Navigation and Seamanship

3.1.8.7. Controls of typical echosounder

An echo sounder will normally have the following controls:

Range Switch – to select the range between which the depth is be checked e.g. 0- 50 m, 1 – 100 m, 100 – 200 m etc. Always check the lowest range first before shifting to a higher range.

Unit selector switch – to select the unit feet, fathoms or meter as required.

Gain switch – Zero Adjustment or Draught setting control – the echo sounder will normally display the depth below the keel. This switch can be used to feed the ship’s draught such that the echo sounder will display the total sea depth. This switch is also used to adjust the start of the transmission of the sound pulse to be in line with the zero of the scale in use.

Fix or event marker - this button is used to mark to indicate certain time e.g. passing a navigational mark, when a position is plotted on the chart etc.

Transducer changeover switch – in case vessel has more than one switch e.g. forward and aft transducer.

Dimmer – to illuminate the display as required.

SONAR and net sonde are other equipments working with the same principle, much useful for the fishermen in aimed fishing. The details of these two equipments could be explained in the later part of this course.