7. Fish Finder
7-17
7.12 ACCU-FISH
The ACCU-FISH feature estimates the length of each fish and shows a fish symbol
and depth value or fish length. The information given by this feature is for only refer-
ence purposes.
ACCU-FISH uses the high- and low-frequency echoes that return at the center of the
transducer beam to calculate the length of a fish. The fish for the calculation of length
are taken from the high-frequency beam. The length of a fish is calculated from the
strength of the fish found with the low-frequency beam. In the example below, the fish
at the center of the illustration is used for the calculation.
How to use ACCU-FISH
• The intensity of an echo depends on fish species. If the indicated length is different
from the true length, you can apply an offset at the [Fish Finder-DFF/FCV] menu.
• 50 kHz and 200 kHz beams are transmitted alternately without reference to the cur-
rent display mode.
• To reduce the error, the detection area must be 2 to 100 meters from the surface.
• The signal attenuation on the inside-hull transducer is different between 50 kHz and
200 kHz. This attenuation causes some fish to get ignored and the fish length indi-
cated can be shorter than true length.
• Echoes from a school of fish can be in more than one layer, which can cause wrong
length indication.
• The fish symbol indication is not shown when the bottom echo does not appear on
the screen.
Low frequency
High frequency
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