Buying Tips from the Marine Electronics Journal
How to Buy Marine Electronics
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.
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
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
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
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.
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
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