Navaleye
You could perhaps see tracks out to 250nm if the aircraft was flying at 40,000'. If it descended to 10,000 then, assuming your antenna was 60' above the waterline, your horizon would be somewhere in the region of 132nm. If it descended to 5,000 the it would reduce to about 96nm - on a good day with a following wind. (Calibrated Range for Type 1022 was 225nm.