The Spearhead-class expeditionary fast transport (EPF) is a United States Navyâ€“led shipbuilding program to provide “a platform intended to support users in the Department of the Navy and Department of the Army. The Expeditionary Fast Transport (EPF) program is a cooperative effort for a high-speed, shallow draft vessel intended for rapid intratheater transport of medium-sized cargo payloads. The EPF will reach speeds of 35â€“45 knots (65â€“83 km/h; 40â€“52 mph) and will allow for the rapid transit and deployment of conventional or special forces as well as equipment and supplies.” The vessels are a part of Military Sealift Command’s Sealift Program. The class was previously designated as “Joint High Speed Vessel (JHSV)”, but was changed in September 2015.
The EPF is able to transport U.S. Army and U.S. Marine Corps company-sized units with their vehicles, or reconfigurable to become a troop transport for an infantry battalion. The EPF has a flight deck for helicopters and a load ramp that will allow vehicles to quickly drive on and off the ship. The ramp is suitable for the types of austere piers and quay walls common in developing countries. EPF has a shallow draft (under 15 feet (4.6 m)). The EPF is an aluminum twin-hull catamaran shell containing four diesel engines, rudimentary control facilities for up to 40 crewmembers, and 312 airline-style passenger seats, along with an expansive flight deck on the top.
The rest of the vessel is a convertible 20,000 sq ft (1,900 m2) mission bay that can be loaded to carry whatever cargo is needed. Vehicles and cargo are loaded and unloaded by a ramp that can support up to 100 tons of weight. Although designed for a military crew of 46, the ships usually have a crew of just 26 mariners. The passenger room contains reclining seats with overhead televisions and racks for weapons and equipment. A vessel has 104 permanent berthing spaces. Without resupply, it can support 312 embarked personnel for four days, or 104 personnel for 14 days. The EPF has a greater level of comfort for the crew than larger Navy ships. The stateroom-style berthing areas for the ship’s crew have private features like toilet stalls, outlets, air conditioning, and even thermostats.
One disadvantage of the ship’s design is instability in rough seas and at high speeds. At 10 knots in calm sea states, the hull can roll up to four degrees to each side, while conventional ships would roll very little, which would increase if the ship goes faster in rougher conditions, raising the possibility of seasickness. To achieve its top speed, the ship has to be traveling in waters not exceeding sea state 3 (waves up to 1.25 m (4.1 ft) high). At sea state 4 it can travel up to 15 knots, travel only 5 knots in sea state 5, and has to hold position in any sea state higher; while this might be seen as an operational limitation that can delay its arrival to port facilities, the ship was intended to operate closer to shore rather than in blue-water conditions.