Grade 12 – Nautical Science

September 20, 2020

Echo sounder

An echo sounder is the instrument used to determine the depth of water beneath the keel. In order to do this it transmits pulses of sound which bounce off the sea bed. How does it work? The echo sounder system comprises four components, namely a transmitter, a receiver, a transducer […]
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September 20, 2020

Radar

Radar has already been covered in a module devoted entirely to it (see menu item 1.3), so it will not be discussed further here.
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September 20, 2020

Automatic radar plotting aid (ARPA)

As mentioned previously, most radars today are equipped with ARPA. ARPA performs many of the functions covered in the radar module automatically and continuously. This saves the officer of the watch from having to do so manually and enables him to focus on his other duties. What are the capabilities […]
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September 20, 2020

Automatic identification system (AIS)

In the past a ship’s identity and details had to be obtained by establishing communications with it either by flashing light or radio. As can be imagined this was time consuming and in a heavy traffic area a bit hazardous. This has now been replaced by an automated system referred […]
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September 20, 2020

Global positioning system

The global positioning system utilises a constellation of 31 satellites orbiting the earth at very high altitudes. It was developed in 1973 and became operational in 1994. Initially only 24 satellites were used but in 2000 it was decided to upgrade the system to GPSIII. The system is owned by […]
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