11
3.3.3 Shifting away from obstacles
symbol 129 \f "Wingdings" \s 10
Shifting from keel line
By shifting the scanner position from the keel line to the starboard side of the ship, it is
possible to move shadow zones to the port side which makes it possible to keep clear vision in the
bow direction. The distance to be shifted can be obtained by calculation depending on the distance
from the scanner to obstacles using the following equation:
Ls=0.4R+D/2 [m]
(when R<15m)
Ls=0.025R+D/2 [m]
(when R>=15m)
where
Ls = distance to be shifted from keel line
D = diameter of obstacle on keel line
R = distance from scanner to obstacle
symbol 130 \f "Wingdings" \s 10
Obtaining sufficient dip angle
Raise the scanner position so that there is a sufficient dip angle symbol 113 \f "Symbol" \s 10
θ
available between the line of sight from the scanner to the obstacle and the horizontal line. By
raising the dip angle above 5symbol 176 \f "Symbol" \s 10
°
, it is possible to prevent mid- and long-
distance shadow zones. The radar cannot detect objects below the line of sight.
Fig.3-1 Shifting from keel line
Fig.3-2 Obtaining sufficient dip angle
