The HELIX 7 CHIRP MEGA SI GPS G4 is one of the Humminbird units released in 2021. As its name suggests, it’s a 7-inch display unit, but as opposed to the older G3 model, it has a richer pixel resolution – 1024H x 600V (up from 800 x 480). The unit does not have touchscreen technology. It also does not have advanced networking features like NMEA 2000, Ethernet, or wireless connectivity. However, it does have the COMs port along with the power connector and the transducer connector to which you can connect an AIS or heading sensor. Plus, it has a microSD card slot for data backup and transfer, as well as software updates and charts.
In terms of sonar, the unit has MEGA Side Imaging, MEGA Down Imaging, and Dual Spectrum CHIRP sonar. It comes with the XNT 9 HW MSI 150 T transducer which supports all these sonar technologies. The transducer has a transom mount and an internal temperature sensor.
For the structure scanning sonar, the transducer casts oval beams. The Side Imaging beams have a coverage of 86° and range up to 800 ft. (244 m) side-to-side at 455 kHz, and 250 ft. (76 m) side-to-side for the MEGA SI. The Down Imaging beams have a coverage of 75° and a depth range of 400 ft. (122 m) for regular DI and 75 ft. (23 m) for MEGA DI. The Dual Spectrum CHIRP beams operate in a CHIRP range of 140-240 kHz. Their beam angles are 25° and 42° and the maximum depth range is 1,200 ft. (365 m).
The unit is a chartplotter as well. It is equipped with the Humminbird Basemap which covers more than 10,000 U.S. lakes with 1-ft. contours. They also offer coastal coverage and provide quite an impressive palette of information. They’re pretty close to Navionics maps.
Speaking of Navionics maps, the unit can support Navionics+, Navionics Platinum+, as well as CoastMaster, LakerMaster, LakeMaster+, and SmartStrike charts. Plus, it has the AutoChart Live feature which gives you the possibility to create your own bathymetric maps.