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Delay
Commonly called water column removal. Generally, the fish is towed off the bottom 10 - 15% of the Range setting. If
we are looking for a small target, that would require a 25 m (80 ft) Range setting, we would tow the fish 3-4 m (12 ft) off
the bottom. This insures that the transducers are low enough to produce shadowing for targets off the bottom, and high
enough off the bottom to insure the beam makes it out to the distance selected by the Range setting.
If bottom conditions (trees, debris, etc) do not allow the fish to be towed 10 - 15% off the bottom, then a significant amount
of display space may be wasted just waiting for the acoustic wave to reach the bottom. If bottom conditions required
the fish to be towed 10 m off the bottom, and we are operating in the 25 m Range position (due to small target size); then
the first half of the printed line will be blank (light color). Target #1 is printed in the middle of the right channel and target
#2 which is 24 m away, is missed completely.
Fish
10 m
#1
The Delay selection delays the start of the sampling sequence. If the Delay was set to 5 m, then one-half of the 10
m blank space would be eliminated. If set to 10 m, then all blank space would be eliminated, and both targets #1 and
#2 would be printed. If a 15 m Delay was selected, we would lose target #1, but would pick-up part of #3 which is greater
than 25 m from the fish.
#1
24 m
Display - Right Channel
Print Head-Right Channel
#1
No Delay
Display - Right Channel
Print Head-Right Channel
10 m Delay
#2
#2
23
#3
Display - Right Channel
Print Head-Right Channel
#1
5 m Delay
Display - Right Channel
Print Head-Right Channel
#2
15 m Delay
#3
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