Active Sonar Fishing: What Is It & How Does It Work?
Intro
Have you considered buying an active sonar unit, but want to know more about how it works? Then this blog is just for you. We'll be going over the various specs and features from prominent commercial active sonar units and why they matter when you're on the water. Our video version of this blog post is above!
Active sonar units give anglers a live representation of the waters beneath them, so they can detect things such as: depth, depth changes, brush, floor hardness, fish, and any other objects in the water. It works by emitting an acoustic signal through the water. If the sound pulse reaches an object, it bounces back to the unit’s transducer and is relayed to your screen in real time.
Many active sonar features that are important to consider are: image quality, viewing modes, range, beamwidth, frequency, shallow water imaging, deep water imaging, and compatibility.
Image Quality
While some of your image quality hinges on its fishfinder’s display resolution (which we’ll go over later), certain sonar units produce more crisp images. Image quality is dependent on how well your unit does at taking the environment beneath you - and displaying it on your screen. You want to be able to accurately distinguish between fish, the environment, and other objects that may be in the water. Active sonar units often do a great job at discerning between things such as fish and brush. This is known as target separation. Additionally, seeing how your bait appears and how a fish may react is an added benefit of an active sonar unit with great image quality.
Viewing Modes
Next up are active sonar viewing modes. Active sonar units feature three viewing modes: front, down, and perspective. Each brand has a different name for perspective mode, but it’s the same concept. Forward-looking sonar maps the area in front of you, typically in an 18 or 20 degree cone, or field of view. Down-looking sonar keeps the same beamwidth as forward and is great for producing high-quality images at faster speeds. If you’re planning on covering a lot of water, downscan may be your best option. It’s also good for deep water imaging. Finally, perspective view gives a much wider view of what’s ahead, and it's best used in shallower waters, around 50 feet or less.
Range
An active sonar’s range can be important to some anglers, and meaningless to others. It depends on how you prefer to fish. Commercial sonar units have a range that varies between 150 and 200 feet. Naturally, objects feather in clarity the further they are from the transducer. A fish 100 feet away from your boat can not be detected as easily as a fish that’s 10 feet away.
Beamwidth
An active sonar unit’s beamwidth is it’s cone of view. Measured in degrees, the unit’s beamwidth appears like an elongated oval. Front and down-facing sonar scan shorter horizontally and longer vertically, while scout mode scans longer horizontally and shorter vertically. The beamwidth on active sonar units vary with each model, but are typically 20x135 degrees.
The active sonar unit’s frequency is very important, as it directly contributes to the clarity and crispness of the image. Higher frequencies unlock the ability to process more clear images on your fishfinder.
Shallow & Deep Water Imaging
Depending on how you fish, you may want to look into how an active sonar unit performs regarding shallow and deep water imaging. For example, Lowrance’s ActiveTarget is a great option for deep water imaging, especially considering their trolling motor head mount is angled further downward when compared to competitors. On the other hand, Garmin’s Livescope is an excellent choice (just in general) but especially for shallow water imaging. As we mentioned earlier, the further an object is from the transducer, the more difficult it is to accurately - and clearly - display the object on your fishfinder.
Shallow Water Imaging on Garmin Livescope
Compatibility
Compatibility is the last major feature we’ll be discussing. Each active sonar unit will be compatible with select fishfinders. Lowrance ActiveTarget is compatible with HDS LIVE, HDS Carbon and Elite FS fishfinder/chartplotters. Garmin LiveScope is compatible with EchoMap and GPSMap, while Humminbird MEGA Live is compatible with all APEX, Mega capable SOLIX, and all Gen 3/Gen 4 Mega HELIX models. Each fishfinder comes in different sizes, has different display resolutions, and customizable options. Some fishfinders even offer smartphone integration options, giving you the ability to connect to your display and do as you please!
Outro
Those are all of the key specs that are important with active sonar units. We discussed image quality, viewing modes, range, beamwidth, frequency, shallow water imaging, deep water imaging, and compatibility. These features are all very important when planning to purchase an active sonar unit and should be considered during the purchasing process. We sell all three mentioned sonar units here at Foothills Marine: give our Parts Department a call at 828-439-9022 to find out more information about how you can get your hands on one! Thanks for reading and we'll see you back at the Learning Hub!