Due to my location a fish finder with gps/chart plotter wouldn't be of much use as there are few maps and fewer sonar charts available so I decided on a non gps fish finder. I checked the local budget marine store where they have live display models running the sonar simulations on display and the echo DV 551 stood out from the similar priced units with a sharper 640x480 display that was very viewable in daylight.

The sonar has basically the same features of same class lowrance and humming bird models and supports 50/77/200 kHz plus the 455/800 kHz for down scan imaging with the included transducer but at the time was on sale for $260 bucks! Which is a lot less than other 5" models with or without gps, sold!

In the water the down scan worked but you needed to adjust the contrast and colour settings to see real detail on the bottom, in split screen with traditional sonar you can see the fish icons very well on a typical kayak install ( ie far up front ) so I turned them off and set alarms which in the real world you can barely hear with your paddle splashing and near by motor craft moving around. I don't see any volume adjustments in the menu or manual and I want my eyes out of the kayak looking for surface action or birds not glued to the sonar screen..

Other than that the sonar worked as it should, easily spotting fish as they passed by and my jigs in down scan , it's splash proof and easily removed from its cradle which made installation easy, at least in my lure's sonar pod as it comes with all needed hardware in stainless at that, just add a battery and go.

Just don't expect to add any gps features for it, I will use my hand held for that