Transducer Coverage - Garmin GPSMAP 495 Owner's Manual

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
Coverage
Depth
large coverage area for finding fish within a coverage width that
Diameter
is approximately 2/3 of the water depth. However, this also means
Depth
Coverage
that wide cone angles produce less bottom detail and resolution. As
Diameter
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
40° Cone Angle (50 kHz) 10° Cone Angle (200 kHz)
circle at a 30-foot depth.
Dual frequency mode combines both frequencies to get the best
coverage area and contour/depth readings.
GPSMAP 495 Owner's Manual 129