Understanding how a fish finder works will help you to understand how to use it. Fish finders work using sonar. It’s a technology that uses sound waves to display underwater objects. The fish finder produces the sound wave and with the transducer sends it through the water. Penetrating the water deeper, the sound wave starts to spread in the form of a cone (commonly called a beam). As the wave encounters objects within this beam, it sends the signal back to the transducer.
The Garmin Echo 551DV is one of the newer and more advanced models in the Garmin line of fish finders and it’s the top fish finder under 300. It’s one of my top choices and I really think that it’s the best fish finder for the money. It offers the best fishing sonar and a large clear display. The transducer has 500 watts of power, which allows the wave to go as deep as 2300 feet. It comes from the echo fish finder series that are known for their great accuracy.
Raymarine’s DragonFly 4 PRO with Navionics Plus Mapping offers Dual-Channel Sonar with CHIRP DownView enabling easy identification of fish and underwater structure with photo-like images. Reaching depths of 600ft with CHIRP DownVision and 900ft with CHIRP Sonar the DragonFly 4 includes a built in GPS receiver and provides accurate coastal navigation data all on a 4.3” Color Display.
Whether it is radically changing the way you enjoy your favorite pastime with our game changing marine technology, or reinventing our current product line, we relentlessly pursue innovation in all aspects of our business. At NorCross, Customer Focused Innovation is not just some fancy corporate slogan, it is the foundation of every product and service that we offer. We strive to keep our marine electronics exactly what you need whether that is on the shoreline or in your kayak.

Detection range (depth) of a fish finder depends upon the frequency used for ultrasound transmission. In principle, the higher the frequency of ultrasound, the shorter the propagation range can be. The wavelength of high frequency ultrasound is short, and its directivity angle is narrow, which enables detailed searches, but it attenuates significantly while travelling through water. Low frequency ultrasound is characterised by its long wavelength, wider directivity angle and high level of tolerance toward underwater attenuation, hence enabling wide-area-searches in deeper water. To summarize, you can choose low frequency if you are searching in deep water and high frequency if you are conducting a detailed search in shallow water. Further, when using low frequency ultrasound, you may be able to conduct more precise deep-water searches by adding an optional Power Adapter, which amplifies the transmitter power to a few kilowatts. Please note, however, that when using the Power Adapter, a dedicated transducer capable of handling higher transmitter power will be needed.
Fish icons are a useful tool when you are getting started with a sonar device: your fish finder interprets the sonar data it receives and tries to work out if it is a fish or not. It does this based on factors like the size of the object and the strength of the sonar return. In the case of Deeper sonars, we use an advanced algorithm in the Deeper App to interpret the data. Unfortunately, even the most advanced units aren’t 100% accurate in interpreting correctly.

The intensity of the sonar return from a hard bottom will be different to one from a hard bottom. Your fish finder uses colour to show this difference. In the standard colour palette of the Deeper display, the colour varies from dull brown (softest) to intense orange (hardest). In the day mode colour palette (see screen shot), the difference is even easier to see, with the colour ranging from purple (softest) to red to orange to yellow (hardest).
Fish finders were derived from fathometers, active sonar instruments used for navigation and safety to determine the depth of water.[1] The fathom is a unit of water depth, from which the instrument gets its name. The fathometer is an echo sounding system for measurement of water depth. A fathometer will display water depth and can make an automatic permanent record of measurements. Since both fathometers and fishfinders work the same way, and use similar frequencies and can detect both the bottom and fish, the instruments have merged.[2]
Once you've got your rod and reel setup how you want it, pull the right fishing line and tackle for the waters you're fishing from your tackle box and get to work. Add a sinker for more depth or a floater that can help track your line. A thick fishing line and hook will provide more resistance for reeling in larger fish. If nothing's biting from the shore, why not load up your fishing tools into a fishing boat or raft and try exploring further out. Customize the power of your boat with a trolling motor or do things the old fashioned way with a canoe and paddles.
The Axiom 9RV from Raymarine is a top of the line 9” Multi-Function Display with RealVision Sonar and comes packed with an RV-100 Transom Mount Transducer. The included RV transducer will provide CHIRP DownVision, CHIRP SideVision, High Frequency CHIRP and RealVision 3D all in one. Detailed U.S and Canadian Mapping for Coastal and Lake water is also included with Navionics+ Mapping.
Finally, we come to the HDS-7 from Lowrance. I have had limited experience with this company, but from what I know it is a fantastic maker of fish finders, and the HDS-7 is no exception. This particular model has a seven-inch touchscreen, which makes it one of the most high-tech options you can find anywhere. If you like a more ergonomic design and want something that is more user-friendly, the HDS-7 could be for you.
Shipping is always free for parts and accessories for all our Marine Electronics. We have just about any replacement part that you would need to repair your HawkEye product, and a vast amount of marine accessories to customize your boating and fishing experience. Whether you are looking into our cable float kit or replacement lens for your hand held depth sounder, we have it all.
Whether you're an experienced fisherman with boating experience or a beginner casting from the shore, eBay has the gear you need. Once you have the rods, the rompers and the boat, you still need fishing hooks, lures and tackle boxes. eBay has a great selection of fishing gear for sale. Browse spinning reels, rod and reel combos, fishing line, tackle boxes and rod cases. Whether it’s Okuma or Rapala, hook removers or baitcasting fishing reels, there’s no need to trek to the outdoor warehouse to peruse rows and rows of fishing products. With easy-to-navigate categories and plenty of options, eBay’s online fishing shop offers everything you need to head out to sea or into the quiet creek for the catch of your choice. Check out eBay's lures section to find the soft bait and hard bait that you're looking for. You’ll also find marine electronics like fishfinders—whatever it takes to help make that elusive prize catch. And if you’re in the market for a trolling motor, you’ll find that here as well, and at a great price.