operations conducted during World War II and Korea made this type of operation a Service-defining capability for the Marine Corps. It is what truly sets the Corps apart from other Services and has shaped capability development for the Marine Corps since that time.

The history of innovation and adherence to the requirements for the conduct of amphibious operations have driven the desire for new, better, and faster means of getting from ship to shore. In support of the Ship-to-Objective Maneuver (STOM) concept, a three-legged stool was envisioned to give the Marine Corps this enhanced capability. Two of the legs have been built with the development of the MV–22 Osprey for deep vertical envelopment, and the LCAC for the high-speed connector to bring non-self-deploying fighting vehicles ashore. The difficulty has always come with the third leg: the replacement for the assault amphibious vehicle (AAV).

The Pursuit of HWS

Since the late 1970s in particular, the Marine Corps has pursued a high water speed (HWS) replacement for the AAV. There have been four separate attempts at developing such a vehicle, but the size, complexity, and high cost of the vehicle have caused it to be cancelled each time. The third attempt was the program to develop the expeditionary fighting vehicle (EFV), and though it got the farthest along, it was canceled in 2012 for the reasons cited above.

When the EFV program was canceled in 2012, the Amphibious Capabilities Working Group was established to examine the environment in which the Marine Corps would conduct future amphibious operations. Significant concerns were raised with regard to potential adversary intelligence, surveillance, and reconnaissance capabilities, as well as antiaccess/area denial (A2/AD) weapons for ships, landing craft, vehicles, and aircraft. As A2/AD technology became cheaper, more effective, and capable of greater ranges of employment, the need to expand the scope, speed, and duration of shaping operations grew. This, along with the increased need for littoral maneuver, drove the requirement for a “family of systems” approach to conducting amphibious operations from ranges greater than the originally envisioned 12 to 25 nautical miles. This is not to say that amphibious operations would be conducted from ranges greater than 25 nautical miles; rather, the Marine Corps needs greater operational reach from the seabase, either independently or as part of a joint/coalition force, to conduct shaping operations from extended ranges, at least until the effectiveness of the adversary’s A2/AD network is reduced enough to allow amphibious ships to close the distance for the remainder of the Marine forces to transition ashore.

As this group was reporting its findings during the summer of 2012, it was determined that a fourth look at the technical feasibility of an HWS amphibious vehicle was needed. Soon thereafter, Marine Corps Systems Command established the HWS Study Office. Through a great deal of study and negotiation with industry, it was proven that an HWS vehicle is technically feasible, but there would need to be tradeoffs in capability to enable high water speed. These tradeoffs included less armor (to keep below a certain weight to allow the vehicle to get up on plane), reduced operational reliability (due to complex hydraulics to transition the vehicle to and from HWS configuration and the nature of tracked vehicles in general), reduced protection from improvised explosive devices (tracked vehicles inherently have lower ground clearance, flat bottoms, and vertical sides), and less lethality (due to weight considerations). In addition, HWS can only be maintained by the vehicle in water deeper than 5 meters. Once the water depth is less than 5 meters (this distance from shore varies significantly throughout the world), the HWS vehicle must transition to low water speed by retracting its flaps and bow ramp and then lowering its tracks. Once this is accomplished, it swims the remaining distance at about the same speed as an AAV. All of these capability tradeoffs would put our Marines at risk once ashore and were deemed unacceptable.

Mitigating Capability Tradeoffs

In 2008 the Marine Corps began the development of the Marine personnel carrier (MPC) that was intended to be a complementary capability to the AAV and, subsequently, the EFV. It was designed and developed specifically to operate ashore with better armored protection, mobility equal to the M1A1, and the ability to swim from shore to shore for river crossing operations. A technology demonstrator was built at the Nevada Automotive Test Center near Carson City, NV, that proved all of the requirements could be satisfied. Industry closely followed the developments with the MPC and some competitors had prototypes already in service with foreign militaries or developed new designs to meet the requirements for the MPC. Despite this progress, in 2012 the MPC program was suspended due to the increasingly constrained fiscal environment and in favor of acquiring the joint light tactical vehicle and an amphibious combat vehicle (ACV) that would be used to replace the AAV.

A Revised Tracked vs. Wheeled Technology Comparison

The need to replace the Service-defining capability of transitioning from ship to shore and conducting forcible entry and surface assault is unquestioned. In 2013, as the debate regarding the HWS vehicle was occurring and as the AAV fleet was exceeding 40 years in age and experiencing significant obsolescence and maintenance issues, the MPC program was reconsidered as a potential solution set to hedge against the potential that tradeoffs for an HWS vehicle would prove to be unacceptable again. As the Marine Corps reviewed the MPC program, it was found that the prototypes developed by industry had significantly better swimming capability than was originally required by the MPC program. It remains to be seen just how capable each prototype can be, but initial indications are that some may be as good as the legacy AAV. In addition, the wheeled MPC prototypes provide increased reliability, higher ground clearances, V-shaped hulls, independent suspensions, and capabilities such as wheels designed to be blown off yet retain enough residual mobility to drive out of danger areas all provide a greater degree of overall force protection, better on- and off-road travel characteristics, and increased fuel efficiency over tracked vehicles such as the AAV and EFV. There also exists the strong possibility of having different weapons variants developed for additional flexibility and lethality. Moreover, it is expected that the cost of a wheeled vehicle will be less than half the cost of an HWS tracked vehicle.

Naturally, moving away from tracked technology in favor of wheeled technology for the ACV has caused some significant concern. Much of this concern revolves around the cross-country performance, especially in deep mud or soft sand, of wheeled versus tracked vehicles and the historic fact that tracked vehicles have always been able to climb over and/or cross obstacles much better than any wheeled vehicle. Because commercial industry is heavily reliant on wheeled versus tracked vehicles, even in difficult terrain, it has continued to develop better technology in this area, making considerable advances while tracked technology has remained essentially the same since World War II. When another look was taken at the MPC program, in addition to the benefits mentioned in the paragraph above, it was found that wheeled vehicles have substantially closed the maneuverability gap that previously existed between tracked and wheeled vehicles. The MPC Technology Demonstrator uses “in-line” drive technology that enables all four wheels on each side to pull together in much the same way that a tracked vehicle’s does. Combined with a higher ground clearance and the central tire inflation system currently in use in the medium tactical vehicle replacement (MTVR), the wheeled variants have equal or better maneuverability than the M1A1 and are much more maneuverable than the AAV. This has been amply demonstrated in testing.

An Analysis-Based, Phased Approach to the Solution

Based on the analysis indicated above that included lessons learned from Iraq and Afghanistan, coupled with the anticipated demands of the future operating environment, the Commandant decided to forgo an HWS vehicle for the present and to fulfill, at least initially, the ACV requirement with wheeled combat vehicles. As a result, the MPC program was redesignated as the ACV program. In addition, and as a bridge to the now wheeled ACV which could be introduced into the Operating Forces as early as the fourth quarter of fiscal year 2019 (FY19) (whereas an HWS ACV could be introduced no earlier than FY22 to FY26), the decision has been made to sustain and upgrade about a third of the AAV fleet to retain our forcible entry capability. This program will start in FY19, though some aspects such as electrical and communications system upgrades are already being addressed. Lastly, because HWS capability is still very much a requirement, the Marine Corps will continue the research and development to pursue technology that may enable this capability without unacceptable tradeoffs.

The Wheeled ACV

The wheeled ACV is an advanced generation, eight-wheeled, armored personnel carrier with a number of significant advantages. The ACV is inherently expeditionary in that its design permits it to deploy on the full range of amphibious shipping, maritime prepositioning squadron vessels, Military Sealift Command ships, ship-to-shore connectors such as the LCAC and landing craft utility (LCU), as well as inter- and intratheater transportation. As its name implies, the ACV is amphibious, and though its ability to self-deploy and recover aboard amphibious ships and swim ashore like the AAV needs to be operationally tested and proved, once ashore it provides Marines MRAP-like protection against armor-piercing direct fire threats up to heavy machineguns, indirect high-explosive fragmentation, land mines, and improvised explosive devices. Essential elements in these capabilities include protection-related technologies such as fire suppression systems, mine blast–protective seats, and protected fuel systems.

Regarding its operational capability once ashore, the ACV’s cross-country mobility is comparable to the M1A1 tank, but its high-speed onroad mobility also allows it to maneuver with other wheeled assets like the joint light tactical vehicle and light armored vehicle. The ACV is equipped with a stabilized M2 heavy machinegun in a remote weapons system, with the potential to accommodate a dual-mount, stabilized Mark 19 and M2 remote weapons system before being introduced to the Operating Forces. This will permit the ACV to engage threats on water or land with accurate fires while on the move with the gunner remaining under armored protection inside the vehicle. In addition, the possibility that different weapons variants can be developed for the ACV is very promising since this is already being done in foreign militaries. The ACV carries three crewmen (driver, gunner, and vehicle commander) and between 10 and 13 combat-loaded infantrymen with up to 2 days of supply. Two ACVs will provide transport for a reinforced rifle squad and will provide the squad leader with an additional maneuver element that can provide precision suppressive fires in support of an attack or when occupying the defense. These attributes are particularly noteworthy and make the ACV optimized to operate ashore, where the majority of the mission profile for this vehicle exists.

Near-Term HWS via Complementary Connectors

Coupled with the decision to pursue a wheeled vehicle, the decision was made to achieve HWS in the near term by a significantly increased focus on connectors. Connectors will get the ACV as close to shore as the threat will allow and achieve it much faster than tracked vehicles would be able to do swimming on their own. This means an increased reliance on LCACs in particular (capable of carrying 2 ACVs and achieving over 40 knots), but also reliance on a new vessel that is only now coming on line—the joint high-speed vessel (JHSV). The JHSV is a catamaran-configured, medium-sized vessel capable of carrying 20 to 21 ACVs 1,200 miles at 35 knots. The USNS Spearhead (JHSV 1) is the first vessel in its class (out of 10 intended to be built), and recently sailed on its first operational deployment to determine the different ways that this vessel can be employed. For both the LCACs and JHSVs, since neither can land vehicles directly ashore in a nonpermissive environment, the intent is for these platforms to maneuver quickly from well beyond the threat envelope for antiship missiles to just outside of small arms range of the shore and conduct an in-stream launch of the ACVs so that they can swim ashore on their own and deal with any threat encountered. This would complement the A2/AD fight being conducted by the amphibious task force during amphibious operations and help to enable the amphibious task force’s ability to approach much closer (ideally to within 12 miles) to maneuver the rest of the force ashore.

This increased reliance on connectors also means an increase in connector interface and maintenance capacity to support amphibious operations for a major contingency. One way to help meet this new requirement is to leverage a new class of ships coming on line. This new class of ships is the mobile landing platform (MLP), essentially an oil tanker converted into a float-on, float-off vessel that’s able to ballast to a depth necessary to enable three LCACs to operate from it at one time. The MLP is designed to come alongside selected maritime prepositioning ships and other strategic sealift ships and transfer equipment from ships to LCACs, JHSVs, and potentially other landing craft and lighterage. Vehicles and equipment will move between sealift ships and the MLP via connecting ramps and then will traverse the MLP and load onto LCACs and JHSVs for movement ashore. Additionally, a concept is being fleshed out to use heavy-lift barge carriers already in the strategic sealift inventory as LCAC “mother ships” that would enable additional LCACs to be positioned and maintained in the area of operations without taking up amphibious ship well deck spots and MLP landing spots.

What has been stated above is only the beginning. During March of this year, the Connector Summit was conducted at Marine Corps Base Quantico to see what else might satisfy the HWS requirement. Aside from the LCAC replacement program that will result in replacing old LCACs with a similar capability starting around FY17, a replacement program for the venerable LCU is also getting started. In addition to these standard programs, other interesting concepts were presented at the summit that might prove useful. These include an ultra-heavy-lift amphibious connecter which is designed to lift as much as an LCU and go about two-thirds the speed of the LCAC. A half-scale model has been built and is being tested in Hawaii. An LCU-Folding concept may prove to carry 3 to 4 ACVs and achieve speeds of 19 to 20 knots. The most interesting concept presented was something the Marine Corps actually tested in the late 1980s to be used by light armored vehicles to get ashore quickly: a self-propelled aluminum sled that accommodates one vehicle. The driver of the vehicle controls the sled and steers it ashore at speeds up to 25 knots. Once ashore, the vehicle drives off the sled and leaves it for landing support units to police up and return to seabased shipping. These concepts will take several years to get to a technology level that can then be pursued, but all represent different ways to achieve the HWS requirement.


Littoral operations require a diverse array of complementary capabilities that enable amphibious forces to maneuver along coastlines, in interior waterways, and from ship to shore. As discussed in Expeditionary Force 21, the Marine Corps intends to employ a combination of capabilities to meet these requirements. This family of systems has been described above, and though some aspects are developmental, the overall approach is one of finding different ways to achieve the requirement to get from ship to shore as quickly as possible and fight once there. In particular, it is believed that the ACV optimizes operations within the littorals by providing commanders a capability that can operate from naval platforms while striking a balance between being light enough to facilitate rapid deployment and heavy enough to conduct sustained expeditionary warfare across the range of military operations while providing armored protected lift for our ground forces. The ACV provides our Marines with ship-to-shore maneuver as well as significantly enhanced protection, mobility, and possibly even lethality, all of which are essential to conducting operations in the current and anticipated operating environment. In the aggregate, these efforts will significantly advance the Marine Corps’ ability to conduct operational maneuver from the sea and ship-to-objective maneuver in the 21st century.

LtGen Glueck is the Deputy Commandant, Combat Development and Integration and the CG, MCCDC.