CHIRP devices can transmit simultaneously on high and low frequencies. The lower frequency gives greater depth penetration, and it requires less power than a higher frequency signal so it generates less noise. The result is a “whisper into the water” that locates the fish without disturbing them. The higher frequency signal gives even finer detail at shallow to mid-water depths.
Commercial and naval fathometers of yesteryear used a strip chart recorder where an advancing roll of paper was marked by a stylus to make a permanent copy of the depth, usually with some means of also recording time (Each mark or time 'tic' is proportional to distance traveled) so that the strip charts could be readily compared to navigation charts and maneuvering logs (speed changes). Much of the world's ocean depths have been mapped using such recording strips. Fathometers of this type usually offered multiple (chart advance) speed settings, and sometimes, multiple frequencies as well. (Deep Ocean—Low Frequency carries better, Shallows—high frequency shows smaller structures (like fish, submerged reefs, wrecks, or other bottom composition features of interest.) At high frequency settings, high chart speeds, such fathometers give a picture of the bottom and any intervening large or schooling fish that can be related to position. Fathometers of the constant recording type are still mandated for all large vessels (100+ tons displacement) in restricted waters (i.e. generally, within 15 miles (24 km) of land).
The display is all about pixels. With more pixels you will be able to see more details, so it’s also an important factor to consider. More pixels also means higher price of the fish detector. We would suggest going minimum 240(v) x 160(h) pixels of the screen. However, this screen will give a pretty blocky image. To have a sharper image and better resolution, you will need to invest more.
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.
However, fish finders for professional use, i.e., those used by commercial fishermen, can make use of other frequencies. Such frequencies include 15, 22, 28, 38, 45, 50, 68, 75, 88, 107, 150 and 200 kHz. There are some special fish finders that utilize the frequency of 400 kHz, but it is quite a rare case. As you can see, there is an extensive range of configurable frequencies available for fish finders for fishery vessels, and a fish finder generally makes use of a combination of two frequencies (high and low frequencies). The selection of the frequencies depends upon the intended purposes of the fish finder, which include, inter alia, finding specific fish species; grasping the seabed condition; conducting a wide-area-search with the search angle of 90 degrees at one go; conducting detailed search for fish schools; detecting fish schools that give weak echo returns; avoiding interference/conflict with other fish finders used nearby. The searchable range (depth) and search area are dependent upon the frequency used. On the one hand, high frequency ultrasound is suitable for a detailed search, although it cannot be used for search in deep water. Low frequency ultrasound, on the other hand, is suited for general searches in a wider area as well as searching in deep water.

There is not much that is more relaxing than spending a beautiful day out fishing in your boat. One thing that may make the day even better is a fish finder GPS, so you do not go home without some delicious fish for dinner. On eBay, reliable sellers offer a broad range of new and used fish finders for you to choose from, including brands like Garmin, Lowrance, Eagle, and Hummingbird. With your new color GPS fish finder, you can enjoy a full color display, along with features that may include screenshots, fish and depth alarms, zoom, and dual imaging. The Garmin 546S Marine GPS find finder, for example, features a chart plotter, sonar, an anchor alarm, sunrise and sunset calculator, and marine cartography software included. No matter which fish finder GPS you decide upon, feel confident that you are receiving high-quality products and convenient shipping options that will ensure that your order makes it to you quickly.
Overall, if you want to get the best fish finder, then our top pick has to be either the Humminbird Helix 7 or the Garmin Striker 7SV. We love the large screens and comprehensive functions that you get with both devices, as well as the rugged dependability. If you want to save money, though, the Garmin Striker 4cv will be your next best bet as it comes with high-performance results, even with a smaller screen.
By calculating the amount of time between when the sound wave was sent and when it bounced back, it measures the distance and shows it on the screen. If the wave doesn’t encounter anything on its way, it reaches the bottom. If the bottom is soft and it’s just mud and weeds, the signal gets absorbed. A rock bottom will reflect a stronger signal back.
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.
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.

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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.
There are a lot of good reasons to make sure your fish finder has GPS built into it, with the biggest being improving your fishing techniques and mapping all the data you could want as a fisherman. Each of these options have some great benefits to them, so pick the one that is in the right price range for you! A good rule of thumb is the more you pay, the better mapping options you are going to get, so please remember this if that is an important feature for you!
There are a lot of good reasons to make sure your fish finder has GPS built into it, with the biggest being improving your fishing techniques and mapping all the data you could want as a fisherman. Each of these options have some great benefits to them, so pick the one that is in the right price range for you! A good rule of thumb is the more you pay, the better mapping options you are going to get, so please remember this if that is an important feature for you!
Fishing tackle boxes have for many years been an essential part of the anglers equipment. Fishing tackle boxes were originally made of wood or wicker and eventually some metal fishing tackle boxes were manufactured. The first plastic fishing tackle boxes were manufactured by Plano in response to the need for a product that didn't rust. Early plastic fishing tackle boxes were similar to tool boxes but soon evolved into the hip roof cantilever tackle boxes with numerous small trays for small tackle. These types of tackle boxes are still available today but they have the disadvantage that small tackle gets mixed up. Fishing tackle boxes have also been manufactured so the drawers themselves become small storage boxes, each with their own lids. This prevents small tackle from mixing, and can turn each drawer into a stand-alone container which can be used to carry small tackle to a rod some distance from the main tackle box.
The Garmin Striker 4 has all the features that one may desire when acquiring a fish finder and its low price makes it perhaps the best fish finder with GPS one is likely to find in the market. The advanced technology installed in the device will make the days one used to persevere without knowing whether they are going to catch anything seem outdated and very undesirable.

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.
These units are battery operated and the signal is transmitted back to the receiver. So, don't expect a lot of range or HD resolution. But, if you simply want to know how deep the water is ahead of you so that you can make better choices, this is it. For me, I would need to cast it with a rod/reel loaded with heavy braid. The areas I'd likely cast to would hopefully hold big snook and in the spring they love this color. I don't want the "dog ate my homework" story to become the "snook ate my transducer" story.
The most common mistake anglers make when reading their fish finder is thinking that a long arch means a big fish. This is not the case. On your sonar display, you should think of length as representing time. For example, imagine you keep your fish finder stationary in the water (in other words you are not reeling or trolling it). If there is a fish underneath that is also stationary, what will you see on your fish finder display? You will see one continuous line. That doesn’t mean there’s a blue whale stranded in the pond you’re fishing. It means there is a stationary fish under your fish finder, and it might be a very small one.
A sinker or plummet is a weight used when angling to force the lure or bait to sink more rapidly or to increase the distance that it may be cast. The ordinary plain sinker is traditionally made of lead. It can be practically any shape, and is often shaped round like a pipe-stem, with a swelling in the middle. However, the use of smaller lead based fishing sinkers has now been banned in the UK, Canada and some states in the USA,[4] since lead can cause toxic lead poisoning if ingested. There are loops of brass wire on either end of the sinker to attach the line. Weights can range from a quarter of an ounce for trout fishing up to a couple of pounds or more for sea bass and menhaden.
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