You do calculations and dont have an accurate distance of the freighter, size of the island(map of the island for that matter) and current flow charts...sounds fresh to me 
I'll agree with you totally as far as a body floating on the wavy blue seas goes. Likely more complicated than an oceanographer telling Lenny on L&O where the body was dumped on the East River and when. The rocket, tho, isn't dependent upon currents, n-s-e-w headings, etc., but flies from pt A to pt B. Maybe. In a world without a protective electromagnetic bubble. The Economist seemed to provide enough data (speed, time) to calculate distance, I think somewhere around 40 miles if I recall correctly, from where the rocket nearly hit the chopper. But now the freighter is reportedly 85-90 miles offshore. Then again, it's been a couple/few/several days, and the freighter is without engines, drifting. So, who the frac knows where that damnable freighter is, or whether we might someday be able to purchase a LOST Physics 101 textbook.