Each year, tens of thousands of crab pots are lost in the Chesapeake Bay, costing watermen valuable gear and wasting resources as they continue to trap marine life even after they are lost. To tackle this problem, a team of undergraduates in the Department of Electrical and Computer Engineering developed Crab-Back, a low-cost acoustic release system that allows watermen to retrieve lost traps even after their main buoy lines are cut.
Miles Durham, Vincent Lu, Christian Torres, and Benjamin Shan presented their prototype on April 28 at the Whiting School of Engineering’s Design Day, an annual event that showcases students’ solutions to real-world problems.
Watermen lose an estimated 12% to 20% of their crab pots each year, leaving roughly 72,000 to 120,000 traps on the Chesapeake Bay floor. These derelict pots contribute to ghost fishing, trapping and killing an estimated 3.3 million crabs annually.
“Attending school in Maryland, we’ve grown fond of the Chesapeake Bay,” says Durham. “We wanted to make something that benefits both watermen and the health of the Bay itself.”
Designed for real-world crabbing conditions, Crab-Back attaches directly to a crab pot and remains dormant unless a primary buoy line is lost or cut.
“When a crabber realizes a buoy line is cut, they place a handheld remote in the water and press a button,” says Lu. “The module on the crab pot receives the signal and releases a small backup buoy, making the pot easy to locate.”
Because radio waves do not travel effectively underwater, the students had to overcome a big technical hurdle: creating a custom communication system capable of detecting and processing acoustic signals reliably. The students designed their own hydrophone using piezoelectric discs and built a custom circuit that filters unwanted frequencies, amplifies weak signals, and converts underwater sound into digital pulses that trigger the device.
To reduce costs, the team selected inexpensive but functional components, including microcontrollers and servo motors, while also designing a low-power wake-up mode that allows the system to remain dormant for extended periods and achieve an estimated battery life of six to nine months.
“We first began with indoor tests using water-filled containers before moving to pools on and around campus—including the fountain at the President’s Garden—where Crab-Back successfully transmitted and received signals at distances of up to 10 feet underwater,” says Torres. While time constraints limited longer-distance trials, their calculations suggest the system could potentially operate at ranges of 20 to 30 feet.
Real-world feedback also influenced the project. “We were able to consult Chesapeake Bay waterman CJ Canby, known as “Crab Dad” on YouTube, whose experience managing roughly 1,500 pots helped better shape our understanding of what commercial crabbers would need from a new technology,” says Shan.
Following early success at HopStart, Johns Hopkins’ startup competition, where the team earned a Pava Center for Entrepreneurship Award and placed second in the General Ventures I category, the students are now exploring how to further refine Crab-Back into a stronger solution for working watermen.
“We hope to provide peace of mind for crabbers,” says Durham, “while creating a practical tool that can help protect both their livelihoods and the Bay.”