Navman 4433, 4432 Frequency and cone width, Shadows, Example of shadows, Depth 83 kHz 200 kHz

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Frequency and cone width

The pulse generated by the FISH 4432/4433 transducer travels down through the water, spreading outwards to form a rough cone shape. However, the cone width is dependent upon the frequency of the pulse; at 83 kHz it is 20°, whereas at 200 kHz it is 14°. The chart shows how the cone width varies over depth for each frequency used. Figures are approximate.

Depth

83 kHz

200 kHz

0

20°

14°

 

50

18

12

 

100

30

25

 

 

150

55

37

 

 

200

73

50

 

 

250

91

62

 

 

Water

Cone width

Cone width

Depth

at 83 kHz

at 200 kHz

 

 

 

10

4

2

20

7

5

30

11

7

40

15

10

50

18

12

60

22

15

70

25

17

80

29

20

90

33

22

100

36

25

150

55

37

200

73

50

300

109

75

400

146

100

500

182

125

600

218

149

700

255

174

800

291

199

900

328

224

1000

364

249

 

 

 

The differences in the cone width affect what is displayed. See section 4-2 Single and Dual Frequency fishfinding.

Shadows

Shadows are created around areas where the ultrasonic beam cannot ‘see’. These areas include hollows on the bottom or beside rocks and ledges, where the strong echoes returned off the rocks obscure the weak echoes of the fish and may also create a double bottom trace. See following for an example of the sonar display in such an environment. A double bottom trace is shown on the display.

When looking for fish with the wide angled 83 kHz frequency, be aware of increased shadows. Use the high frequency 200 kHz in areas that have rocks and ledges because this frequency reduces the shadow effect considerably.

Example of shadows

Sonar display of same area

Fish is visible on the display

Fish is hidden by the strong echoes off the bottom and is not shown on the display

Fish is visible on the display

FISH 4432/4433 Installation and Operation Manual

NAVMAN

18

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Contents Pilot Contents Navman Introduction Benefits of the Fish 4432/4433How the Fish 4432/4433 works Basic OperationKey Names Power On / Auto Power Power OffBacklight Adjustment Key OperationSimulate Mode Setting up the Fish 4432/4433Manual, Fishing and Cruising Modes Setup menu and options Setup System Auto power offBacklight Snooze Mode Factory resetFish symbols Pulse powerScroll speed Digit sizeSetup Logs Reset trip distReset total dist Reset engine hoursSetup Alarms Alarms automatically re-enableSetup Units Flashing light and/or external beeperSetup Comms 4433 only Setup CalibrateNmea data Nmea OutTemperature Temp filterFuel Keel offsetUsing the Fish 4432/4433 Interpreting the displayStrength of echoes Bottom typesFrequency and cone width ShadowsExample of shadows Depth 83 kHz 200 kHzWhen to use 83 kHz Single and Dual frequency fishfinding When to use 200 kHzAuto frequency KHz display 200/83 Khz displayFish symbols On Fish detection and display Where to find fishFish arches Changing between Cruising, Fishing and Manual GainObtaining the best results Range Changing the Range ModeZoom Range and Zoom Offset Displays Display menuSonar display Data headerSonar History Sonar Zoom displayScope Bottom lockSonar 83/200 display Sonar Bottom displaySonar A-Scope display Scope perspective view Fish recognitionFuel display 4433 only Data display About displayWiring Options Basic wiringNmea wiring Option Fish 4433 only Wire FunctionSecondary alarm wiring option Fish 4433 only Fuel kit wiring Fish 4433 onlyAuto power option Through hull transducersWhat comes with this product? Options and AccessoriesMounting and removing the display unit Flush Mounting Removing the display unitBracket Mounting Systems of several instruments 4433 0nlyCleaning and maintenance RepeatAppendix a Specifications Specifications FishAppendix B Dimensions Appendix C Troubleshooting Fishfinder won’t turn onFishfinder won’t turn off Fishfinder operates erraticallyBottom is not displayed Bottom is displayed too far up the screenTwin engine installation shows only one flow rate Flow indicates no fuel or low fuelErratic Fuel Flow readings There is no reading for fuel economyHow to contact us OceaniaFish 4 432 / 4