August 11, 2011:
Britain retired the last of their Nimrod maritime reconnaissance aircraft two years ago, and have since adapted their E-3D AWACS (air warning and control systems) radar aircraft to take up some of the slack. Britain modified the E-3 radar to also detect large ships at distances of up to 380 kilometers. Large aircraft can still be detected out to 500 kilometers. Smaller aircraft or ships need to be closer to be detected. In this respect, radar isn’t much different than eyesight.
The Searchwater radar on the older Nimrod has about half the range of the E-3D radar, but can see in much greater detail. But given the lack of any replacement for the Nimrod, the E-3D's ability to scan the ocean surface is better than nothing.