What is Radar?
Marine radar is a navigation and collision-avoidance system made up of a rotating antenna (either a dome or open array) mounted high on the boat, a display unit at the helm, and connecting cables.
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What it is
Marine radar is a navigation and collision-avoidance system made up of a rotating antenna (either a dome or open array) mounted high on the boat, a display unit at the helm, and connecting cables. The antenna transmits short pulses of microwave energy and receives the echoes reflected from nearby objects such as land, boats, buoys, and weather formations. Modern radars include both traditional pulse systems and Doppler or solid-state radars, which provide better target tracking, lower power use and the ability to distinguish moving targets.
What it does
Marine radar sends out short bursts of microwave energy that travel at the speed of light, bounce off objects, and return as echoes. The radar measures how long it takes for the echoes to return to calculate distance, and it uses the antenna’s rotation angle to determine direction. The display shows a 360-degree view of your surroundings. Most modern units can track targets, issue collision alerts, and show which objects are moving versus stationary.
Why it matters
Radar is your primary collision avoidance tool in fog, darkness, heavy rain or rough seas when visual lookout is compromised. It can detect vessels miles away long before they're visible, giving you time to maneuver safely. Radar can also identify squalls and thunderstorms.
General Maintenance
Radar domes are expensive and can be damaged by impact, UV exposure, or water intrusion. Inspect the dome regularly for cracks, discoloration, or physical damage (especially after storms or when rafting alongside other boats). Make sure the antenna rotates smoothly and the mounting bracket is tight with no corrosion or looseness. Test the radar regularly by comparing known targets such as buoys or landmarks to what appears on the display, confirming clear targets and accurate range. Clean the dome exterior every few months with fresh water and mild soap. Check cable connections annually for corrosion or moisture, particularly at the dome end where water intrusion is most common. Most manufacturers recommend a professional inspection and test once per year. Even if the radar appears functional, replacement of the dome or array may be recommended every 10–15 years due to gradual UV and weather degradation.
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