Adjusting The A/C Sea Control.2-7 - Furuno 1751 Operator's Manual

Basic Operation
2. OPERATiONAL OVERVIEW
Adjusting the A/C SEA controt
Echoes from waves can be troublesome, covering the central part of the display with random
signals known as "sea dutter." The higher the waves, and the higher the scanner above the
water, the further the dutter will extend. Sea dutter appears on the screen as many small
echoes which might affect radar performance (see Figure 2-6 (A)). The
A/C SEA
control
reduces the amplification of echoes at short ranges (where dutter is the greatest) and to
progressively increase amplification as the range increases, so amplification will be normal
at those ranges where there is no sea dutter. The control is effective up to about 4 miles.
The proper setting of the A/C SEA should be such that the dutter is broken up into smal!
dots, and small targets become distinguishable.
If the control is not sufficiently advanced, other targets will be hidden in the dutter, while if
it is set too high, sea dutter and targets will both disappear from the screen. In most cases
turn the control clockwise until dutter has disappeared to leeward, but a little is still visible
windward. Figure 2-6 illustrates how to adjust the control.
(A) Sea dutter, A/C SEA OFF (B) A/C SEA properly adjusted
Figure 2-6 Adjusting the A/C SEA Control
Tips on adjusting A/C SEA
1) A common mistake is to over-adjust the control so all the dutter Ls removed. By rotating the
control fully clockwise, you will see how the center of the screen heconies dark. This dark zone
can be dangerous (targets may be missed), especially if the gain is not properly adjusted.
Always leave a little dutter visible on the screen to be sure weak echoes will not be suppressed.
ff there is no dutter, leave the control in the fully counterdockwise position.
2) The GAIN is normally set to the point where there is a trace of noise speckles showing on
the screen on a long range, and then adjust the
A/C SEA
control on a short range so you
can see close-in targets in a harbor situation clearly. This equalizes the GAIN and A/C
SEA characteristics for all ranges.
3) In moderate conditions on the open sea, where there are no definite targets on the shorter
ranges, you should still adjust the GAIN on a long range for some noise speckles on the
display, and then go down to a short range to adjust the A/C SEA until you can see a bit
of sea dutter close to the boat.
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