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Buying Tips from the Marine Electronics Journal

How to Buy Marine Electronics

Radar mainly functions as an anticollision aid, but it also provides information on the location of neighboring vessels, the outline of the coast, weather and other objects that may intercept your intended course. One of the benefits of having a radar on board is the ability to navigate in fog or darkness, where the visibility is poor or zero. With radar acting as your eyes, you have the ability to monitor your vessel and other vessels’ movements around you.

Collision avoidance
Radars incorporate many alarms to keep you aware of what is happening in your vicinity. One of those alarms is the guard alarm, which alerts you when targets enter a particular predefined area or if your own vessel is nearing a danger area. The alarm area can be an area forward of your vessel or a 360 degree circle around it. When radar targets such as other vessels, land masses and buoys enter the zone, an audible alarm sounds.

Assess target movement
If the radar has an echo trail feature, it will simulate target movement with an afterglow. This is useful for assessing the movement of all targets relative to your own vessel. Some radars have the capability to show the true movement of targets, providing increased navigational safety.

Determine your vessel’s position
Since radar sees further than the naked eye, the echoes from islands and land masses can be used to determine your vessel’s position. When running near land, you can use peninsulas and other targets whose echoes show distinct contours on the display to determine your vessel’s position.

Navigate to specific locations
Fishing vessels and pleasure boats use radar to help them navigate to favorite fishing spots. When sailing to a fishing spot, the forces of wind and current combine to throw the vessel off its intended course. To remember your location if your ship drifts, use the Variable Range Marker (VRM) and the Electronic Bearing Line (EBL) to mark range and bearing to nearby islands or peninsulas. Many new radars can now overlay their targets on top of an electronic chart, making navigation to specific locations even easier.

Avoiding potential pitfalls with your radar
One thing to always keep in mind is that operating a radar is kind of like operating a computer: It takes time and experience to properly utilize the unit and all of its features. Many times people think that there is something wrong with their radar, when it is actually a setting that has been changed that is causing the problem. Other times, a physical change during the installation may affect the radar’s performance. Here is a list of some typical pitfalls to avoid when installing and operating your new radar:

Dome antenna snafus
The antenna is one of the main components of a radar system and should be treated with care during installation and use. Dome antennas are waterproof, but you must be careful not to drill holes in it to mount other items such as lights on top of it. Drilling holes into the dome will interfere with the integrity of the construction and will cause splitting and water leakage, damaging the inner workings. Also, painting an antenna is not recommended. If you must paint the antenna, do not use a lead or metallic-based paint.

Eliminate antenna interference
A radar is a line of sight product, meaning that it can only display the echoes it can see. When scouting for a place to mount your antenna, you should find a location that is the highest point on the vessel with an unobstructed view. Avoid mounting it where a portion of the 360-degree scanning beam is blocked by the vessel’s superstructure or rigging. Also, do not cluster other antennas such as your VHF and GPS antennas around the radar antenna. Clustering the antennas may cause interference with your radar or other products.

Range discrepancies
When you purchase your radar, one of the specifications you will be comparing is the range or distance that the radar can see. Many people will say that their radar can only see 12 miles when it claims it has a maximum range of 48 miles. As stated above, a radar is a line of sight product and the primary limiting factor in maximum range is the horizon. Radar waves do not bend around the earth’s curvature. The height of the antenna and of the target are the critical elements in determining the maximum range at which a target can be acquired by your radar.

When more gain is actually less
The gain control adjusts the radar receiver’s sensitivity, which incites most people’s tendency to increase the gain or sensitivity for a clearer picture. Too much gain is usually the culprit when the radar screen is filled with noise and you can not see anything. Here is the rule of thumb with gain:

To get the best maximum range, use a longer range scale, set the gain higher and turn the STC (Sensitivity Time Control) off.

To get the best minimum range, use a shorter range scale, set the gain lower and use STC with caution. Usually if you use only enough gain to add some speckles to the background and then back it off, you will get the results you desire.

Practice makes perfect
Like the old saying, “practice makes perfect,” the best time to learn how to use your radar is when you don’t need it! Turn your radar on when it is sunny out and visibility is good. Pick out targets that you can visually see, such as land, buoys and boats. Now track them on your radar to see how they look on the screen. Once you master the art of tracking targets during nice weather, you will be ready to use your radar to navigate safely when you need it.

Author: ME

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