Expeditionary Warfare Craft (E-craft)
Beachable High Speed Sea Base Connector
Knik Arm Transport Rescue Boat
Lockheed Martin Littoral Ships and Systems is currently under contract to build the Expeditionary Warfare Craft (E-craft), a beachable high-speed vessel (HSV). E-Craft (Expeditionary Craft) Sea Lifter will demonstrate the functionality of a ship that can perform expeditionary logistics support and provide a multi-purpose, cargo and troop ship that performs efficiently at high speed, in ice, and in shallow waters, including beaching, and loading and unloading heavy equipment. The vertical position of the ship's center deck and the hull buoyancy both can be adjusted while underway. It could be a player in the sea base to shore high-speed connector realm.
Lockheed Martin produced the Varicraft concept as part of its LCS research. Although not used for LCS, it received congressional interest as a transformative technology. Lockheed and non-ONR congressional funding changed Varicraft to E-Craft. This acquisition transaction for prototype (using Section 845) N00014-05-9-0001 was awarded to Alaska Ship & Drydock Inc on 22 August 2005, in the amount of $29,900,000. The estimated completion or expiration date is 30 October 2010. ONR plans to begin testing the E-Craft, to support Alaska ferry service in 2007 as a potential future capability for seabasing. E-Craft will demonstrate the functionality of a ship that is capable of performing the mission of expeditionary logistics support, providing the Navy with a high speed, multi- purpose, cargo and troop ship that can perform efficiently according at high speed, in ice, and in shallow waters.
The 193'x50' E-Craft is being built at Ketchikan's Alaska Ship & Drydock Inc. It will be owned and operated by the Matanuska-Susitna Borough. The ferry will be half scale of a future military vessel. It will carry up to 150 passengers, 20 cars and travel at 17 knots. It will operate as a civilian ferry to carry vehicles and passengers across Cook Inlet's Knik Arm near Anchorage, Alaska. Knik Arm of Cook Inlet, the mouths of the Susitna, Matanuska, and Knik Rivers, and the communities of Anchorage, Palmer, and Wasilla are the hub of "human Alaska." About 300,000 people live within 10 miles of its shores, yet Knik Arm provides habitat aplenty for area wildlife and is hardly an urban slough.
The design is a modified SWATH/catamaran that can operate in four modes: SWATH, catamaran, landing craft or rescue craft. At maximum draft (about 11'5"), it is in SWATH mode. At 8'7" draft, it is in catamaran mode, and at a draft of about 3'10", it is in barge-and-rescue mode, accomplished by adjusting the height of the floating center vehicle deck. At this minimum draft, the vessel should be able to be beached and load/unload vehicles, cargo, and passengers at the bow.
The purpose of this project is to build a prototype to test various technologies for their usefulness in employment in potential new naval ship designs to facilitate the Navy's warfighting strategy Seapower 21. The E-CRAFT will be constructed as a ferry serving as a research vessel that can be used by ONR to develop and evaluate designs and intregal leading edge technologies to demonstrate the operational utility of the vessels design in the performance of littoral transport mission.
The E-Craft will provide the Navy with a high speed, multi-purpose, cargo and troop ship. It will perform efficiently at high speed, in ice, in shallow waters and in high sea states, thus offering operational flexibility and logistic delivery efficiencies far beyond the Navy's current capability. The benefits to the Navy are the ability to assess new technologies and concepts and collect long term operational data as well as provide a potential test platform for emerging technologies in a particularly harsh and demanding environment with minimal additional cost.
Vessel hulls have traditionally been designed for specific uses, such as for use in shallow waters or in deep waters. Different hull designs provide for optimal operating characteristics for different uses. Shallow-draft vessels, for example, often have hulls that are relatively "flat" to maximize displacement and minimize draft, whereas deep-draft vessels often have v-shaped hulls that provide deep draft for desired seakeeping (e.g., good seakeeping providing low undesired motion, such as vertical motion or rocking).
More specifically, shallow-draft vessels are often designed with flat bottom hulls to provide the ability to navigate in relatively shallow waters, such as in shallow-water harbors, along rivers, along shorelines and in other bodies of shallow water. Shallow-draft vessels are also designed to maximize payload carrying capacity and to provide for simplified on-loading and off-loading of cargo. Examples of shallow-draft vessels include landing craft mechanized (LCM) and landing craft utility (LCU) that are often used by amphibious military forces to transport equipment and troops from sea to beachheads and/or to piers.
Shallow-draft vessels typically have relatively high water resistance due in part to large beam to length ratios, large wetted surfaces, and blunt water contact. Such characteristics provide for the generation of large amounts of resistance, such as turbulence and/or Kelvin wake, and high power requirements. Accordingly, shallow-draft vessels typically have poor seakeeping, poor ride, and poor handling characteristics. Due to these and other operational characteristics, shallow-draft vessels typically are not suited for use in deep water.
Alternatively, deep-draft vessels are often designed with v-hulls having relatively low beam to length ratios to provide the ability to navigate the vessels in deep waters, such as in the oceans and seas. Deep-draft vessels are often designed to provide desired seakeeping (e.g., good seakeeping providing low undesired motion, such as vertical motion or rocking) in high sea states. Deep-draft vessels, however, are typically not available for shallow-water use, such as docking in shallow harbors, river use, and navigation adjacent to shorelines, as the vessels may run-a-ground in these waterways.
A variety of operations require the use of vessels in both shallow and deep waters. As traditionally designed vessels typically have features that provide for optimized use in either shallow water or deep water, but not both, traditionally designed vessels do not provide optimal operating characteristics for both shallow and deep-water use.
The E-Craft is a variable-draft vessel that includes a center hull; a first side hull coupled to a first side of the center hull; a second side hull coupled to a second side of the center hull; and at least one cross support coupling the first and second side hulls, wherein the center hull is configured to be vertically translated with respect to the first and second side hulls. According to a specific embodiment, the vessel further includes lifting mechanism configured to vertically translate the center hull with respect to the first and second side hulls. The lifting mechanism may include a plurality of hydraulic actuators coupled between the center hull and the first and second side hulls.
The center hull may be raised above the water, thereby forcing the side hulls relatively deep into the water (i.e., relatively deep draft). For convenience, such configurations are collectively referred to as the deep-draft-transit mode. The deep-draft-transit mode provides relatively high fuel efficiency as water resistance is relatively low. Also, as the overall hull form has relatively low water plane area, the deep-draft-transit mode provides relatively good seakeeping (i.e., low undesired motion, such as vertical motion or tilting/rocking). The deep-draft-transit mode is of particular use in high seas, as the center hull may be raised relatively high to reduce wave slamming into the underside of the center hull.
In deep-draft-transit mode, the height of the center hull may be adjusted such that a top deck of the center hull approximately matches, for example, the height of a pier or the like. For convenience, a vessel's configuration in which the height of the center hull's top deck is matched to a pier height is referred to as the deep-draft-pier-docking mode. Deep-draft-pier-docking mode provides for simplified loading and offloading of cargo and passengers. For example, in the deep-draft-pier-docking mode, a ramp at one end of the vessel may be unfolded and matched to a pier height so that vehicles may be driven onto and off the vessel. According to a further embodiment, another ramp disposed at the other end of the vessel may be used for off loading vehicles, so that the vehicles may be driven in a forward direction from the vessel.
In deep-draft-transit mode, the center hull may be lifted to a height to provide for simplified cleaning and/or repair of the underside of the center hull without the need to dry dock the vessel. Similarly, with the side hulls lifted above the water (referred to as the recovery mode) the side hulls may be cleaned and/or repaired without the need to dry dock the vessel.
When each of the side hulls and the center hull are in the water, the configuration of the vessel is referred to as the shallow-draft mode. As each of the three hulls is in the water, the hull form is similar to flat-bottomed-monohull vessels and has a relatively high buoyancy and relatively low draft. The additional buoyancy provides that the vessel may be used for relatively heavy cargoes and may be used in a barge like manner. For example, the vessel may be used to transport a number of cars, trucks and other vehicles. Moreover, in the shallow-draft mode, the vessel may be operated in shallow waters, such as in shallow-water harbors, rivers, along shorelines, and landed at beaches (e.g., to load and offload cargo at a beachhead).
The vessel may be operated in a recovery mode in which the center hull may be partially or totally submerged. The recovery mode may be used to recover floating items, such as cargo that has fallen in the water or may be used for rescue work to remove people from the water. For example, passengers from aviation accidents, boating accidents, or soldiers executing military operations may be recovered relatively simply by lowering one or more of the ramps to scoop the passengers from the water. The recovery mode also provides for simplified launching of watercraft that may be stowed on a top deck of the center hull. As briefly described above, the center hull may be vertically translated to such depths that the side hulls are lifted from the water, therefore, providing for maintenance (e.g., cleaning) without the need for dry-docking.
The vessel may be transitioned between various configurations to provide various operational characteristics for a single mission. For example, cargo may be loaded from a pier in deep-draft-pier-docking mode, transported with the center hull raised to a relatively high position in deep-draft-transit mode, and then the center hull may be lowered to shallow-draft mode for delivery of the cargo at a beach or the like.
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