Points Officer on Watch (OOW) while handling ship’s radar
The officer on watch (OOW) on the ship’s bridge should be familiar with the working of all navigational equipment used on the ship. He should also be aware of the procedure for trouble shooting in case any equipment fails.
The radar is one of the most important navigational tools used on the ship. It should be kept running all the time and must undergo periodic tests to check presence of any operational error.
However, there are certain points that the officer on watch (OOW) should be aware of while operating the marine radar. This would not only ensure smooth running of the radar but also prevent sacrificing ship’s safety.
Points to note while handling ship’s radar :
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The officer on watch should keep a close watch on the ship’s course as sometimes small vessels, objects, and ice may not be detected.
- Shadow and blind sectors should also be taken care of while navigating by ship’s radar.
- Plotting of targets should be done at longer range.
- The officer must use multiple plotting to increase accuracy.
- Detection of small targets is better at short range.
- The officer on watch should know how to handle video processing techniques.
- Long range should be used to get advance notice of approaching vessels, ports, and obstacles.
- While deciding the range scale two things should be kept in mind –ship traffic in the region and ship’s speed.
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Radar operation should be efficiently practiced in clear weather. This helps the operator to get a better idea about radar observations and target vectors during restricted visibility.
- The officer on watch should also consider re-plotting or re-checking when there is a change in ship’s speed or course.
- The officer should keep a watch on the variable range market, fixed range lines and electronic bearing lines.
- Safe speed of the ship should be decided after using long range to detect approaching vessels and land.
- The operating officer must know how to use clutter control to avoid unclear objects
- Heading marker should be properly aligned with the fore and aft of the ship and also with the compass heading.
- The parallel index lines should be set correctly.
- The officer on watch must check for any gyro error and accuracy of the heading line arrangement.
- If a performance monitor is fitted, the quality of the performance must be checked at regular intervals of time.
- The officer must check the identity of the fixed object under consideration.
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While deciding the closest point of approach (CPA) to avoid collision of the ship, factors such as course, speed, and aspect of the target should be taken into account. Other important aspects of the ship should also be considered to mark the CPA correctly.
This is not an exhaustive list, but the above mentioned points should be considered without fail while handling a ship’s radar. Do you know any other important points that should be taken into consideration?
How Does Marine Radar Works
The term “Radar” is an acronym for Radio Detection and Ranging”. The marine radar works on the basic principle of electromagnetic waves. The radar antenna sends the high-speed electromagnetic waves to establish the location, which is the distance, the velocity and the direction the wave travelled along with the altitude of the object, moving or stationary.
Electromagnetic energy travels through air at a high constant speed, equivalent to the speed of light (300,000 kilometres per second).
The object may vary from ships, boats, terrain, weather formation, cost etc.
Let us understand how does the marine radar works :
The radar system out electromagnetic waves as a high-speed, signal which will travel several miles in the direction of radar facing. If there are no objects in the direction of the wave, the radar screen will show blank.
If there is an object, which will reflect the wave back to the radar, the computer set up of the radar will determine the distance between the ship and the object along with its location. Hence, it can be said that the radar basically reads two things – The position of the object and the direction of the same.
Position of the object: The radar antenna is continuously rotating on top of the ship sending and receiving signals. Hence, the radar is sweeping the signals all around the ship. As the radar pulse waves are reflected by an object, it will travel in the same direction and will be received by the radar detecting the position of the object. When the pulses are received back, the computer screen will log the position.
Distance from the ship: As the radar antenna is constantly sending and receiving signals from the object on the way of the electromagnetic signal, the received signal is sent back to the computer unit, which calculates the time taken for the signal to reflect back to the radar. Once the computer knows the time, it will calculate the distance by using the speed and time formula.
Marine Radar Diagram
The basic components of marine radar are shown in the below diagram :
Uses of Marine Radar
- To calculate range and bearing of a target and thereafter use the information to determine speed, course etc.
- Integration with other shipboard equipment (such as ECDIS) to derive precise data.
- Navigating own vessel and her course with regard to collision avoidance.
- Fixing the ship’s position using terrestrial objects such as lighthouses, buoys etc.
- Differentiating between targets in high traffic density areas.
- Determination of the weather, to an extent.
- Use by VTS in controlling coastal traffic.
- Usage of features such as parallel indexing to ensure safe navigation.
- Alleviating workload on the OOW on the bridge.
- Used extensively in pilotage that covers the above aspects.
The marine radar is a much bigger subject than is laid out in the article which only skims the surface of the operation and the uses of the radar. As an OOW, it is important to be thorough with the radar and study its operation and features extensively along with the limitations of the radar. A good book to start with is Shipborne Radar and ARPA by Capt. H. Subramaniam.
The most important point about marine radars is that the screens used to view the position of the objects are either LED screens or monochrome screens. With such perfect screens, the clarity of the objects is highlighted even further. Also since these screens are waterproof there is no threat of interruption to the ship radar system in times of rough weather.
The tracking ship system has further been developed to include even boats. This means that even boat owners can be assured of their vessel’s safety while on the water.
One major advantage of marine radars is that the power and electricity consumption by them is far too less. This means that the marine radars are not just user-friendly but also help the shipowner to regulate the cost of power and electricity.
Radar has been a major instrument to help marine navigation since the past six decades. Over the years, radar technology has developed to include not just aircraft but ships as well.
Marine travel and safety thus have become very feasible. It can be hoped, that in the future more such tracking devices will be developed so that several marine accidents and casualties can be prevented.
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