Humminbird Depth sounder Helix 7 Chirp GPS SI G4 The Helix 7 CHIRP GPS SI G4 features side imaging (no MEGEA-SI), down imaging and dual spectrum CHIRP. It is equipped with a large 7 inch / 178mm color display. With 4000 watts of transmit power, this depth sounder can reach depths of up to 360 meters (DS), 120 meds (DI) and 30 meters (SI). Dual Spectrum Chirp makes it a true all-round echo sounder, both for shallow water and for greater depths. Includes a preloaded Humminbird Basemap nautical chart. Other features: AutoChart Live, Navionics Plus charts capable.