User manual RAYMARINE APELCO 465 FISHFINDER

[. . . ] Distributed by Any reference to Raytheon or RTN in this manual should be interpreted as Raymarine. The names Raytheon and RTN are owned by the Raytheon Company. Echo Sounding How it Works x Your eyes underwater An "echo sounder" or "sonar" unit sends high-frequency sound waves down into the water below a boat. These sounds hit the bottom of the lake or sea and bounce back. The display unit measures the time delay as the signal goes out and returns. [. . . ] You must also select the area or "window" of the water you want to zoom. Zoom area When you turn on the zoom feature, it can only enlarge a part of the FishFinder Page. You must decide which part you want to enlarge. As we said, the right side of the "split" display shows the normal FishFinder Page. The vertical line at the right edge of this display shows the area or "window" of the water being enlarged. When the FishFinder is set for Auto Zoom, it will choose the zoom area automatically. The unit always chooses an area of the water which includes the bottom. The unit then moves this area up or down to keep the bottom in the picture. The Auto Zoom feature is great for bottom fishing. You may also set the zoom area manually. While the Zoom screen is visible, press SETUP . This will bring you to the Zoom Menu, shown in Fig. Once you are back to the zoom display, you can move the zoom area up or down (using the and arrows of the Page Control Pad) to select the area you want to be enlarged. The Zoom image can also be presented using the whole display. If you want to exit from the Zoom Mode, press the Zoom button again while the Zoom image is visible. For a moment the display will say, "Exiting Zoom Mode, " then the unit will return to the FishFinder Page. 50 Operating Instructions A-Scope (Bottom Coverage) Mode Normal display A-Scope display A-Scope image (real time image) Fig. 3-14 A-Scope Mode (half screen) Fish indication Bottom coverage On the FishFinder Page the bottom graph is "drawn" after the FishFinder receives several echoes. This has the effect of showing a record of the bottom contour. The A-scope Mode shows raw sonar data directly from the transducer beam. This gives you a "real time" image of fish and bottom structure directly below the transducer. (The A-Scope Mode is sometimes called an "In-Line Flasher. ") This function is very useful in showing the strength of the echo returned from a fish. You can reach the A-Scope Mode at any time by pressing the A-Scope button. [. . . ] Sometimes a thermocline can reflect sonar waves and present a false display. Transducer: A device which sends and receives high frequency sound waves through the water. Transom: The rear-most part of the boat's hull, often a flat panel. White Line: A feature used to help display fish near the bottom. [. . . ]