and their equipment. The EFV would have been the first heavy tactical vehicle with a space frame structure. The hull had a hydraulically actuated bow flap to aid planing with a maximum waterborne speed of . Shrouded Honeywell waterjet propulsors are integrated into each side of the hull, which create over of thrust. It was also outfitted with hydraulically actuated chines to cover the tracks while in seafaring mode. 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. Armament The electrically powered two-man MK46 turret on the personnel variant accommodated the commander on the right and gunner on the left, a fire control system, and the main and coaxial weapons. The standard version was to have had a Mk44 Bushmaster II 30 mm cannon, which fired up to 250 rounds per minute with single, burst, and fully automatic capabilities up to in all weather conditions. A general purpose M240 7.62 mm machine gun with 600 rounds of ready-to-use ammunition was to be mounted coaxially with the main gun. Countermeasures The EFV was fitted with composite armor, mine-blast protection, and a nuclear, biological and chemical defense system. Although aluminum hulls have been used for decades in military ground vehicles and watercraft, they have caused some concern due to protection issues. 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 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, was necessary for the EFV to plane across the surface of the water and reach its high