Everything You Need to Know About Marine Radars


Introducing guest contributor Jim Maier

I'm Jim Maier, owner of BOE Marine. Working in the marine industry for the past 16 years, I have gained extensive knowledge of boat outfitting and marine electronics, which has inspired me to come up with sharing my knowledge through blogging and online platform from where recreational and commercial boaters can buy the latest, branded marine equipment on sale.

Marine Radar - Radio Detection and Ranging, is used to detect objects and their position relative to your current location. It works by sending out a radio signal. When the signal hits an object, it gets reflected back to the radar, which can then calculate a rough estimate of the object. It does so by detecting other ships and land obstacles, to give bearing and distance for collision avoidance and navigation while on water.

A marine radar device acts as a major navigation aid for boaters. It helps in detecting boats, birds, landmasses, and weather systems - even if the visibility is less than usual.

Marine radar: Top features to consider

The two fundamental features of a marine radar unit are transmitter power and beam angle. Power can range between 2-4 Kilowatts. Power is a crucial factor in defining how well your radar performs in bad weather. The higher the power of a radar, the better your transmitter can see through dense fog and rain, and the further the signal can reach. Blinding rain can lead to low power radar performing less than it should. Beam angle is determined by the size of a radar antenna. A long antenna emits a narrower beam that can discriminate better between objects that are close together than a shorter antenna. On the other hand, a short antenna produces a wider beam angle that lets radar scan a larger area than a long antenna at once. Antennas can be customized in most cases, and you can purchase them separately.

Guard zone alarm

The majority of marine radars let you set a guard zone around your vessel. You can specify the safety distance and set an alarm for danger. If your boat locates a buoy, a landmass or a similar hindrance within the region of your set guard zone, the alarm will sound.

Split-screen displays

The feature proves useful for, among other things, navigating through buoys as you leave the shore while heading out towards a distant spot. With the split screen displays, you can simultaneously control all the objects that are near your boat and the ones which are farther.

Using marine radar

One of the best features of marine radar is its ability to determine where you are in cohesion with where you were a couple of minutes ago. The "echo trail" feature is often used to determine how well you can navigate an obstacle separate from how well you can maintain the bearing you have set for your vessel. The echo trail is displayed on the radar's display screen so one can assess visually whatever is going on.

Integrated marine radar and GPS/chartplotters

Marine radars generally come at expensive price tag; many units run in the range of thousands of dollars. It is better to talk with boaters in your group or vicinity and see what they are using. Also, ask them what features they like before committing that much money. You can search for marine radars that come with other marine electronics, for example GPS units and chartplotters. Integrating the marine components lowers down the complications associated with your visual displays and cuts down the total cost of items. Although at times you may need to trade-off with the features offered within an integrated package, such radars provide complete value for boaters who sail as a hobby.

Tracking other boats using a marine radar system

Regardless of whether you are at sea on a chilling sailing holiday, involved in a commercial fishing adventure hundred miles offshore, or you are carrying freight from one port to another, keeping track of all objects on your way, like other boats and larger ships, comes in handy when you don’t want to compromise your safety on water for anything. With the latest generation of marine radar systems from Garmin, Raymarine, Simrad, you will be able to benefit from different technologies that make tracking other boats easier than before. Some radar domes and arrays even let you mark their positions and routes on the screen.

The ocean can be rude at times, and even a slight change in normal conditions can come on pretty much instantly. One minute you can be sailing across smooth water, the next minute, a dense fog can obscure the entire world around you, and you can be struggling with huge waves and high winds.

The always changing nature of water implies as conditions change, you can face different types of challenges that can impinge upon your safety too. The best way to ensure you remain safe is to remove as many factors that can change from the overall picture as you can. And for this, radars work the best!

Other boats are often a major threat any mariner can face. Sailors may miss the smaller boats on the same course while looking for bigger obstacles like large container ships and cruise liners. This minor negligence could make things fatal. It is the duty of the sailor and crew to keep an eye on the radar data as well as sea conditions around them in order to stay safe from everything including the small boats passing by.

Fortunately, even the fastest ships don’t move at more than about 25 knots at a time, implying if you have a radar that can cover 50 nautical miles, you have 30 minutes from the moment you first make contact with another boat till you meet. This would provide you with enough time to react and come up with a plan to adjust your navigation accordingly.

One of the best things about modern marine radar systems from brands like Furuno is they plot the relative position of other ships over time. So more than being abstract dots on the screen that provides little info, you can view other vessels as a track through the area. The movements are shown clearly, enabling you to gauge which vessels pose a threat to yours and take the right action.

When you’re on water and land is out of sight, your safety is your first priority. So instead of leaving your safety in the hands of other people, keep yourself prepped up and safe with a reliable marine radar system that works well. Get your boat a compatible open array radar or dome (depending on your needs) to make your course corrections on the basis of constantly updated data they provide.


Once you know how to read the information shared on your marine radar system, you can easily make well-informed decisions regarding navigation and abstain from any trouble at sea. When you know what’s approaching your vessel and what is happening beyond your sight, you can be confident you are safe. It gives you the ability to react timely to anything that happens around - whether a weather system, a wave, an oil tanker, or anything else.

It is important to know what other vessels are doing, but it is also important to keep tabs on what you are doing. By tracking your own course across the water, and making time to do it for other boats with a marine radar plotter, you can secure your boat, passengers, and crew even in the worst situations.

Header Image: Boat Steering Wheelhouse. Credit: Skitterphoto (Pixabay Licence)

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