Furuno MFD8 Guía Del Usuario

7.  Fish Finder

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.

•  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