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9"DualBeam Plus,
DualBeam Plus,

125' MEGA
SI & DI,

AC Live

The HELIX 9 CHIRP MEGA SI GPS G2N is one of the totally new units released for 2017 by Humminbird. As opposed to the last year’s HELIX 9 SI GPS, this unit features MEGA Side Imaging and MEGA Down Imaging sonar. The new MEGA Imaging delivers three times the output of regular SI and DI, using a scanning frequency of 1.2 MHz. Differently put, the images provided by MEGA SI and MEGA DI offer superior clarity and detail. Along with MEGA Imaging, this unit also features CHIRP sonar technology.

Technical Details and Specifications

  • Screen: 9″ diagonal, color TFT, 800H x 480V pixel resolution, 16-bit color, with backlight
  • Sonar: CHIRP MEGA Side Imaging, CHIRP MEGA Down Imaging, CHIRP DualBeam Plus with SwitchFire
  • Depth Capabilities:
    • DualBeam Plus: 1500 ft (457 m);
    • Side Imaging: 400 ft (122 m) at 455 kHz and 125 ft (38 m) at 1.2 MHz;
    • Down Imaging: 400 ft (122 m) at 455 kHz and 125 ft (38 m) at 1.2 MHz;
  • Frequency and Coverage:
    • DualBeam Plus: 200 kHz (175-225 kHz) / 20° and 83 kHz (75-95 kHz) / 60°
    • Side Imaging: 86°x2, 800 ft side-to-side coverage at 455 kHz, and 250 ft side-to-side coverage at 1.2 MHz
    • Down Imaging: 45° at 1.2 MHz, 75° at 455 kHz.
  • Transducer: Transom XM 9 20 MSI T
  • Power Output: 1000 Watts (RMS)
  • Power Input: 10.8-20 VDC
  • Power Draw: 2.5 AMP
  • GPS: Internal
  • Maps: Humminbird ContourXD (built-in)
  • Routes, Waypoints, Tracks: 47, 2,750, 50 (20,000 points each)

Sonar and transducer

The HELIX 9 CHIRP MEGA SI GPS G2N comes with a different transducer than the HELIX 7 CHIRP SI GPS G2N. The system includes the MEGA SI transducer XM 9 20 MSI T. This transducer integrates a temperature sensor and comes with a transom mount.

The unit itself is capable of using several scanning frequencies, including 50/83/200/455/800 kHz and 1.2 MHz. However, when using the DualBeam Plus (2D) standard mode, you won’t be able to use the 50 kHz frequency mode with this transducer. But nonetheless, the 83/200 kHz modes are available. For these frequencies, the transducer uses conical beams, of 20° (200 kHz) and 60° (83 kHz), being capable of scanning depths up to 1,500 ft (457 m). When CHIRP is enabled, the sonar pulse will be modulated on a frequency interval between 75-95 kHz instead of 83 kHz, and 175-225 kHz instead of 200 kHz, in order to supply superior images, with less clutter and a better separation between targets.

CHIRP MEGA Side Imaging

In terms of Side Imaging and Down Imaging, with the supplied transducer, the unit can use 455 kHz for regular mode, and 1.2 MHz for the MEGA mode. For regular Side Imaging (at 455 kHz), the transducer will use two thin lateral beams, with angles of 86°, able to extend up to 400 ft (122 m) on each side, with a total side-to-side coverage of 800 ft (244 m). For MEGA Side Imaging, the side beams will only extend up to 125 ft (38 m) on each side, 250 ft (76 m) in total. Also, if the CHIRP mode is enabled, the sonar pulse will be modulated in a frequency range between 420-520 kHz instead of a flat 455 kHz, and 1150-1275 kHz instead of a flat 1.2 MHz, evidently providing higher detail.

When it comes to Down Imaging, regular and MEGA modes are also available. When using regular DI, the sonar frequency used is 455 kHz, with a thin beam fore to aft wise, but with a coverage of 75°. In MEGA Down Imaging, the beam offers more focus but its coverage is only 45°. When CHIRP mode is activated the DI sonar will use the same pulse modulation as for SI.

CHIRP Down Imaging

The Side Imaging and Down Imaging depth capabilities of the unit are 400 ft (122 m) for 455 kHz, and 125 ft (38 m) for MEGA Imaging. As you can see, MEGA imaging cannot reach such great depths; however, it’s more than enough for most lakes. Also, if you’re going to use this system off-shore, and fish at depths greater than 400 ft (122 m), you’ll still have the DualBeam Plus sonar to rely on, which can reach depths up to 1,500 ft (457 m).

Quite an impressive array of fish finding functions, along with the MEGA Imaging modes, are available with this unit as well. Among them, we can count Selective Fish ID+, Real Time Sonar, SwitchFire, Sonar Recording, Screen Snap Shot, Circular Flasher, Fish Alarms etc. This unit is also 360 Imaging capable.


The HELIX 9 CHIRP MEGA SI GPS G2N features an internal precision GPS receiver, which delivers fast and accurate locks within 2.5 meters. Enhanced fixes are available, using information from WAAS, EGNOS or MSAS. Changing the GPS source to GLONASS is possible as well. The unit’s GPS system indicates latitude and longitude. It can also calculate and display the speed of your boat.

The unit can store 2,750 waypoints within its internal memory, and up to 47 routes (50 waypoints per route). It also features a trail recording function, being able to record and save up to 50 trails (20,000 points per trail). Trails can be converted to routes, though, and you also get the possibility to add waypoints to them if necessary.

The unit’s built-in charts package is the Humminbird ContourXD. These charts offer much more than the UniMap charts that come with the HELIX 5 and HELIX 7 units, covering more than 3,000 U.S. lake maps, with depth contour lines, channels, boat accesses, markers, major roads, and interstates. The navigation functions also include several other functions, such as Drift Alarm, Man over Board, Off Course Alarm, and a Bird’s Eye, 3D view for the maps.

But in case you’re not satisfied with the information and detail provided by the ContourXD charts, the good news is, the unit is compatible with various other charts, such as Navionics Platinum+, Navionics Gold/HotMaps, LakeMaster and SmartStrike fishing charts. It does not support C-MAP charts, though.

One of the best functions available with this unit, function with applications for both fishing and navigation, is AutoChart Live. This function uses the 2D sonar data and the GPS data in order to scan and draw the depth contours of the lake or reservoir where you’re fishing.

AC Live View

The unit itself can record up 8 hours of mapping, but if you equip the unit with a Zero Lines card, which is specifically designed to serve as support for AC Live, the unit’s recording possibilities will considerably increase. The AC Live requires LakeMaster or Navionics charts as a base for operation. Or, the ready-to-be-contoured charts from a Zero Lines card. Also, since this is a G2N unit, the AutoChart Live feature comes with two extra capabilities, these being vegetation and bottom-hardness mapping. In other words, it gives you the possibility to color code various parts of the lake or reservoir where you’re fishing, depending on the vegetation density or the structure of the bottom.

Last but not least, in terms of navigation, this Humminbird HELIX unit can support various external modules, including AIS, RADAR or i-Pilot Link.

Control unit features

Since this is a HELIX 9 unit, it’s equipped with a 9-inch display. Needless to say, its a color TFT display, with a 16-bit color range, and a pixel resolution of 800H x 480V. It integrates LED backlight, so it’s much easier to read regardless of weather, time of day, and regardless if you’re using polarized sunglasses. It’s also IPX7 waterproof, which means it can withstand incidental water exposure with no issues.

This unit uses standard button navigation. It doesn’t have touchscreen technology such as the ONIX8ci SI Combo. It does not have online connectivity such as other units, but it is, however, wireless control capable. It’s compatible with the Humminbird AS RC1 Bluetooth remote control, which features 7 dual-function keys, and gives you the possibility to control your unit from distance. Via this remote, you can mark waypoints, save a snapshot, adjust brightness, navigate through menus etc. This remote control is not included with the unit, though.

Just as the HELIX 7 CHIRP SI GPS G2N, this unit features an Ethernet port and an NMEA 0183 output, also being capable of NMEA 2000. Its microSD card reader has two card slots, an aspect that is quite a plus, as you can use two cards simultaneously, without swapping between them.

Last but not least, the unit comes with a standard gimbal mount, but an in-dash mounting kit is optionally available.

The Pros

  • MEGA Side Imaging and MEGA Down Imaging sonar;
  • DualBeam Plus sonar;
  • CHIRP sonar technology;
  • XM 9 20 MSI T transom transducer included;
  • Depth capability up to 1,500 ft with the included transducer, great for inland fishing, and even for shallow off-shore fishing;
  • Multiple sonar functions available, such as SwitchFire, Selective Fish ID+, Bottom Lock, Mark Structure, Real Time Sonar etc;
  • Sonar Recording and Screen Snapshot functions;
  • Temperature graph included;
  • Precision GPS with MSAS, EGNOS, and WAAS enhancing;
  • ContourXD charts included;
  • AutoChart Live with Bottom Hardness and Vegetation features;
  • Trackplotting, routes and waypoints functions;
  • 800 x 480 resolution, 16-bit color display, with LED backlight, providing clear images, easy to read even in direct sunlight;
  • AIS, i-Pilot Link, and Radar capable;
  • Bluetooth wireless control capable;
  • LakeMaster, Navionics, and SmartStrike charts capable;
  • Ethernet and NMEA 2000 ready;
  • IPX7 waterproof;
  • MicroSD card reader (2 slots);
  • Upgradeable internal software;
  • Gimbal mount included;
  • Unit cover included;
  • Fairly easy to install.

The Cons

  • Bluetooth remote control not included.


The Humminbird HELIX 9 CHIRP MEGA SI GPS G2N is fish finder and chartplotter system, featuring MEGA Side Imaging and MEGA Down Imaging sonar, along with CHIRP technology. The system includes the required transducer for these types of sonar. It also has excellent navigation functions including a fast and accurate GPS system, the ContourXD charts, and the AC Live function. It’s a unit great for off-shore and inland fishing. It’s not exactly an affordable unit, but considering its superior sonar and excellent range of navigation features, we can safely say that its value stands up to the price.


  1. I’m almost positive that Helix 9s come with a unit cover. I have the Helix 9 g2N DI unit up front in my boat, and it came with a unit cover. I’m pretty sure the 9, 10, and 12s have Unit Covers. They are sold separately with the 5 and 7s.

    As a result, the lack of a unit cover should not be listed under CONs.

    • Indeed. It comes with a unit cover. Fixed 🙂

  2. Can this unit be hooked together with the 998c in sequence

    • They should work. There’s a networking chart for the Humminbird products on their site. Found it here:

  3. all that networking gets outrageously expensive. I assume its all NMEA connections? Thanks for a great review by the way—one other question, how physically large is that transducer that the helix 9 and 10 mega comes with? do you see any advantage to pay an additional 400$ for the same feature but the helix 10? Is it only 1″ larger screen? thx

    • The dimensions of the XM 9 20 MSI T (the one that comes with the HELIX 9) are 9.6″L x 2″W x 6.5″H; couldn’t find the exact dimensions for the XM 14 20 MSI T (the one that comes with the HELIX 10), but should be approx. the same.

      The HELIX 10 not only that has 1″ extra on its diagonal, it also has a higher resolution (1024 x 600) than the HELIX 9 (800 x 480). So, more pixels, higher definition, better imaging. However, 400$ is quite a bit more. I think I’d rather go for the HELIX 9 CHIRP MEGA SI GPS G2N here.

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