Non-Lethal Swimmer Deterrent
Navy SBIR FY2008.2

Sol No.: Navy SBIR FY2008.2
Topic No.: N08-176
Topic Title: Non-Lethal Swimmer Deterrent
Proposal No.: N082-176-0853
Firm: Diversified Technologies, Inc.
35 Wiggins Ave.
Bedford, Massachusetts 01730
Contact: Nicholas Reinhardt
Phone: (781) 275-9444
Web Site:
Abstract: A non-lethal but effective electrical swimmer barrier is proposed that will take advantage of ocean oil-barrier deployment technology, the conductive properties of near-coast waters, and the physiological sensitivities of human swimmers to electrical shocks. Experimental validation will be made of the use of intermittent, spatially-distributed burst-mode current pulses of short duration to create enhanced deterrence without incurring added risk of lethality. A novel secondary-electrode pulse current distribution system will localize the swimmer interdiction areas and provide the desired effect-free regions close to ships and piers. Feedback control of the deployable power supplies will be used to compensate for temperature changes, variations in salinity, water pollution, ship proximity, and configuration of the area to be protected. To energize the system, either shore or ship's power can be used; power demand is estimated to be 50 Watts per meter of coverage. The entire electrode set and its power supply will be readily deployable and retrievable by two persons working from a 24- to 28-foot boat. Electrode corrosion will be prevented by electrochemical techniques already proven in DTI's pulsed-electric-field (PEF) sewage-treatment and food-processing equipment.
Benefits: Commercial applications include equipment for shark exclusion from beaches, wildlife nuisance and swimmer exclusion from intakes and other aquatic installations, and fish-herding, as well as general pulsed electric field technology for electrodes in conductive media for systems such as PEF food and wastewater treatment.