Marine radar

Marine radars are X band or S band radars on ships, used to detect other ships and land hazards, to provide bearing and distance for collision avoidance and navigation at sea. They are electronic navigation instruments that use a rotating antenna to sweep a narrow beam of microwaves around the water surface surrounding the ship to the horizon, detecting targets by microwaves reflected from them, generating a picture of the ship's surroundings on a display. The X-Band and S-Band radar has different characteristics and detection capabilities compared with each other. Most merchant ships carry at least one of each type to ensure adequate target detection and response. For example, the S-band operates better in sea clutter and rain than the X-band, however, the X-band has greater definition and accuracy in clear weather.

Radar is a vital navigation component for safety at sea and near the shore. It allows a 'lookout' to be maintained, being one of the approved available means for compliance with Rule 5, keeping a proper lookout under the International Regulations for Preventing Collisions at Sea. Captains and the bridge teams of ships need to be able to maneuver their ships in close proximity to navigational hazards in the worst of conditions. These include a need to navigate "blind", when there is poor or no visibility at night or due to bad weather such as fog. In addition to vessel-based marine radars, in port or in harbour, shore-based vessel traffic service radar systems are used by harbormasters and coast guard to monitor and regulate ship movements in busy waters.