The image above, at right, clearly shows the bottom structure—plants, sediments and hard bottom are discernible on sonar plots of sufficiently high power and appropriate frequency. Slightly more than halfway up from the bottom to the left of the screen centre and about a third away from the left side, this image is also displaying a fish – a light spot just to the right of a 'glare' splash from the camera's flashbulb. The X-axis of the image represents time, oldest (and behind the soundhead) to the left, most recent bottom (and current location) on the right; thus the fish is now well behind the transducer, and the vessel is now passing over a dip in the ocean floor or has just left it behind. The resulting distortion depends on both the speed of the vessel and how often the image is updated by the echo sounder.

A compact, affordable combination GPS/Fishfinder. Simrad’s GO 5XSE is an all in one solution to quality chartplotting and sonar. The included Med/High/DownScan transducer provides exceptional sonar imaging in near-photo like detail. Multiple Charting options from Insight, Navionics and C-Map enable the Simrad GO5 to go anywhere the water takes you.
The final point to remember when you are looking out for fish arches is that it doesn’t need to be a full arch. Half arches (like the ones shown in the screen shot above) also show that there is fish. In ourtutorial on how sonars work, we explain in detail why sometimes you get a full arch and sometimes you get a half arch. The short answer is that you will get a full arch if a fish swims through the whole of your sonar cone, and a half or partial arch if they only swim through part of it.
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While many fish finders point directly underneath your boat, higher end units like this one will sweep to the sides as well. Considering that you are casting out from the ship rather than dangling lines beneath it, side sweeping is much more valuable as it allows you to find fish wherever you are, rather than finding them, moving the boat, and then trying to catch them.
Transducers: Fishfinders operate using a single frequency transducer, dual frequencies, multiple frequencies or a broadband CHIRP system. In general, higher frequencies give the finest detail resolution, the least background noise on your screen and the best view from a fast-moving boat, but don’t penetrate as deeply as lower frequencies. Shallow-water inland anglers generally choose higher frequencies of 200kHz, 455kHz or 800kHz. For maximum depth, use lower frequencies. We recommend 200kHz or higher (up to 800kHz) for water depths up to 200' and 80kHz or 50kHz for deeper waters.
Explore our collection of new fly-fishing gear and equipment. We carefully plan our designs and research every detail so you can maximize your fishing time and enjoy the best fishing gear money can buy. Discover the latest in a variety of fishing gear, including fly rods, fishing packs, waders, boats, wading boots, fly reels, and other gear. Let us help prepare you for your next fishing adventure—our selection of fishing gear has been engineered and tested by industry professionals to bring you only the best fishing products; shop with confidence knowing you're choosing from the best fly-fishing gear on the market.
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]

We’re only slightly kidding when we say that one of the simplest ways to pick a transducer is to decide just how big of a hole you want to drill in your boat. Fishfinders intended for the small-boat, freshwater angler often come with a transducer, usually a transom-mount type. But many transducers are purchased separately and need to be installed through the hull.
Big baits catch big fish, but this presents a problem for the ice angler. Hunting behemoth pike and muskies requires large, lively baits that do not play nice with tip-ups. Suckers and live trout are strong enough to trip the flag of almost any tip-up, causing you to waste time resetting lines after false alarms. Attaching a planer board clip to your tip-up to hold your main line will prevent even an 18-inch sucker from triggering a false flag. The added pressure of the clip, which can be adjusted, has enough tension to hold suckers and trout but still allow predators to pull the line free and run. The flag will trip when it matters, but the bait won’t have the strength to trip it by itself. Just snap the clip to the line guide of the tip-up under the spool. This will allow the planer board clip to hang freely under the water. Simply clip in the main line after setting the bait.
For precise detection of structures and fish, our Raymarine radar bundle gives you remarkable resolution. The Garmin Chartplotter radar combo updates your position 10 times per second to accurately maintain your heading. A large screen with an outstanding LED display on our Humminbird fish finder GPS provides images that are easy to read even in bright sunny conditions. You can find the best marine depth finder GPS combo here, and we stand behind all of our products with a 30-day guarantee against defects. Contact our team of experts if you should need any assistance in finding the products you require.
LCD displays are made of a grid of “picture elements,” tiny dots that individually darken when electrical current is applied, with their name shortened in common usage to “pixel.” More vertical pixels mean higher depth resolution, as each pixel represents less depth. The number of pixels in a screen’s horizontal axis determines how long objects stay onscreen before they scroll out of view, of significant importance with split-screen displays showing narrow columns of side-by-side information.
GARMIN ECHOMAP 73SV FISH FINDER LIKE NEW CONDITION. Condition is Used. comes with everything in the box as new except the mounting screws for transducer, I only used this for about 1 year, then went to a garmin echo plus chirp unit, everything works like new , has original box, I know the transducer alone will sell for $200-249 alone when new any questions feel free to email me!
As with many products, you’ll have to pay close attention to the specific features delivered for the price, simply because the investment for combination fishfinder and GPS can range from $500 to $1200 or more. Fishfinders and GPS units are well advanced when compared to equipment used just a few years ago. Most of the time you can get excellent 3D mapping, scanning, charting and navigation at a very reasonable price. It’s not necessary to spend hundreds more unless you really want to go after the top-of-the-line unit.
The depth scale on the right of the screen enables you to identify the depth of any features you find. The depth reading in the top right of the screen shows you the bottom depth under your fish finder right now – bear in mind this is not necessarily the same depth as the features you have just scanned, especially if you are scanning drop offs or points.
The image to the right shows a school of white bass aggressively feeding on a school of threadfin shad. Note the school of baitfish near the bottom. When threatened, baitfish form a tightly packed school, as the individuals seek safety in the center of the school. This typically looks like an irregularly shaped ball or thumbprint on the fishfinder screen. When no predators are nearby, a school of baitfish frequently appears as a thin horizontal line across the screen, at the depth where the temperature and oxygen levels are optimal. The nearly-vertical lines near the right edge of the screen show the path of fishing lures falling to the bottom.
Just getting started using a fish finder? Know the basics but want to get more out of your fish finder? Not sure you’re reading your fish finder display correctly? Don’t worry, we’re here to help. This short tutorial will teach you how to make sense of your fish finder display so you can tell what’s a bait fish, what’s a trophy catch and what’s just a submerged tree that you’ll snag on. Take just 7 minutes to go through this tutorial and at the end you’ll be able to read your fish finder display for:
The size of the area you’re scanning will be affected by the angle of the cone. A wide beam cone scans between 40°-60°, meaning you’ll be covering a large area. A narrow cone will scan between 10°-20°. So make sure you’re aware of whether your fish finder is using a wide or narrow cone when you’re looking at the data on your screen. The Deeper PRO and PRO+ have wide and narrow beam scanning (55° and 15°), the Deeper START has a medium/wide beam (40°). One other point to remember about how you sonar works is that it is constantly sending and receiving data, which means your display will be continually scrolling. The current scanning data will be on the right – the further left on the screen, the older the data.
Bait: If you're not using live bait or cut bait, you'll want to use artificial bait or lures. Most artificial lures resemble the type of bait fish or other food, such as worms or shrimp, that the fish you're trying to catch normally eat. These artificial baits can be scented and have metal spoons attached to them or be painted in metal flake to reflect light in the water. Other types of bait include jigs and jig heads, spoons, flies and spinnerbaits, which you can attach artificial or real bait to, and attractants to make artificial lures smell lifelike.
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