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Garmin echo 551dv

ProductDisplay SizeSonarDepthGPSCartography
echo 551dv
551 DownVü echo Garmin
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5"Dual Beam,
1900' DualBeam,
750' DI

Although the echo 551dv is a pretty much similar unit to the HELIX 5 DI from Humminbird, this particular Garmin unit does offer several different extra features, that’s why the price is currently a little bit higher. But in all, it’s a simple, small unit, made for anglers who only want sonar features. It’s a pretty affordable fish finder, currently available for less than $300.

Therefore, if you’re on the lookout for a sonar only fish finder, the echo 551dv is one unit that fits your needs perfectly.

Technical Details and Specifications

  • Screen: 5″ diagonal, 480H x 640V pixel resolution, VGA color, backlit
  • Sonar: Dual Frequency HD-ID, DownVü
  • Frequency and Coverage:
    • Standard view: 200 kHz / 15° and 77 kHz / 45°
    • DownVü: 455 kHz / 2.5° (fore to aft) x 53°
  • Depth Capability:
    • Standard: 1900 feet (579 m)
    • DownVü: 750 feet (228.6 m)
  • Transducer: GT20-TM (4-pin), for HD-ID and DownVü
  • Power Output: 500 Watts (RMS)
  • GPS: No
  • Maps: No
  • Routes, Waypoints, Tracklog: No

Sonar features and functions

For a small unit, this one is pretty powerful, offering a maximum depth capability of 1,900 ft in standard mode, and 750 ft. in Dv. Therefore, it’s great for rivers or lakes, but it can also serve you well on saltwater.

The Garmin echo 551dv comes with the 010-12087-00 transducer, which supports both standard and DownVü sonar technologies. In standard view, it can operate at two different frequencies with different beamwidths. As mentioned above, at 200 kHz you will benefit from a sharper sonar view, with a narrow angle of 15°, while at 77 kHz the angle is wider, covering more water, but with less accuracy. The narrow beam is great for shallow waters, while the wider beam is best to use for higher depths. Both standard sonar beams have circular cone pattern.

For DownVü, the transducer beam is fan-shaped, with a beamwidth of 2.5° fore to aft., and roughly 53° side-to-side. The images produced by the DownVü sonar are much sharper than the standard sonar view, offering photo-like quality, and the possibility to distinguish much better between structure and fish. It’s actually one of the best sonar features to have on such an inexpensive unit.

The transducer supplied with the unit, includes both transom and trolling motor mounts. Also, this unit supports 50/200 kHz, and several other types thru-hull, transom or trolling, from Airmar. The cable supplied with the transducer has a length of 20 ft. (6 m), long enough for just about any bass boat. But just in case you might be needing more cable, you can opt for an extension.

The transducer incorporates a temperature sensor, enabling the control unit to indicate water temperature. Also, one of the extra features this unit has over others in this price range, is a temperature graph function. As terminology suggests, this allows you to observe the variations of water temperature from a fishing spot to another, locate currents of various temperatures etc.

Along with everything mentioned so far, the echo 551dv does offer several other fish finding functions. Bottom lock is a function that allows you to select a certain distance span from the bottom, and the sonar will focus on the bottom maintaining the selected distance span, the image being possible to observe simultaneously with the normal sonar view. This function is great for looking for fish which feed near the bottom, or various structures where fish may hide.

A-Scope is a vertical flasher that appears on the right side of the sonar view, expanding the most recent sonar data to be easier to see. Speaking of flasher, this Garmin unit also provides an Ice Flasher view, great to use for ice fishing.

Needless to say, this unit does have a Fish Symbol ID function, which gives the sonar returns considered as fish, various fish symbols, along with the current depth of each one of them. This function is quite useful if you’re not familiar with the standard sonar view.

AutoGain is a noise filtering function that allows you to quickly change between maximum sonar info, and minimum clutter focusing on targets. It’s similar to the SwitchFire function offered by most Humminbird units. Split-Screen Zoom is also available, giving you the possibility to observe the standard sonar along with a magnified version of it, in split screen. This gives you a better view of the targets, and helps you understand better what’s their positioning in relation with other targets, the bottom and the boat.

Finally, the echo 551dv has sonar history rewind, giving you the possibility to scroll through the sonar feed, to review any spot you’ve recently sailed over.

Display unit features and functions

With regards to the display unit, it offers a rather small display, only 5-inch in diagonal. But the screen is backlit, supplying great readability in direct sunlight and during night fishing. The unit is IPX7 waterproof, meaning it can resists incidental water spills, rain etc. Note that it’s not full waterproof, therefore it’s best to avoit allowing it to be fully immersed in water, especially if it’s salt water.

For a small display, the 480 X 640 pixel matrix is just about enough to provide pretty sharp images. However, having 640H rather than vertically, would have provided more screen space for observing sonar in split screen. This is actually the only downside that can be mentioned regarding this unit.

It comes with a quick release swivel mount, but does not include screen cover. It’s compatible with just about any 12 volt battery, similar to the ones for cars, motorcycles and trucks. The unit can also indicate boat’s speed, however this requires an additional purchase of a speed sensor.


The echo 551dv Garmin is a decent and inexpensive fish finder. It supplies quite an array of sonar functions, actually offering several functions more than other similar units from various brands. On top of that, it provides one of the finest sonar technologies, DownVü. It’s a unit that will help you cut down the looking for fish by a lot, most definitely increasing your fish landing ratio.


  1. Unit as power but screen is dark. Tried using power button to increase back lighting but no change. Ideas??? Thanks

    • Backlight may be burnt.
      Unit may get the right voltage but not the amps due to a bad plug or weak connection inside the unit.
      In both cases it’s best to send the unit back and ask for a new one, especially if its still under warranty.

  2. what in hull transducers are compatible with this fishfinder?

    • Airmar P19 or Airmar P319. No DownVü thru-hull though, and these ones typically have an 8-pin plug, so you may need an 8-pin to 4-pin cable adapter.

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