Shallow Draft High-Speed Ship (SDHSS)
High Speed Shallow Draft Ship (HSSDS)
An Shallow Draft High-Speed Ship (SDHSS) is a strategic ship that can deliver troops, equipment, and sustainment together in sufficient size and at a considerable speed to provide immediate combat power to the Joint Force Commander. Because it has a shallow draft feature, it can bypass established seaports and discharge its combat power wherever there is at least a 10-foot draft and an acceptable offload site. With a C4I suite onboard, commanders can conduct en route planning, receive intelligence updates, and integrate with the Joint Force Commander. By 2005 the SDHSS Shallow Draft High-Speed Shipand HSSDS High Speed Shallow Draft Ship appear to have evolved into the Austere Access High Speed Ship AAHSS .
Through the 1990s the Army engaged in a broad conceptual development process called the "Army after Next" project. The purpose was to develop new ways of thinking about projecting ready-to-fight Army combat units over long ranges. The Army after Next project explored both the air and sea-based technological requirements needed to support operational maneuver from strategic distances. By the turn of the century Army planners had conceived of a new Shallow-Draft High-Speed Ship, or SDHSS, as a key means to enable operational maneuver from strategic distances.
The Army is transforming into a strategically responsive force that will be dominant across the full spectrum of operations. Recent studies have shown it is unlikely that airlift alone will be capable of meeting all the Army's Force Projection/Sustainment objectives associated with the transformation in the near term and that sealift will play a vital role, particularly in follow-on or sustainment phases.
To the maximum extent possible, sealift operations will be conducted via world class Sea Ports of Embarkation (SPOE) to world class Sea Ports of Debarkation (SPOD) using strategic sealift ships. In many areas of the world however, potential SPODs may be physically unable to accommodate these large ships or may be denied by enemy activity. When such is the case, the alternative sealift option has been via Logistics Over the Shore (LOTS) operations. Unfortunately, LOTS operations are complex in nature and are highly affected by sea state - making the LOTS option undesirable to the CINC unless no other alternative exists.
The advent of High Speed Shallow Draft Ships (HSSDS) and their ability to access more ports throughout the world will result in decreased dependence on conventional LOTS capabilities. The Army Transformation wargames, such as the Vigilant Warriors series, have confirmed the future importance of multidimensional operations and the need for US forces to conduct operational maneuver from a strategic distance. One consistent study finding in the Army's wargames has been that the crucial measure of successful force projection is not the speed with which the first combat element engages, but is rather the rate at which the United States and its allies achieve decisive operational superiority. Vigilant Warriors 01 explored the challenges of multidimensional operations and operational maneuver from strategic distances. It featured the Army's Objective Force, and focused on deployment capabilities that can provide assured access, decrease predictability and dwell time, and quickly deliver troops and equipment together in sufficient size to generate immediate combat power.
Of all air and sea, current and future, lift capabilities, Shallow Draft High-Speed Ship (SDHSS) -- because of their speed, throughput capability, and capacity -- most significantly impacted force closure. Air deployment remains the only way to rapidly establish the initial crisis-response presence of air expeditionary forces and a division equivalent of ground forces needed to preclude enemy forces' early success. But after a few days, SDHSS had a distinct advantage. It was the only strategic platform that could deliver troops and equipment together in sufficient size to bring immediate combat power to bear. While in transit, commanders could conduct en route planning and receive intelligence updates. Moreover, the SDHSS did not require a fixed port because it could discharge its combat power wherever there was at least a 10-foot draft and an acceptable beach gradient or discharge site. Troops drove the future combat system (FCS) from the ship ready to fight onward to the tactical assembly area.
The intratheater version of the strategic SDHSS is the theater support vessel (TSV) - the Army's future watercraft. Shallow-draft high-speed sealift (SDHSS) vessels; theater support vessels (TSVs); APS vessels that do not require docking to offload; and a new family of all-weather, day-and-night SSTOL and VTOL aircraft create new sustainment options. The enemy is not able to determine with certainty where and how U.S. sustainment will enter and exit the JOA and combat zone.
Faster inter-theater sealift provides a larger payload than heavylift aircraft with a significant speed advantage over conventional ships. Using advanced hull designs, high power, fuel efficient machinery, and advanced structural designs using light weight, high strength-materials, it will be technologically feasible in 10 years to build a HSS ship capable of a speed of at least 40 knots, with a range of 10,000 nautical miles carrying a payload of 5,000 short tons and able to onload and offload cargo in undeveloped ports and at sea. Generally these ships would deliver units or supplies to a sea base or ISB, but, if the JOA is contiguous to the sea, units and resupply could be delivered directly to the coast or to the objective. These ships could also be configured to support direct delivery of sustainment and small units by use of small manned or unmanned aircraft. Fast sealift ships would be particularly useful if the initial RDO force was being replaced or augmented by a more robust force.
Principles of hydrodynamics suggest that a 40-knot sealift ship transporting material and troops rapidly from CONUS to an area of military engagement would be a large ship (length greater than 1,400 feet) to meet requirements for power and displacement hull design. Although such a large, high-speed ship is an alternative for replenishment of the seabase configuration and would minimize the demands on strategic airlift, other operational considerations do not make the concept attractive. Areas of concern include the deep draft of the ship that limits possible geographical areas of operation, the present limited useful payload of available platforms, the potential for heavy casualties when under attack, and the inability to transit the Panama Canal.
Development of marine vessels capable of transporting large cargo tonnage at speeds in excess of 50 kts continues to be a challenge to the naval architect. While 50-kt craft do exist they are of modest size, require very large horsepower per ton of displacement, and cannot transport large payloads over intercontinental routes. The most current project in this arena is the Fast-Ship Atlantic program. This is an 860-ft, 40-kt ship with a cargo capacity of 10,000 LT. It is a semi-displacement type hull operating at a speed-length ratio of about 1.4.
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