September 10, 2020

Possible shortcomings

Radar is referred to as an aid to navigation because it has certain shortcomings that could result in a collision or grounding if it is relied on exclusively. These shortcomings are: Size of target. Radio waves reflect very well from large objects but sometimes small objects are missed because of […]
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September 17, 2020

Coastal navigation techniques

How do we utilise radar for normal navigation purposes under normal conditions of visibility? There are four basic ways: Fix by radar range and visual bearing. This is used when there are few recognisable navigation marks ashore for visual bearings. Fix using radar ranges as position arcs. This is the […]
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September 17, 2020

Blind pilotage techniques

Radar really comes into its own during poor visibility. The techniques that will be described in this section applies to such circumstances. Whilst most modern marine radars now have a computer built in (ARPA – Automatic Radar Plotting Aid), which provides many more features than the older sets, the basic […]
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September 17, 2020

Radar plotting

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, […]
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September 20, 2020

Electronic navigation systems

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 […]
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