Abstract: A power system for an unmanned surface vehicle includes a fuel cell including a fuel cell stack, where the fuel cell stack includes a fuel inlet. The power system also includes a fuel storage including at least one fuel-storage module fluidly connected to the fuel inlet of the fuel cell stack. The fuel-storage module is a source of energy for the fuel cell. The power system also includes a fuel and thermal management system fluidly connected to the fuel inlet of the fuel cell stack. The fuel and thermal management system includes a heat exchanger in thermal communication with the fuel cell stack for removing waste heat produced by the fuel cell stack during operation. The fuel and thermal management system also includes a flow valve, a pressure regulator, and a conduit.

Abstract: A method including operating vehicles through a medium. The vehicles are subject to advection due to movement of the medium. The vehicles are in sufficient proximity to each other that one or more conditions of the medium are about equivalent for the vehicles. The method also includes applying an incremental sequence of about equivalent thrust forces to the plurality of vehicles to generate about equivalent incremental changes in a plurality of steady-state average drag forces for the plurality of vehicles. The method also includes measuring a plurality of speed changes for the plurality of vehicles. The method also includes calculating, from the plurality of speed changes, a plurality of relative speed performance statistics for relative speed performance between pairs of vehicles, wherein calculating is performed independently of the one or more conditions of the medium.

Abstract: A method including operating a vehicle in a medium. The vehicle is subject to advection due to movement of the medium. The method also includes measuring, using a navigation system, positions of a vehicle over time. The method also includes measuring, using a directional sensor, a course-through-medium over the time. The method also includes calculating, using the positions and the course-through-medium, a variation of a speed-over-ground of the vehicle over the time as a function of the course-through-medium over the time. The method also includes concurrently estimating, using the variation, 1) an average speed-through-medium for the vehicle over the time, and 2) an advection rate of the medium, and 3) an advection direction of the medium.

Abstract: A method including propelling a vehicle disposed in a medium. The vehicle includes a body, a propulsion mechanism connected to the body, and a direction control system. The vehicle is subject to advection caused by movement of the medium. The method also includes commanding the vehicle to perform a navigation course comprising a closed course-over-ground. The method also includes periodically adjusting navigation of the vehicle along the closed course-over-ground such that a course-through-the-medium turn-rate is varied in a manner that causes a course-over-ground turn-rate of the vehicle to be held constant, thereby minimizing the impact of medium advection on vehicle speed over ground.

Abstract: A method including propelling a vehicle disposed in a medium. The vehicle includes a body, a propulsion mechanism connected to the body, and a direction control system. The vehicle is subject to advection caused by movement of the medium. The method also includes commanding the vehicle to perform a navigation course comprising a closed course-over-ground. The method also includes periodically adjusting navigation of the vehicle along the closed course-over-ground such that a course-through-the-medium turn-rate is varied in a manner that causes a course-over-ground turn-rate of the vehicle to be held constant, thereby minimizing the impact of medium advection on vehicle speed over ground.

Abstract: A method including operating a vehicle in a medium. The vehicle is subject to advection due to movement of the medium. The method also includes measuring, using a navigation system, positions of a vehicle over time. The method also includes measuring, using a directional sensor, a course-through-medium over the time. The method also includes calculating, using the positions and the course-through-medium, a variation of a speed-over-ground of the vehicle over the time as a function of the course-through-medium over the time. The method also includes concurrently estimating, using the variation, 1) an average speed-through-medium for the vehicle over the time, and 2) an advection rate of the medium, and 3) an advection direction of the medium.

Abstract: A method including operating vehicles through a medium. The vehicles are subject to advection due to movement of the medium. The vehicles are in sufficient proximity to each other that one or more conditions of the medium are about equivalent for the vehicles. The method also includes applying an incremental sequence of about equivalent thrust forces to the plurality of vehicles to generate about equivalent incremental changes in a plurality of steady-state average drag forces for the plurality of vehicles. The method also includes measuring a plurality of speed changes for the plurality of vehicles. The method also includes calculating, from the plurality of speed changes, a plurality of relative speed performance statistics for relative speed performance between pairs of vehicles, wherein calculating is performed independently of the one or more conditions of the medium.

Abstract: An autonomous watercraft with a waterproof container that houses a satellite communication terminal. The waterproof container includes a first shell mounted on a deck of the watercraft and that has a sealed first interior space that contains satellite communication circuitry of the terminal. The waterproof container also includes a second shell mounted under the deck of the watercraft and that has a sealed second interior space that contains the processing circuitry of the terminal. The first and second shells include ports configured to receive connectors for communication signaling and/or power. The first shell can also include a pressure port to pressurize the first interior space for use in leak detection. The shells can also include heat sinks to cool the satellite communication terminal.

Abstract: An autonomous watercraft with a waterproof container that houses a satellite communication terminal. The waterproof container includes a first shell mounted on a deck of the watercraft and that has a sealed first interior space that contains satellite communication circuitry of the terminal. The waterproof container also includes a second shell mounted under the deck of the watercraft and that has a sealed second interior space that contains the processing circuitry of the terminal. The first and second shells include ports configured to receive connectors for communication signaling and/or power. The first shell can also include a pressure port to pressurize the first interior space for use in leak detection. The shells can also include heat sinks to cool the satellite communication terminal.

Abstract: An autonomous watercraft with a waterproof container that houses a satellite communication terminal. The waterproof container includes a first shell mounted on a deck of the watercraft and that has a sealed first interior space that contains satellite communication circuitry of the terminal. The waterproof container also includes a second shell mounted under the deck of the watercraft and that has a sealed second interior space that contains the processing circuitry of the terminal. The first and second shells include ports configured to receive connectors for communication signaling and/or power. The first shell can also include a pressure port to pressurize the first interior space for use in leak detection. The shells can also include heat sinks to cool the satellite communication terminal.

Abstract: A power system for an unmanned surface vehicle is disclosed. In one embodiment, the power system includes a fuel cell, a fuel storage, and an air management system. The fuel cell includes a fuel cell stack. The fuel cell stack includes a fuel inlet, an air inlet, and an exhaust outlet. The fuel storage includes at least one fuel-storage module fluidly connected to the fuel inlet of the fuel cell stack. The fuel-storage module is a source of energy for the fuel cell. The air management system is fluidly connected to the air inlet and the exhaust outlet of the fuel cell. An air snorkel is part of the air management system and provides air to operate the fuel cell while the unmanned surface vehicle is deployed on a surface of a body of water. The air snorkel includes an intake and an exhaust.