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]
A fish finder is a sonar instrument that is designed for the specific purpose of detecting fish underwater. It does so by detecting reflected impulses of sounds energy. All the electronic impulses that are reflected off fish are converted into information that is then display in graphic rendition on the screen of the fish finder. In addition to locating fish, these units also measure the depth of the water, locating underwater debris, and bottom structure. The image on the screen of the fish finder can represent just one fish in the form of a small icon or with a series of arches.
Power output is measure in watts, often represented by the “W” symbol. With more power you’ll get clearer, more-accurate readings, and you’ll be able to find fish in deeper water. Units with limited power won’t always send the signal out far enough and you can get poor quality images. Look closely for a good power output and frequency options. The right combination can help you choose the right unit, based on overall ability. You’re looking for balance of depth, power and clarity of image.
The thickness of the line representing the bottom is also a great clue to bottom hardness. Here the rule is simple – the thicker the line, the harder the bottom. But, be careful – sonar sensitivity can affect how thick the line is. The Deeper display has adjustable sensitivity. So if you turn up the sensitivity to 100%, the bottom line may appear thicker, if you turn it down to 10% it may appear thinner. So practice adjusting the sensitivity and get used to judging how much the bottom thickness varies based on this.
Search our Knowledge Base for frequently asked questions, register your product warranty, download a product manual, or share your feature suggestions with us. If you can not find what you are looking for in the Knowledge Base, create your own topic, or email us and we will create a priority service ticket for you. Need instant help, try the chat button or the vertical tab on the right side of the screen on any page. Register your HawkEye Warranty

Create memorable fishing experiences with the incredible selection of equipment and accessories at Academy. From rods, reels, and baits to storage, care, and apparel, we have fishing gear you need to stay prepared. Facing unpredictable weather or getting up close in the water? Shop our assortment of apparel and waders that will help keep you dry and comfortable. Go high-tech with various fish-finding equipment that can help you track and secure the best catch. We also offer practical fishing equipment like lights, fish processing tools, nets, baskets, grippers, bait traps, and other miscellaneous tools you'll want on hand. Whether you're a casual fisher or an avid adventurer, you'll be able to find the exact things you need to make the most of your fishing expedition. Create the best memories with family and friends, or take to the great outdoors by yourself. No matter your fishing style, there's something for you. Shop our diverse collection today to find high-quality products from brands you can trust.
×