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You can calculate the maximum theoretical target detection range using the following
formula:
D = 2.23 (√h1 + √h2)
where:
•
D is distance traveled by the radar beam
•
h1 is the height above sea level of the scanner
•
h2 is the height above sea level of a target
An example is shown below:
In this example, the scanner is installed on the vessel at a height of 3 m (10 ft) above sea level
(h1). Island A is 10 m (33 ft) high (h2) and for comparison, island B is 5 m (16.4 ft) high (h2).
Both islands are at a distance (D) of 10 nautical miles from the vessel.
Calculations using the formula show that, at this distance, the radar can only detect objects
that are more than 7.6 m (25 ft) high, which means that island A is shown on the radar but
island B is not shown.
Remember that:
•
The maximum detection range of the radar is limited by the curvature of the earth's surface
under normal conditions of wave propagation.
•
Bad weather conditions can reduce the maximum detection range.
Reduce false echoes and shadow zones
False echoes can be produced on the radar display if the scanner is installed too close to an
object on the vessel's superstructure. This object can block the radar beam and refl ect it back,
generating false echoes and shadow zones.
If you are having problems with false echoes and/or shadow zones, re-install the scanner at a
higher location where the radar beam will be clear of any obstructions.
If this is not possible, try relocating the scanner away from the central keel line of the vessel to
the starboard side. This will move any shadows to the port side, maximize the radar view of
your give way sector, and ensure a clear view of the area around the vessel at the bow.
Use the following formula to calculate the distance that you'll need to move the scanner:
Ls = 0.4R + D/2 (when R is less than 49 ft [15 m])
Ls = 0.025R + D/2 (When R is greater than or equal to 49 ft [15 m])
where:
Ls = distance to be moved from the keel line
Pre installation checks |
D
10kW and 25kW Installation Manual
| 7
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