Sea Technology

NOV 2014

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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www.sea-technology.com November 2014 / st 23 PowerBuoy (LEAP) platform to enable extension and bet- ter resolution of their high-frequency (HF) radar network off the east coast of New Jersey for vessel tracking into New York Harbor. This would turn their radar coverage from mo- nostatic to biostatic, thus improving resolution and detec- tion distance. The platform (LEAP) was to be designed to support a 350-watt payload on a continuous basis with 99 percent availability, including extended periods of low or zero wave conditions, and was deployed 35 miles off the coast. The APB-350 was to provide both power to the HF radar transmitter and to GPS and real-time communications equipment. The program was designed to improve the ma- rine data available to the desktop from detection and track- ing. This would enable the U.S. Navy to utilize its assets in a more effcient manner—a beneft that is desirable for other industries, such as oil and gas. There are approximately 120 HF radars deployed throughout the United States that are contributing to the T he APB-350 PowerBuoy acts as a foating autonomous uninterruptable power supply (UPS) that harvests energy from the waves, stores it on board and distributes power to a payload. It consists of a surface foat that moves in re- sponse to ocean waves and a spar with a reduced response due to a heave plate at its base. A standard mooring keeps the APB-350 on station in the ocean, where it generates electrical power from the heaving motion of waves. Rela- tive motion between the foat and spar drives a push rod into the spar, where linear mechanical motion is converted into electrical power by the power takeoff. This electrical power is then stored in a battery system and is available to power a payload. The internal battery is sized so that pay- load power is constant for up to seven days of fat, calm sea. Any excess power production, which cannot be used by the payload or to charge the battery, is automatically dissipated through a dump resistor. Power allocation and management is automated by the system's internal controller, permitting long-term operation with- out on-site monitoring or user oversight. However, a human-machine interface (HMI) also allows operators to view and control the sys- tem's performance remotely from shore as needed via the APB-350's complement of communication systems. A suite of sensors can be installed on the APB-350 and their data transmitted to shore, in real time. Case Study—LEAP Project During the summer of 2011, the U.S. Navy con- tracted Ocean Power Tech- nologies (Pennington, New Jersey) to provide a Littoral Expeditionary Autonomous Enabling Advanced, Autonomous In-Ocean Security Networks Extending High-Frequency Radar with APB-350 PowerBuoy By Paul Watson Plot of the Almalthea, with non-PowerBuoy HF radar in mono- static mode. Almalthea is the test ship that was used to prove the increased tracking performance of the PowerBuoy HF radar.

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