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.

More pixels per square inch will provide better detail of structures, a better representation of what’s below you, and improved split-screen images. More pixels—higher screen resolution and a big screen—allow you to see the air bladders of smaller fish, see fish near the bottom, separate closely spaced targets from one another, and to see fish on the edges of “bait balls.” But remember: the contrast of the display must also be sharp in order to use the resolution. Like many features, you get what you pay for with display resolution—the more the better.

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.
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.

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.
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.
Look for equipment that will work with multiple frequency: higher for better detail but not as successful in deep water; lower for depth but less detail on your viewing screen. Of course, if you fish only in shallow water, you’ll be happier with high-frequency output. For deep-water work and for commercial fishing, you may want to use a lower frequency.
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.

A fishing line is a cord used or made for fishing. The earliest fishing lines were made from leaves or plant stalk (Parker 2002). Later lines were constructed from horse hair or silk thread, with catgut leaders. From the 1850s, modern industrial machinery was employed to fashion fishing lines in quantity. Most of these lines were made from linen or silk, and more rarely cotton.[3]


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.
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.
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.
Moreover, the 7SV also has a built in Garmin GPS that allows you to make your own waypoint maps, which makes marking all those stumps, docks, and brush piles as easy as clicking a button or two. All map information is transferrable to other Garmin fish finder devices if you upgrade as well, adding even more versatility to the 7SV. Additionally, the 7SV also has its own rechargeable battery pack that helps you stay on the water all day long, thereby increasing your chances of finally reeling in that trophy catch you’ve been looking for all these years.
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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