The EdgeTech 3100-P Portable Sub-Bottom Profiling System is a low cost portable sub-bottom profiler system. It uses Full Spectrum (“chirp”) pulses to create high definition image slices of sub-bottom structure below the bottom. It can be used in rivers, lakes, ponds, and in the ocean. The EdgeTech SB-424 towfish has a frequency range from 4 - 24 kHz. This towfish uses special designed transmitters with low Q- wide band characteristics best suited for “chirp” transmissions. Two multi element line array hydro-phones are installed in the tow vehicle to reduce acoustic scattering from the sides. This results in a narrower across/along track beam pattern.