This section covers the features and operation of the GMR 21/41.
Understanding Radar
The GMR 21/41 transmits a narrow beam of microwave energy in a rotating 360° pattern. When the transmitted energy contacts a target, some of that energy is reflected and returned to the scanner. The scanner collects the returned energy for processing and display. Your GMR 21/41 is operated and adjusted using controls on your Garmin Marine Network chartplotter. You can view radar data on the Radar Page or as an overlay on the Map Page. All radar controls are accessible from both pages.
When you turn on the radar, the status bar shows the message “Radar Warming Up” with a countdown to Standby Mode. The countdown also appears in the middle of the Radar Page. When the countdown reaches 0 (zero), the “Hold FCTN to transmit” message appears.
As a safety feature, the radar enters Standby Mode after it warms up. This gives the operator an opportunity to verify that the area around the scanner is clear before beginning radar transmission. It is important to remember that the microwave energy transmitted by the scanner can potentially be dangerous.
Basic Operation > Understanding Radar
Caution: The GMR 21/41 transmits microwave energy that has the potential to be harmful to humans and animals. Before beginning radar transmission, verify that the area around the radar is clear. The radar transmits a beam approximately 12° above and below a line extending horizontally from the center of the scanner. Avoid looking directly at the scanner, because the eyes are the most susceptible part of the body.
When the area surrounding the scanner is clear, press and hold FCTN. The message “Do you want to begin radar transmission?” is shown. Select Yes, and then press ENTER.
GMR 21/41 Owner’s Manual | 1 |