Seapower - September 2007

Tri-Modal Connection
Four companies vie to build the T-Craft sea-to-shore transport demonstrator

By RICHARD R. BURGESS, Managing Editor

Game Changer

The Navy is funding the demonstration of game-changing technology to transfer heavy military vehicles from a sea base to shore in a project that faces considerable technical challenges.

The Office of Naval Research (ONR), which in 2006 began an effort called Innovative Naval Prototypes for Seabasing, is sponsoring a competition to develop a prototype demonstrator for the Sea Base Connector Transformable-Craft (T-Craft). The high-speed T-Craft will be designed to transport heavy wheeled and tracked vehicles from a sea base to an unprepared shore in an assault or logistics mission. If developed to an operational type, the T-Craft would enable U.S. forces to reduce reliance on friendly ports for access to expeditionary theaters of operation.

The ONR expects to award approximately $10 million in Phase 2 of the T-Craft competition in October to a design team to build and test a model of the winning design. If the project proceeds to a third phase in October 2009, the team could be awarded approximately $150 million to build a prototype.

The requirements for the demonstrator are daunting for a single craft. The T-Craft must be able to travel in an unloaded condition 2,500 nautical miles from a support base to a sea base, where it will be used as a connector to the shore. The T-Craft is envisioned to

operate in three modes, according to ONR’s broad agency announcement, and shift from one mode to the next without any external assistance.

The craft should be able to operate in a fuel-efficient mode ( approximately 20 knots) without cargo for open-ocean transits through Sea State 5, be capable of operations through Sea State 6 and survivable through Sea State 8. Sea State 5 sees, among other things, wind speeds of 21 to 25 knots and waves of eight to

12 feet high, while Sea State 8 involves winds of 49 to 57 knots and waves of 45 to 60 feet.

In the high-speed, shallow-water mode for transit with a full cargo load, the T-craft is envisioned to operate at speeds of approximately 40 knots in Sea State 4 to distances of 500 to 600 nautical miles without refueling.

The T-Craft will be designed to be able to transition to an amphibious mode to transit sand bars and mud flats and discharge its cargo on dry land.

Another desired characteristic is the capability to “mitigate wave-induced motions in Sea State 4/5 to enable rapid vehicle transfer between the T-Craft and a Maritime Prepositioning Force (Future)/Sealift ship,” according to the ONR announcement.

The T-Craft is not required to be stealthy, operate from the well decks of amphibious ships or handle pallets and containers.

Although ONR requires the demonstrator vessel to be operated by a crew of two or three, it recognizes that an operational vessel designed for transits of thousands of miles would require a larger crew. The demonstrator crew is small simply for the purposes of economy of the demonstration, but the Navy expects that automation will allow handling of an operational version with a watch crew of only two or three at a time, said Kelly Cooper, ONR’s T-Craft project manager.