If you have ever been suddenly engulfed by fog, caught in a blinding rain storm, or disoriented by an array of confusing navigation lights against the backdrop of a light cluttered shoreline, then you will appreciate how radar's electronic vision will enhance your ability to navigate safely. For example, if you shout toward a cliff from a distance, after a six second delay you hear your own sound waves reflect back to you as an echo. The rotating scanner simultaneously determines the bearing from which the echo came. The results are then converted and displayed on the radar screen. Navigating with Radar Boaters assisted with radar can more confidently enlarge their cruising grounds without feeling completely at the mercy of the weather and darkness.
Most users operate radar in the heading-up mode because it's the easiest to interpret at a glance.
This means that the top of the display screen is always oriented with the bow of the boat, and targets on the screen are always relative to your own heading. A north-up mode is oriented so the top of the screen is always pointing north, making it possible to observe how navigation aids move on the screen as the boat remains on its intended track. Radars with a north-up mode must be interfaced with an electronic compass. Here the top of the screen is relative to the rhumb line course of a selected waypoint. This mode is also ideal for avoiding collisions.