While not every object will be as easy to distinguish, you can always get clues from the shape and also the strength of the sonar return. Notice the multiple orange sonar returns underneath the car – these tell you that this is a very hard object. The sonar scans have hit the car, bounced up to the surface of the water, bounced off the surface and hit the car again.
Ultrasound frequency used by a fish finder generally ranges from 15 kHz to 200 kHz. However, the majority of the conventional fish finders oriented for recreational craft utilize 50 kHz and 200 kHz. Such fish finders available in the market incorporate electronic circuitry that can transmit and receive ultrasound in these two frequencies. Also, a transducer mounted on the bottom of the craft is configured to handle these two frequencies.
Detection range (depth) of a fish finder depends upon the frequency used for ultrasound transmission. In principle, the higher the frequency of ultrasound, the shorter the propagation range can be. The wavelength of high frequency ultrasound is short, and its directivity angle is narrow, which enables detailed searches, but it attenuates significantly while travelling through water. Low frequency ultrasound is characterised by its long wavelength, wider directivity angle and high level of tolerance toward underwater attenuation, hence enabling wide-area-searches in deeper water. To summarize, you can choose low frequency if you are searching in deep water and high frequency if you are conducting a detailed search in shallow water. Further, when using low frequency ultrasound, you may be able to conduct more precise deep-water searches by adding an optional Power Adapter, which amplifies the transmitter power to a few kilowatts. Please note, however, that when using the Power Adapter, a dedicated transducer capable of handling higher transmitter power will be needed.
Fishing nets are meshes usually formed by knotting a relatively thin thread. Between 177 and 180 the Greek author Oppian wrote the Halieutica, a didactic poem about fishing. He described various means of fishing including the use of nets cast from boats, scoop nets held open by a hoop, and various traps "which work while their masters sleep". Ancient fishing nets used threads made from leaves, plant stalk and cocoon silk. They could be rough in design and material but some designs were amazingly close to designs we use today (Parker 2002). Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and are still used.
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.
It’s often been said that the act of fishing isn’t actually about catching a fish. Rather, it’s about a quiet moment with nature and a chance to sit, think and relax, whether on your bass fishing boat or on the banks of a river. Of course, if you’re a sport fisherman reeling in that prize monster on a white-capped ocean, there isn’t much relaxation to be had. If you prefer ice fishing or fly fishing, shop eBay for everything you need for a day on the water. We have the right gear for you, regardless of whether your allegiance lies with Orvis, Shimano or Abu Garcia.