The EFV, designed by General Dynamics Land Systems, is an amphibious armored tracked vehicle with an aluminum hull. The engine is a custom MTU Friedrichshafen diesel (MT883) with two modes of operation; a high power mode for planing over the sea, and a low power mode for land travel. It has a crew of three and can transport 17 Marines and their equipment. The EFV is the first heavy tactical vehicle with a space frame structure.
The hull has a hydraulically actuated bow flap to aid planing with a maximum waterborne speed of 46 kilometres per hour (29 mph; 25 kn). Shrouded Honeywell waterjet propulsors are integrated into each side of the hull, which create over 2,800 horsepower. It is also outfitted with hydraulically actuated chines to cover the tracks while in seafaring mode. The rear loading ramp is not able to open while the vehicle is afloat, typical of other swimming military ground vehicles.
The vehicle uses an Ethernet network connected by the Tactical Switch Router, based on the COTS DuraMAR Mobile IP router for its internal and external communications.
The electronically powered two-man MK46 turret on the personnel variant accommodates the commander on the right and gunner on the left, a fire control system, and the main and coaxial weapons.
The standard version has a Mk44 Bushmaster II 30 mm cannon, which fires up to 250 rounds per minute with single, burst, and fully automatic capabilities up to 2,000 metres (2,200 yd) in all weather conditions. A general purpose M240 7.62 mm machine gun with 600 rounds of ready-to-use ammunition is mounted coaxially with the main gun.
EFVP1 engineering prototype undergoing shock testing
The EFV is fitted with composite armor, mine-blast protection, and a nuclear, biological and chemical defense system. The aluminum hull has caused some concern due to protection issues. However, aluminum hulls have been used for decades in military ground vehicles and watercraft.
In June 2007 members of the House Armed Services Subcommittee on Seapower and Expeditionary Forces sent a letter to the Commandant of the Marine Corps urging that the EFV be redesigned to give troops better protection against roadside bombs. The Marines have suggested that underbelly armor appliqué could be applied after the EFVs come ashore and before they encounter IEDs. The limited protection the EFV offers is an improvement on that offered by the AAV so the replacement is an advantage, given the current doctrine of using landing craft for land patrols.
However, tests in January and February 2010 at Aberdeen Test Center demonstrated that the EFV offers blast protection equal to a category-2 Mine Resistant Ambush Protected vehicle, including two simulated improvised explosive devices under its belly and tracks. Tests also show that it has superior protection from direct and indirect fire. The flat hull, which has endured persistent criticism for not being the more blast-resistant V-shape, is necessary for the EFV to plane across the surface of the water and reach its high speed, while dealing with sea states of Category 4.
On 13 October 2010 the Navy awarded M Cubed Technologies a contract to develop new armor for the EFV to offer better protection and lighter weight.
Given the increasing ranges of shore launched anti-ship missiles, the EFV’s 25 nautical miles (29 mi; 46 km) range for amphibious landing may no longer provide the anticipated protection predicted for an over the horizon launch. The U.S. Navy has been reconsidering the over the horizon approach, and is considering 10–18 miles appropriate for amphibious launches. This shift in doctrine has made the EFV’s high water speeds less necessary. The EFV’s need for high water speed has resulted in an engine that is 1,200 hp more powerful than the M1 Abrams, even though the EFV weighs far less.