Garmin GPSMAP 495 User Manual

Page 137

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GPSMAP 495 Owner’s Manual

129

Setting up and Using Sonar >

Understanding Sonar

Transducer Coverage

The area covered by the transmitted sound waves is determined by

the cone angle of the transducer and the water depth. The wide cone

angles (40°), associated with low frequencies (50 kHz) provide a

large coverage area for finding fish within a coverage width that

is approximately 2/3 of the water depth. However, this also means

that wide cone angles produce less bottom detail and resolution. As

shown in the drawing on the near right, the 40° cone angle produces

a coverage area of approximately a 20-foot diameter circle at a

30-foot depth.
The narrow cone angles (10°) associated with the high frequencies

(200 kHz) provide better bottom resolution and crisper detail, but

cannot show a large coverage area for finding fish. The 10° cone

angle provides a coverage width that is approximately 1/5 of the

water depth. As shown in the drawing on the far right, the 10° cone

angle produces a coverage area of approximately a 6-foot diameter

circle at a 30-foot depth.
Dual frequency mode combines both frequencies to get the best

coverage area and contour/depth readings.

40° Cone Angle (50 kHz)

Coverage

Diameter

Depth

10° Cone Angle (200 kHz)

Coverage

Diameter

Depth

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