ECDIS is an integrated electronic navigation system which combines the data obtained from a number of electronic navigation sensors and displays it on a video display unit/monitor both in the form of a graphic image and alpha-numeric information. The sensors providing the data inputs to ECDIS are the following: The global positioning system (GPS and/or…
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 the United States of America…
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 This has now been replaced by an automated system referred to as AIS. Since December…
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 of ARPA? Capabilities: It can…
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 and a display unit. The…
The ship’s log is basically the “speedometer and odometer” of a vessel. And performs exactly the same function as that of a motor car, i.e. it records the speed of the vessel and the distance travelled. Initially logs were purely mechanical and required no electrical power to operate. They only recorded the distance covered by…
Except for small recreational vessels, most vessels are equipped with two types of compass, namely a gyro and a magnetic compass. The former is used as the primary compass with the latter as back-up in the event of gyro or power failure. Since the latter makes use of the earth’s magnetic field and is not…
Introduction. On modern sea-going vessels there are a number of electronic navigation systems and equipment which are designed to assist the navigator to navigate his vessel safely. They are: The gyro compass. Ship’s log. Echo sounder (depth recorder). Radar. Automatic radar plotting assistant (ARPA). Automatic identification system (AIS). Global positioning system (GPS). Electronic chart display…
Why do we need to do radar plotting? The International Regulations for the Prevention of Collisions at Sea (1972) as amended (Colregs) requires the systematic observations of targets. Extracts from Rule 7 b. and c. state: Rule 7b. “Proper use shall be made of radar equipment if fitted and operational, including long range scanning to…
