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James Joslin Mechanical Engineer jbjoslin@uw.edu Phone 206-543-7844 |
Biosketch
James Joslin joined the ocean engineering team at APL-UW in the summer of 2015 after four years in the UW Mechanical Engineering Department. His research interests include marine renewable energy, instrumentation for environmental monitoring, underwater vehicles, robotics, and hydrodynamics. James supports a wide variety of marine projects from system design and fabrication to the management of field deployments and testing.
In addition to his research, James is actively pursuing the commercialization of technologies developed at APL-UW through a University of Washington spinoff.
Education
B.S. Mechanical Engineering, Dartmouth College, 2005
M.S. Mechanical Engineering, Dartmouth College, 2007
Ph.D. Mechanical Engineering, University of Washington, 2015
Videos
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Persistent Environmental Monitoring Near an Operational Wave Energy Converter In the first demonstration of the technology, the WEC supplied all the power needed by the multi-sensor Adapatable Monitoring Package. |
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15 Jul 2019
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For over 6 months, ocean environment observations were captured by the sensor package powered only by the ocean waves at the U.S. Navy Wave Energy Test Site off Oahu, HI. |
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Wave Energy Buoy that Self-deployes (WEBS) The Wave Energy Buoy that Self-deploys (WEBS) converts surface wave energy to mechanical and electrical power. WEBS is an easily deployed power station that can operate anywhere in the off-shore environment. Potential applications include power sensor payloads for scientific instrumentation; power station for autonomous systems, undersea vehicles, and/or surface vessels; and communications relay. |
13 Dec 2016
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Publications |
2000-present and while at APL-UW |
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Lessons learned from the design and operation of a small-scale cross-flow tidal turbine Bassett, C., P. Gibbs, H. Wood, R.J. Cavagnaro, B. Cunningham, J. Dosher, J. Joslin, and B. Polagye, "Lessons learned from the design and operation of a small-scale cross-flow tidal turbine," J. Ocean Eng. Mar. Energy, EOR, doi:10.1007/s40722-025-00411-y, 2025. |
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1 Jul 2025 ![]() |
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In 2023, a first-generation prototype of a small-scale marine current turbine was operated in Sequim Bay, Washington (USA) for 141 days. The system, referred to as the Turbine Lander, was the product of a laboratory-to-field effort to develop a system that enables enhanced ocean sensing or vehicle recharge in remote, energetic settings. The turbine consists of a vertical-axis, cantilevered rotor (1.19 m x 0.85 m) with four foils installed on a gravity foundation. A broader range of constraints including the deployment strategy, site characteristics, and estimated loads, drove the system's design. This work presents the design, characterization, operation, and post-recovery engineering assessment of the Turbine Lander. Pre-deployment characterization efforts yielded a peak power coefficient of approximately 0.3 for the rotor, although system losses resulted in much lower water-to-wire efficiencies under most operating conditions. The results demonstrate the importance of co-design among key components of the powertrain and control systems to achieve acceptable system efficiency across operating conditions. |
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Adaptable and distributed sensing in coastal waters: Design and performance of the μFloat system Harrison, T.W., C. Crisp, J. Noe, J.B. Joslin, C. Riel, M. Dunbabin, J. Neasham, T.R. Mundon, and B. Polagye, "Adaptable and distributed sensing in coastal waters: Design and performance of the μFloat system," Field Rob., 3, 516-543, doi:10.55417/fr.2023016, 2023. |
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1 Mar 2023 ![]() |
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Buoyancy-controlled underwater floats have produced a wealth of in situ observational data from the open ocean. When deployed in large numbers, or "distributed arrays," floats offer a unique capacity to concurrently map 3D fields of critical environmental variables, such as currents, temperatures, and dissolved oxygen. This sensing paradigm is equally relevant in coastal waters, yet it remains underutilized due to economic and technical limitations of existing platforms. To address this gap, we developed an array of 25 μFloats that can actuate vertically in the water column by controlling their buoyancy, but are otherwise Lagrangian. Underwater positioning is achieved by acoustic localization using low-bandwidth communication with GPS-equipped surface buoys. The µFloat features a high-volume buoyancy engine that provides a 9% density change, enabling automatic ballasting and vertical control from fresh to salt water (~3% density change) with reserve capacity for external sensors. |
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Effect of heave plate hydrodynamic force parameterization on a two-body wave energy converter Rusch, C.J., J. Joslin, B.D. Maurer, and B.L. Polagye, "Effect of heave plate hydrodynamic force parameterization on a two-body wave energy converter," J. Ocean Eng. Mar. Energy, 8, 355-367, doi:10.1007/s40722-022-00236-z, 2022. |
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12 Jun 2022 ![]() |
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Heave plates are one approach to generating the reaction force necessary to harvest energy from ocean waves. In a Morison equation description of the hydrodynamic force, the components of drag and added mass depend primarily on the heave plate oscillation. These terms may be parameterized in three ways: (1) as a single coefficient invariant across sea state, most accurate at the reference sea state, (2) coefficients dependent on the oscillation amplitude, but invariant in phase, that are most accurate for relatively small amplitude motions, and (3) coefficients dependent on both oscillation amplitude and phase, which are accurate for all oscillation amplitudes. We validate a MATLAB model for a two-body point absorber wave energy converter against field data and a dynamical model constructed in ProteusDS. We then use the MATLAB model to evaluate the effect of these parameterizations on estimates of heave plate motion, tension between the float and heave plate, and wave energy converter electrical power output. We find that power predictions using amplitude-dependent coefficients differ by up to 30% from models using invariant coefficients for regular waves ranging in height from 0.5 to 1.9 m. Amplitude- and phase-dependent coefficients, however, yield less than a 5% change when compared with coefficients dependent on amplitude only. This suggests that amplitude-dependent coefficients can be important for accurate wave energy converter modeling, but the added complexity of phase-dependent coefficients yields little further benefit. We show similar, though less pronounced, trends in maximum tether tension, but note that heave plate motion has only a weak dependence on coefficient fidelity. Finally, we emphasize the importance of using experimentally derived added mass over that calculated from boundary element methods, which can lead to substantial under-prediction of power output and peak tether tension. |
In The News
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Plainsight and MarineSitu Using 'Computer Vision' to Protect Sea Creatures Forbes, Jeff Kart Plainsight, an artificial intelligence company in the United States, has partnered with MarineSitu, a hardware and software provider and spinoff from the University of Washington. The focus is on enabling marine energy devices to coexist harmoniously with aquatic life. |
28 Jan 2023
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Eyes Underwater Watching Aquatic Wildlife Environmental Monitor, Karla Lant Recent work from researchers at the University of Washington offers a promising new way to harvest energy from waves at sea and use that energy to power an Adaptable Monitoring Package. |
9 Jul 2019
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Converting ocean waves into electricity poses challenges—and promise Columns Magazine, Jon Marmor In the glorious Pacific Ocean waters off the windward coast of O’ahu, waves crash along the Kailua coast. But it isn’t just surfers who salivate over those ocean jewels. Scientists believe the motion of the ocean could bring the promise of something even more important: clean energy. |
3 Jun 2019
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