Development of a new Unmanned Semi-Submersible (USS) vehicle

C & C Technologies in Lafayette, LA in cooperation with the Naval Research Laboratory (NRL) Mapping, Charting and Geodesy Branch at Stennis Space Center, MS and Autonomous Surface Vehicles, Ltd. in W. Sussex, UK, is implementing a multiyear development program of an Unmanned Semi-Submersible (USS) vehicle. Originally sponsored by the National Oceanic and Atmospheric Administration (NOAA), the goal of this project is to develop an unmanned, compact, rugged, and high-endurance vehicle capable of acquiring sensor based measurements and yielding higher coverage rates per day in sea states beyond those possible with a small manned conventional survey boat. Furthermore, the USS will facilitate an evaluation of the full potential of a rugged semi-submersible as a low cost force multiplier for littoral mapping purposes in both commercial and military applications. Vehicle attributes include a notable sea-keeping capability that offers promise for nautical charting surveys, military applications, and homeland defense programs. This program builds upon earlier NRL research with the unmanned semi-submersible survey prototype, ORCA (Oceanographic Remotely Controlled Automaton) to support the Naval Oceanographic Office (NAVOCEANO). The ORCA was an air-breathing vessel with a majority of its structure traveling just below the water surface. The ORCA's radio antennae were affixed to a snorkel, which allowed for remote vehicle command and control in addition to real-time data transfer. The ORCA also used Differential Global Positioning System (DGPS) for precise positioning. In a similar fashion, the newly developed USS navigates submerged with only a narrow sail structure extending above the waterline. The USS design criteria are based upon the maximum integration of readily available Commercial Off The Shelf (COTS) hardware and instrumentation acquired largely from small boat technology. Requirements mandate a form factor suitable for stern ramp launch and retrieval, the capacity to operate dockside without special equipment, a re-configurable payload capability, a survey speed of at least six knots, and an endurance of at least two days. Overall vehicle height is restrained to allow for safe maintenance work on the deck of a moving ship and to accommodate shipping and storage within standard ISO containers. The USS program is aimedto provide risk reduction to support the Navy Unmanned Underwater Vehicle (UUV) Master Plan by evaluating new sensors, modularity, commonality of equipment, and experimentation with UUV systems. This paper discusses the USS concept, the decision making process, program milestones, and the vehicle design process including establishment of the performance criteria, hydrodynamic model testing, computer simulation, manufacture, and sea testing results.