Furuno 1830 - Page 25

Note that a shadow cannot be fairly estimated in heavy dutter, as echoes
from either side of the sector may be spread into it and give an illusion that
objeots in the sector ore being observed. Nor can it be satisfacturily
determined in confined waters, because of the probability of indirect. false
or multiple echoes being produced from nearby buildings or other vessels.
Fig.16 Appearance of a
Shadow Sector on
the Display Screen
The result of the above tneasurement ahould be rccordcd on a blind shadow
Sector diagram. Fig.lS is an example of a shadow sector diagram for the
Scanner Unit sited as in Fig.l7. The blind shadow sector diagram should be
fixed near the Display Unit.
Blind Sector
Fig.n Shadows caused by objects
0 «
180 “
Fig.18 Shadow Sector Diagram for
Scanner sited as in left
figure
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