In operation, an electrical impulse from a transmitter is converted into a sound wave by an underwater transducer, called a hydrophone, and sent into the water.[3] When the wave strikes something such as a fish, it is reflected back and displays size, composition, and shape of the object. The exact extent of what can be discerned depends on the frequency and power of the pulse transmitted. Knowing the speed of the wave in the water, the distance to the object that reflected the wave can be determined. The speed of sound through the water column depends on the temperature, salinity and pressure (depth). This is approximately c = 1404.85 + 4.618T - 0.0523T2 + 1.25S + 0.017D (where c = sound speed (m/s), T = temperature (degrees Celsius), S = salinity (per mille) and D = depth).[4] Typical values used by commercial fish finders are 4921 ft/s (1500 m/s) in seawater and 4800 ft/s (1463 m/s) in freshwater.
It terms of the functionality, the HDS-7 is able to connect to the internet to broadcast data, update to new software, upload information such as marked coordinates and more. This Lowrance model uses the latest of advanced technologies such as CHIRP sonar, Broadband sounder, StructureScan HD, DownScan imaging and Trackback view for the ultimate fish finding experience.

Now let’s imagine another scenario – again your sonar is stationary, but this time 2 fish swim through your sonar beam, one big and one small. The big fish swims very quickly through the sonar beam, the small one swims slowly. Which one will make the longer fish arch on your screen? The answer is the small one. That’s because a slow moving object will leave a longer mark than a fast moving one, whatever their size.


You have been anxiously awaiting the arrival of the weekend so that you can pack up and hit your favorite fishing area. You dream of landing your next big catch, and a fish finder is just what you need to help you locate the ultimate fishing spot. If you love spending time in the great outdoors, then you can find just what you need to get ready for your next adventure. On eBay, you can browse through a large selection of fish finders in both new and refurbished conditions, available from trusted and reliable sellers. The Hummingbird fish finder can easily be attached to any surface on your boat and can aid you in discovering where the fish are hanging out. If you do not enjoy fishing yourself, but are looking for something to get the outdoorsman in your life, a portable fish finder is a perfect gift and sure to bring a smile. Shop easily online, check out convenient shipping options, and reel in an amazing deal on the perfect fish finder.
A fish finder is an incredible tool that can help take your sport or commercial fishing venture to the next level. However, even the best fish finders can use a little improvement – and adding a GPS is one way to do this.The best fishfinder GPS combo will help you navigate whatever body of water you are on at the same time as it allows you to find where to fish more quickly, accurately and efficiently.
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.
You probably already know how to use a Garmin chartplotter. It is that intuitive. Just turn it on and you can quickly follow the simple menu. Everything is at your fingertips to quickly and easily plan your route and set your course. And most Garmin echoMAP™ and GPSMAP® chartplotters are available combined with built-in sonar capabilities. These include advanced HD-ID™ sonar, CHIRP sonar and Garmin ClearVü™ and SideVü™ scanning sonar, which provides the clearest scanning sonar images on the water.
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.
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.

Lowrance hds 7 gen 2 touch. Took it off my boat when I got low balled on price of boat.... I think it has less the an hour on it... I honestly dont remember using it at all. Regardless, it has very very low hours if it was used at all. No ducer, wire or mounts come with this. Buyer of my boat literally handed me cash that was 500.00 short so I took it, unplugged this and walked away. Perfect for someone that already has lowrance set up on boat. Selling with no reserve. So good luck.
It changed the game once. Now it’s poised to do it again. The HELIX Series has evolved, now offering MEGA Imaging+, Dual Spectrum CHIRP and Bluetooth connectivity in select models, along with exclusive technologies like Humminbird Basemap that you won't get from any other fish finder in its class. Power. Bold styling. Ease of use. In this family, the apple doesn’t fall far from the tree.
There is a huge variety of fish finder brands, their models and types. All this can make it quite complicated and time consuming to find the right one for your needs.  To help you in your search, we have compiled this best fish finder reviews of the models that are popular and top rated in 2017. With our reviews you can find the right fish finder for your style of fishing. To make sure that you get the right features for your needs, it’s important to do prior research. So read our reviews and comparisons to decide which model you need.
Our Depth Sounders are designed to mount flush in the dash of your boat. Our friendly user interface, automatic range & sensitivity and proprietary algorithms produce precise readings at speeds in excess of 60 MPH. Say goodbye to the days of not knowing the depth while running your boat on plane. Our Hand Held Depth Finders takes portable sonar systems to a whole new level. Get precise readings on the go with just a press of a button.
In summer and winter, water temperature is very important - these units will help you discover areas that should be comfortable for your target species. Safety is found in structure, for prey and predator alike. The illusion of safety for baitfish equates to food for prey. So locating proper structure is certainly important. It's been said that 90% of the fish can be found in 10% of the water. Believe it. If you're fishing structure in the middle of a lake or a man-made reef, knowing what's below you is important. Now you know.
Standalone fishfinder: If you just want to see what’s below, dedicated fishfinders give the biggest display and the most performance for the least cost. If you have a small boat that you use for fishing small inland lakes or are on a limited budget, a standalone fishfinder is for you. Conversely, if your pilothouse has room for multiple displays, or if you just bought a new GPS, get a serious big-screen fishfinder. You can usually add a GPS sensor later to many units, turning them into chartplotter combos.
Eventually, CRTs were married with a fathometer for commercial fishing and the fishfinder was born. With the advent of large LCD arrays, the high power requirements of a CRT gave way to the LCD in the early 1990s and fishfinding fathometers reached the sporting markets. Nowadays, many fishfinders available for hobby fishers have color LCD screens, built-in GPS, charting capabilities, and come bundled with transducers.[5] Today, sporting fishfinders lack only the permanent record of the big ship navigational fathometer, and that is available in high end units that can use the ubiquitous computer to store that record as well.
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.
Fish finders are incredibly valuable tools, and the more you learn about how to read them, the more successful your fishing trips will be. A key part of learning as angler is to go from trial and error to a more knowledge-based approach. Maybe you regularly catch at a certain spot with a certain presentation – but do you know why? A fish finder will help you understand not just your failures, but also your successes. And once you know this, you can recreate this success more easily.
It’s no secret that HDS displays are used by more tournament fishing pros than all other fishfinding brands combined, so we didn’t have to go back to the drawing board to build it; we just made the best fishfinder/chartplotter in the world even better. HDS LIVE  delivers premium performance and support for the best collection of innovative sonar features available – from Active Imaging™, StructureScan® 3D, FishReveal™ and LiveSight™ sonar, to exciting navigation functionality like C-MAP® Genesis Live mapping – all designed to help you find more fish.
A GPS also gives you navigation through the waters. For this you will need to select a unit that comes with background maps and charts. One more benefit of the addition of the GPS is safety. Wherever you fish, you will have the confidence that at the end of the day the GPS will easily point you home. For example, you could be fishing throughout different locations during the day, or you could lose sight of land, or some severe weather could suddenly roll out. In such situations, a GPS will give you the exact direction to your home and will tell you how far it is.
These are very valuable features to target for a range of species, and the good news is, they are easy to spot with a fish finder. As you troll or reel in your device, you will see the depth contour change – don’t forget to use the depth reader on your display (on the Deeper App it’s in the top right corner of the screen) so you can track how quickly the depth is rising or falling.
It’s no secret that HDS displays are used by more tournament fishing pros than all other fishfinding brands combined, so we didn’t have to go back to the drawing board to build it; we just made the best fishfinder/chartplotter in the world even better. HDS LIVE  delivers premium performance and support for the best collection of innovative sonar features available – from Active Imaging™, StructureScan® 3D, FishReveal™ and LiveSight™ sonar, to exciting navigation functionality like C-MAP® Genesis Live mapping – all designed to help you find more fish.

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Important parameters of a fishing line are its breaking strength and its diameter (thicker, sturdier lines are more visible to fish). Factors that may determine what line an angler chooses for a given fishing environment include breaking strength, diameter,castability, buoyancy, stretch, color, knot strength, UV resistance, limpness, abrasion resistance, and visibility.
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