Radar is most useful at night and in rain or fog. Even during the day in clear weather, radar improves visual acuity and depth perception by giving the precise bearing and range to a target. It also extends your visual horizon because the radar antenna is usually mounted well above the deck. Radar can detect and monitor storms and squalls high in the atmosphere long before they are visible to the eye.
The best way of learning to use a radar set is to read its manual and practice with it, especially in rain and fog when the automatic settings will not work well.
Gain adjusts for background noise that causes speckle on the screen. Increase it until speckle appears and then back off slightly. Long range detail is best viewed with slight speckling. The rain clutter setting tunes out returns from rain or heavy fog near the boat. The fast time constant (FTC) setting tunes out clutter from rain farther away from the boat. The sea clutter setting tunes out returns from wave tops in high seas or when wind blows spray off the waves. Increasing any of
these reduces clutter and also sensitivity. In fog, remember also sound the horn every two minutes, giving one long blast and, only if not motoring, following it with two short blasts.