There are two stabilisation modes on Radar – ground and sea.
Ground stabilisation means that the display is referenced to the seabed by GNSS or through a twin-axis Doppler log.
For sea stabilisation the display is referenced to the sea current that own ship is experiencing, typically based on SDME measurements.
It is generally accepted that the ground stabilised mode is more useful for normal navigation, especially when combined with setting tracked targets to show their True vectors. However, since set and drift affect heading and aspect, ground stabilised displays should be used with caution where target tracking is concerned.
Sea stabilisation mode gives the navigator a better understanding about the aspect and therefore is used in collision avoidance.