Introduction to Marine Radar
Marine Radar is undoubtedly one of the vital and essential electronic navigation equipment for any commercial ship. For the deck cadet, training officer, or aspirant navigation officer, marine radar isn’t simply about passing exams – it’s about gaining the skills that keep the ship, crew, cargo, and environment secure.
Marine Radar teaching at Crack Merchant Navy Coaching is a unique combination of theoretical, simulator training and exam guidance to make the best out of the students in real-life situations at sea. This article will provide you the essential information to know about the basics of the Marine Radar and how it is methodology based on your STCW training, oral examinations, and duties onboard.
WHAT IS MARINE RADAR?
It consists of a rotating antenna that transmits pulses of RF energy then “listens” for any echoes of those pulses which are reflected back from any object and indicates the echor location on a display.
What is the full form of RADAR?
R A D A R
Radio detection and ranging
Marine radar · Marine radars work on the principle of bouncing radio waves of a certain frequency off of objects (obstacles, land, other ships) and capturing the return echoes. This essentially enables the person monitoring the vessel to ‘see’ around the ship whether it is foggy, raining, the seas are rough or in the dark.
Modern commercial vessels now incorporate Marine Radar with ARPA radar (Automatic Radar Plotting Aid), marine navigation systems including ECDIS, AIS and GPS to offer a comprehensive storm and situational awareness.
Importance of Marine Radar in the Merchant Navy
Marine Radar For the Merchant Navy is a key instrument for:
Safe navigation and collision avoidance.
Tracking traffic in busy waters, TSS (Traffic Separation Scheme), and pilotage regions.
Land and coastlines are also picked up by the radar during coastal navigation and landfall.
Safe navigation in restricted visibility according to COLREGS ->
Assistance in decision making in rough sea & restricted waters.
The importance of marine radar and arpa Every marine officer should have proficiency in marine radar, arpa STCW regulations and IMO model courses give strong emphasis to the importance of marine radar and arpa.
Questions on radar plotting, radar errors and limitations and collision avoidance feature heavily in the oral and written examinations for deck cadets and officers.
To the extent possible, Crack Merchant Navy Coaching trains students to think of such technical concepts in terms of the actual practice of watching a real bridge so you are ready for the exams and for the ship.
Principle of Operation of Marine Radar
The basic principle of Marine Radar is simple but powerful:
The radar sends a brief pulse of radio waves at high frequency (via an antenna).
These radiations move at the speed of light through the air.
When incident waves encounter an object (ship, land, buoy, rain), a portion of the energy is backscattered as an echo.
The radar receiver detects this echo.
On the basis of the time duration for this echo to come back, the distance of target is measured by the radar.
Using the known direction in which the antenna is pointing to at that time, the radar computes the target’s bearing.
Hence, at a given instant, the range and bearing of all targets may be plotted on the radar, giving rise to the well-known picture of echoes surrounding the ship.
In ARPA radar, the system takes all the targets that have been continuously tracked and uses relative motion calculations to predict Closest Point of Approach (CPA) and Time to CPA (TCPA), which are paramount in collision avoidance decisions.
Components of Marine Radar :
Synthetic Marine Radar (3D B-Scan) Visible minority of the brightest range cells from the along-range distributions can be plotted in a B-Scan 3D plot against image.
Antenna (scanner): Rotating antenna assembling at a certain height on the mast or the radar mast. Being sent and received radio pulses.
Transmitter: Produces high-energy RF pulses. Receiver: Senses and magnifies faint reflections bouncing back from targets.
Display Unit/Indicator: The radar targets on the screen (until recently a CRT, now an LCD) with which the officer interacts.
Processor/ARPA Unit: Performs signal processing to produce a stable image, track targets, and compute CPA/TCPA from echoes.
Range, gain, clutter controls, VRM/EBL, mode selection and various other operator’s controls.
But at Crack Merchant Navy, it is a complete package because not only the cadets are taught the names but also the purpose of each spare and common watches related checks while keeping a watch on the bridge.
Types Of Marine Radar :
There are two type Marine Radar
X-Band Radar (around 9 GHz)
Shorter wavelength higher frequency.
Higher resolution, can pick smaller targets – like small boats and buoys.
More susceptible to sea clutter and rain clutter
Commonly used for maritime navigation along coasts and for resolving targets.
S-Band Radar (around 3 GHz)
Longer wavelength Lower frequency
Superior rain, fog and sea clutter performance.
Can be found as the main radar in the close range and also for long history detection in the open sea as his lucky radar for good short range capability.
In exams as well as on board you will be frequently asked: “Which radar (x-band or s-band) would you choose in rain or heavy clutter and why?” The best solution is: “x is better for range though it suffers more in rain, so..”. Crack Merchant Navy Coaching covers such applied questions with lucid logic and practical shipboard examples.
Radar Display Modes and Range Scales
Understanding radar display modes is essential for both navigation and exam questions.
Common Display Modes
- Head-Up (HU): The ship’s heading is always at the top of the display. Bearings shown are relative. Good for immediate visual interpretation but picture rotates with heading changes.
- North-Up (NU): True north is fixed at the top, and the picture is stabilized. Useful for navigation and plotting on charts.
- Course-Up (CU): The ship’s course is kept at the top. Often used while following a steady course.
Range Scales
Marine Radar enable you to choose among various range scales based on your requirements e.g. 0.75 NM, 1.5 NM, 3 NM, 6 NM, 12 NM, 24 NM, … etc.
- Short ranges are used for pilotage, harbor approach, and close quarters maneuvering.
- Medium to long ranges are used for early detection of targets, coastal navigation, and traffic monitoring.
At Crack Merchant Navy, cadets practice selecting suitable modes and ranges for different scenarios: coastal passage, open sea, TSS crossing, and harbor entry.
Radar Plotting and Collision Avoidance
Radar plotting is an essential skill for all navigators. It is a basis for the collision avoidance using Marine Radar or ARPA.
General knowledge includes:
Relative motion true motion How own ship motion affects target motion on the display.
CPA (Closest Point of Approach): It is the shortest distance that will be passed between two ship, if they continue to follow their current heading and speed.
TCPA (time to CPA): Time remaining to CPA.
Vector displays True and relative vectors To analyze collision risk and assess the three time-dependent stages of the closest point of approach (CPA).
Manual radar plotting: the course, speed, CPA and TCPA of a target can be calculated manually using plotting sheets, range rings and bearings.
ARPA radar makes all of this automatic and tracks targets and shows you the CPA/TCPA directly. But STCW and the exams also expect you to know manual radar plotting, just in case of ARPA failure or limitations.
Crack Merchant Navy Coaching offers comprehensive guidance in radar plotting techniques, emphasizing on step by step training in Radar Plotting Techniques along with practice on several typical exam questions and shipboard scenarios.
Limitation Of Marine Radar :
Marine radar is very useful but not without shortcomings. A good officer is always alert to its limitations:
Blind sectors: Due to masts, funnels or any other object which obstructs the waves. Targets within the blind zones may be missed.
Shadowing An antenna placed near a high obstacle can be shadowed.
Range errors: Resulting from misadjustment, neglect or due to atmospheric conditions.
Errors in bearing: Antenna misalignment or gyro error.
Limitations in target discrimination: Very small or low-lying targets can be missed, particularly in heavy sea clutter.
ARPA tracking errors: Erroneous data entry (speed, course, gyro), lost target, unstable tracks.
STCW stipulates officers must be knowledgeable of these errors and not be blind followers of ship navigation radar;
At Crack Merchant Navy, these limitations are explained through incident real case studies so that students get the realizations of implications toward safety.
Marine Radar Training at Crack Merchant Navy
Crack Merchant Navy Coaching is also known for providing excellent coaching in Radar & ARPA Training with conceptual clarity and practical knowledge to the aspirants of marine.
Our Marine Radar Course content is concentrated on:
STCW Coverage: Includes all necessary theory along with principles and types, modes, errors and limitations.
Exam focused lectures: For written exams, orals, company interviews (which sometimes include questions on radar).
Radar plot practice: Manual and ARPA radar plot exercises, CPA/TCPA computations, and collision avoidance drills.
Simulator based learning: Ship navigation radar demonstrations, ARPA radar functions, clutter controls, and COLREG scenarios.
Real-life applicability: Why study passages in the classroom when you can go straight to the real bridge watchkeeping, passage planning, working procedures in restricted visibility, and emergency manoeuvring, among other things?
By the end of the module on Marine Radar in Crack Merchant Navy, every student is well versed not only in answering the exam questions, but confidently using radar while at sea.
Career Importance of Marine Radar Knowledge
In-depth knowledge of Marine Radar makes you more employable in the Merchant Navy:
For the deck cadets: It shows that you have knowledge of fundamental navigation equipment and you care about safety precautions.
Junior Officers (OOW): It is an important aspect of your capability as a bridge watch keeper, particularly in night and restricted visibility watches.
Senior (Chief Officer, Master): It is the foundation on which the subsequent stages of decision making, bridge team management and the prevention of the accident are based.
Candidates: Marine Radar and ARPA Shipping companies want sailors who can work the Marine Radar and ARPA confidently, who know how to read the information, and who are capable of making safe decisions.
When you have trained at an institute like Crack Merchant Navy where radar is taught keeping in mind both your exam and voyage you will definitely have an upper hand among others.
Read More : Merchant Seaman: Complete Guide by Crack Merchant Navy Coaching Centre
Conclusion
Marine Radar is far more than just an electronic screen displayed on the ship’s bridge – it is a life-critical, safety enhancement instrument that every Merchant Navy officer needs to know inside out. From the fundamental concepts and equipment to radar plotting, clutter management and COLREG application, the level of your knowledge in Marine Radar will have a direct effect on the degree that you can safely steer a ship.
For those aspiring to join, deck cadets and navigation officers in the Merchant Navy, who are on the lookout for a well structured, examination- ready as well as practically beneficial training, Crack Merchant Navy Coaching is your one stop destination for the Marine Radar course. With proper guidance, training and exposure to simulators, you can become proficient in Marine Radar and start your seafaring career on a winning note.
