Marine Radar

A marine radar (Radio Detection and Ranging) is an active electronic navigation system used to detect surface vessels, landmasses, and weather fronts regardless of visibility. Unlike passive receivers or collision-avoidance equipment linked to how GPS works, radar emits its own electromagnetic pulses and measures the echo delay and angle of arrival to calculate target distance and bearing.

On recreational sailing craft, compact radome antennas operating in the X-band (9.3–9.5 GHz, ~3 cm wavelength) are standard. According to Wikipedia, a sailing mast is a vertical spar designed to carry sails as well as elevated navigational equipment such as radar scanners. The scanner's height above the waterline directly governs the radar horizon; an antenna mounted at 4 meters (13.1 ft) provides a theoretical radar horizon of approximately 4.4 nautical miles (NM) for a surface-level target.

Horizontal beamwidth for standard yacht radomes ranges from 3.5° to 6°, defining the radar's bearing resolution. Skippers must distinguish active radar from passive radar reflectors and AIS broadcasts, which only report cooperative targets. Safe operation requires manual fine-tuning of gain control alongside sea clutter and rain clutter suppression filters to avoid losing small fiberglass or wooden hulls on the display, while keeping heading alignment tied to a marine compass.