JRC JMA-2343, Instruction Manual

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(2) Precautions to be observed when installing the scanner unit on a yacht
A yacht heels on the lee side when a wind with a certain level of force blows.
The following condition occurs if the heel angle exceeds 1/2 of the beam width:
•
On the windward side, the water surface lies outside the beam, weakening the
radio wave that is incident to the target on the water surface. Consequently,
the echo generated by this target is will hardly be visible on the radar screen.
Conversely, on the lee side:
•
Since the radio wave that is incident to the water surface is stronger, strong sea
clutter will develop. For yachts on which the heel is 1/2 or greater than the ver-
tical beam width (
θ ) , it is recommended that the scanner unit be installed on a
mounting base so that the scanner unit can be tilted on the left and right sides
according to the heel angle.
Beam width θ
Heel angle
Φ
Radar scanner unit
Horizontal line
Wind