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Mega DI+,
Mega SI+
1,200' 2D
400' DI,
125' SI
AC Live

The HELIX 8 CHIRP MEGA SI+ GPS G3N is also one of the new Humminbird fish finder and chartplotter combos released in 2019. It’s also one of the first 8-inch display units of the HELIX series. As its name suggests, it integrates MEGA Imaging+ sonar which offers extended range and depth, plus 20% more detail than MEGA Imaging. It also includes the MEGA Imaging+ transducer. For reference, this is the Humminbird part number 410830-1.

Technical Details and Specifications

  • Display: 8″ diagonal, 1024H x 600V pixel resolution, WVGA 16-bit color TFT, with LED backlight
  • Sonar: Dual Spectrum CHIRP, CHIRP MEGA Side Imaging+, MEGA Down Imaging+
  • Transducer: Transom XM 9 HW MSI T
  • Frequency and Coverage:
      • Dual Spectrum CHIRP:

    2D Full mode: 150-220 kHz (adjustable) / 42°
    2D Wide mode: 140-200 kHz / 42°
    2D Narrow Mode: 180-240 kHz / 25°

      • Down Imaging:

    435-535 kHz / 75°
    800-860 kHz / 45°
    1100-1200 kHz / 75°

      • Side Imaging:

    405-535 kHz / 2x 86° / 800 ft (244 m) side-to-side
    780-840 kHz / 2x 86° / 250 ft (76 m) side-to-side
    1050-1175 kHz / 2x 86° / 400 ft (122 m) side-to-side

  • Max. Depth Capability (with the included transducer):
    • Dual Spectrum CHIRP: 1,200 ft (365 m)
    • Down Imaging: 400 ft (122 m)
    • Side Imaging: 125 ft (38 m)
  • Power Output: 1,000 Watts (RMS)
  • Power Input: 10.8-20V DC
  • Power Draw: 1 Amp
  • GPS: Internal
  • Cartography: Humminbird Basemap
  • Routes, Waypoints, Tracks: 45; 2,750; 50 (20,000 points each)

Sonar and transducer

The Humminbird HELIX 8 CHIRP MEGA SI+ GPS G3N offers three types of sonar. These are Dual Spectrum CHIRP (2D), Down Imaging, and Side Imaging. Of course, as its name suggests, it has MEGA Imaging+ modes for its DI and SI sonar. The unit itself supports multiple base frequencies, including 50/83/200/455/800 kHz & 1.2 MHz. Also, since it’s a G3N unit, it supports Ethernet and therefore, it is 360 Imaging capable.

The unit includes the MEGA Imaging+ transducer XM 9 HW MSI T. This transducer is superior to the XNT 9 HW MSI 150 T included with the HELIX 7 CHIRP MEGA SI GPS G3N. It’s slightly larger, it features a metallic (transom) mount, has 20′ (6 m) of cable, and integrates a temperature sensor. And of course, it provides a better SI and DI range.

The unit’s Dual Spectrum CHIRP sonar offers three modes, these being Full, Wide, and Narrow. For all these modes, the transducer uses conical beams. Their coverage is 42° @ Full Mode (150-220 kHz), 42° @ Wide Mode (140-200 kHz), and 25° @ Narrow Mode (180-240 kHz). The Wide and Narrow modes have fixed CHIRP intervals; however, the Full Mode is adjustable. Its default interval is 150-220 kHz, but it can be adjusted for the full 2D CHIRP range, between 140-240 kHz. Also, the maximum depth that can be reached by the 2D CHIRP beams is 1,200 ft (365 m) (when using Wide Mode).

For Side Imaging, the transducer uses thin beams with a coverage of 86°, and a maximum side-to-side range of 800 (244 m) at 405-505 kHz. The MEGA SI+ (1050-1175 kHz) range is 400 ft (122 m) side-to-side, 200 ft (61 m) on each side, which is quite a bit more than the regular MEGA SI which offers only 250 ft (76 m) full coverage. The depth capability of the Side Imaging and MEGA SI+ is not specified. However, since it’s not as great as Down Imaging, our estimation is 125 ft (38 m).

For Down Imaging, the transducer also uses thin beams, not conical. Their coverage is 75° @ 435-535 kHz & 1100-1200 kHz, while for the 800-860 kHz CHIRP interval, the coverage is 45°. Evidently, the MEGA DI+ beam (1100-1200 kHz) offers the best imaging. Its depth capability is 200 ft (61 m), while the greatest depth that can be achieved by the systems Down Imaging sonar is 400 ft (122 m) when using the 435-535 kHz mode.

The unit offers the full range of standard sonar features. To begin with, it has the SwitchFire and Selective Fish ID applications. SwitchFire is a quick noise filter which allows you to select between Clear Mode and Max. Mode. Clear Mode removes most of the clutter on the display keeping only the biggest targets. Max. Mode brings all the 2D sonar information on the display so you can view all the potential fish targets.

Selective Fish ID assigns fish icons to the suspended targets interpreted by the unit as fish. You can also choose to see the depth of each fish next to it.

Apart from these, the unit also offers Sonar Recording, Real Time Sonar, Bottom Lock, Flasher view, Depth Alarm, Fish Alarm, and more.

Navigation features

Like most other Humminbird HELIX units from the G3 series, the HELIX 8 CHIRP MEGA SI+ GPS G3N includes the Humminbird Basemap platform. These are charts based on official charts; they offer detail pretty close to the Navionics+ charts. They cover both inland and coastal waters. For inland fishing, they provide coverage for more than 10,000 U.S. lakes, while for off-shore fishing they cover the whole U.S. East and West Coast, showing markers, buoys, marinas, hazards, navigation aids, spot soundings and many other points of interest.

Of course, the unit is compatible with multiple premium charts. For example, you can upgrade its chart base to Navionics+, Navionics Platinum+, LakeMaster, or LakeMaster Plus. It is also compatible with the SmartStrike fishing charts.

The unit also has the AutoChart Live feature. This application is similar to the SonarChart feature offered by the Navionics charts. It uses the 2D sonar information and the GPS information in order to reveal and draw the depth contours of a body of water on the map. This being said, it gives you the possibility to create and use personalized charts with the most up-to-date depth contours.

The HELIX 8 CHIRP MEGA SI+ GPS G3N is equipped with a fast and accurate internal GPS system. It can also support external GPS heading sensors and Radar. It can use WAAS, EGNOS, and MSAS for enhanced fixes, an also makes available a GPS speed feature.

The unit can save up to 2,750 waypoints in its memory. It gives you the possibility to personalize each waypoint, choosing from an extensive database of icons. It also has route creation and track recording functions, allowing you to save up to 45 routes, and 50 tracks with up to 20,000 points per track.

Last but not least, the unit is i-Pilot Link compatible. It also supports AIS data.

Control unit features

The HELIX 8 CHIRP MEGA SI+ GPS G3N features an 8″ display, with a pixel matrix of 1024 x 600. It has LED backlight and provides excellent readability even in direct sunlight, or from sharp angles up to 85°. It’s also IPX7 waterproof.

The unit’s interface is keypad operated. It does not have cross-touch technology.

Like all the other G3N units, the HELIX 410830-1 offers superior networking capabilities. It is Ethernet and NMEA 2000 compatible, and therefore, it can provide data from various other navigation instruments such as CHIRP Radar, AIS units, etc. Plus, it has wireless connectivity. It is compatible with the Bluetooth remote control RC2, so you can control it from distance. You can also sync it with your smartphone via the FishSmart app. This way, you can benefit from smart notifications from your phone on the unit’s display, download charts, get software updates and more.

Along with the Ethernet and NMEA 2000 compatibility, the unit also has two microSD card slots. Therefore, you can use a charts card and a data card for recordings and backup simultaneously. This can be quite a plus as you won’t need to continuously swap cards if you need to use several.

The included mount for the unit is the standard Gimbal type, but an in-dash mounting kit is also available. A unit cover is not included.

The Pros

  • CHIRP Mega Side Imaging+ and regular CHIRP Side Imaging sonar;
  • CHIRP Mega Down Imaging+ and regular CHIRP Down Imaging sonar;
  • Dual Spectrum CHIRP sonar;
  • XM 9 HW MSI T transducer included;
  • Metallic transom mount for the transducer;
  • Depth capability up to 1,200 ft with the included transducer;
  • Multiple standard sonar features available, such as RTS, Bottom Lock, Selective Fish ID+, Alarms, SwitchFire etc;
  • Sonar Recording and Screen Snapshot functions;
  • Precision internal GPS;
  • Humminbird Basemap chart platform built-in;
  • AutoChart Live;
  • Supports Navionics+, Navionics Platinum, LakeMaster Plus, and SmartStrike charts;
  • Trackplotting, routes and waypoints functions;
  • 8″ display, 1024 x 600 resolution, 16-bit color display, with LED backlight, providing clear images, easy to read even in direct sunlight;
  • IPX7 waterproof;
  • Supports Ethernet and NMEA 2000;
  • Supports AIS and GPS heading sensors;
  • Supports CHIRP Radar and Minn Kota i-Pilot Link;
  • Bluetooth connectivity;
  • Compatible with the FishSmart App and the RC2 Bluetooth remote control;
  • Dual microSD card reader;
  • Upgradeable internal software;
  • Gimbal mount included;
  • Fairly easy to install.

The Cons

  • In-dash mounting kit is not included;
  • RC remote control is not included;
  • A unit cover is not included.


The Humminbird HELIX 8 CHIRP MEGA SI+ GPS G3N offers MEGA SI+, MEGA DI+ and 2D CHIRP sonar, GPS, and the Humminbird Basemap charts. It includes the XM 9 HW MSI T transom transducer. It also supports NMEA 2000, Ethernet, Radar, 360 Imaging, and more. It also has wireless connectivity. It’s a highly versatile fish finder and chartplotter, great for both inland and offshore fishing, perfect for a wide array of boats. Finally, although it’s not exactly the most affordable unit, it definitely offers excellent value for the price.

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