ADVANCED HULLFORMS
Transformable craft concept is challenging brief T
HE Office of Naval Research (ONR) in the US recently awarded four Phase 1
study contracts for the Seabase Connector Transformable-Craft (T-Craft) project, a ‘transformable’ high-speed vessel that deploys in an unloaded condition and travels up to 2500nm to reach the sea base. Once it had made a ‘connection’, the T-Craft would then have the ability to serve as a high- speed connector, carrying a payload of up to 750 long tons, while travelling at a speed of 40knots or more, and transporting troops as well as wheeled and tracked vehicles to beachheads. The four contracts for Phase 1 of the T-Craft project are understood to have been awarded to Alion Science & Technology, Textron, Aker Mandal, and Navatek. The T-Craft will have three modes of
operation: fuel-efficient or sea keeping mode; high-speed or shallow water mode; and an amphibious mode to travel over sand bars and mud flats. In keeping with US Navy and Marine Corps’ seabasing strategy, a large ‘parent’ ship stationed 100miles - 200miles offshore would be ‘serviced’ by a T-Craft, which would be designed to travel between parent ships and beachheads to deliver troops, supplies, and vehicles. Seabasing will be used by the military services
to build floating bases in areas in which ground bases cannot be established. In Phase 1 of the project, the four companies
are developing preliminary design concepts to be included in the T-Craft amphibious connector prototype. In Phase II, the contractors down- selected by the ONR Phase II will develop detailed designs that can be model tested against one another to validate performance, and in Phase II, a single contractor will build and test the T-Craft prototype demonstrator. ‘The purpose of the T-Craft is to develop
and demonstrate the technologies to facilitate rapid transfer of materials to shore, in support
Artist’s concept of Navatek’s proposal for the ONR T-Craft programme.
of naval seabasing,’ Vice Admiral Scott Fry, (US Navy Retired), Alion Sector senior vice president and manager of the engineering and integration solutions sector explained. ‘The US Navy’s vision for seabasing requires the ability to rapidly transfer cargo, stores, and vehicles from a seabase to a beach.’ The Navatek T-Craft concept is understood to include an innovative Captive-Air Amphibious Transporter called C-AAT which will be carried aboard the ship. The T-Craft will also incorporate an innovative Navatek-designed propulsion system. Navatek said it holds a total of seven US and international patents with relevance to the T-Craft project on its advanced ship designs, with 12 more patents pending (see box).
In a recent presentation, staff at the ONR provided further information about the T-Craft and about the technical challenges that will need to be overcome if the project is to succeed. It describes the T-Craft as a fuel efficient
vessel capable of self deployment, and high- speed transit. Fully amphibious, the T-Craft would be beachable, with a speed of 40kt in Sea State 4. It would need to have excellent seakeeping when at the seabase, and a payload capacity of 4-10 M1A1 tanks or its equivalent. ‘The T-Craft will deploy in an unloaded
condition (at a range of 2500nm) from the intermediate support base to the sea base, and then be used as a sea base connector, transporting wheeled and tracked vehicles through the surf zone and onto the beach. The craft operates in a fuel-efficient mode for long distance open ocean transits, then transforms to a good seakeeping mode for rapid sea- based military vehicle transfer operations. Once loaded, the craft travels at high-speed in shallow water mode over sand bars and mud flats to the beach, where it transforms to a fully amphibious mode for final delivery of the payload to firm ground,’ noted the ONR. To meet this exacting brief, the T-Craft will
need to exceed current capability in a number of respects, including an increased payload capacity of 400% to 1000%, speeds greater than 40kts, and a ‘feet dry’ on the beach capability. ‘Current US Navy surface ‘connectors’ have
to be carried into theatre within the well decks of our amphibious ships. These amphibious connectors carry small payloads over small distances and can only operate in low sea states,’ noted the ONR. The challenges to be overcome in developing such craft therefore include:
Below-water view of Navatek’s T-Craft hullform. WARSHIP TECHNOLOGY MAY 2007 11
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