Ok, but doesnt both radar and AIS calculate collision based on points over ground?
2 objects in the same place at the same time?
Rarely do small boats give a constant visual of lights at sea in all but calm conditions to worry about the transition back and forth of nav lights...if on that border, most would assume the worst and manuever accordingly. I would never use the sectors for collision as much as constant bearing decreasing range...the real indicator in my mind of a collision.
Bigger ships that I served on strictly ran radar and maneuvering board plots of constant bearing decreasing range so not really either sog or stw mattered in my mind. But that was way before much of the last 2 decades of tech happened, but they didn't worry anout lights all that much in determining actual collision, and open ocean currents really werent all that interfering.
I understand what you are saying, just never saw any practical use including collisions for stw. Guess I have never been in areas with that much current and such slow speeds that would cause that much crabbing and make it that confusing. Usually in those areas, bigger vessels are following traffic schemes or channels and smaller vessels can close pretty close before it becomes a situation.
But yes........ if the tech is there....it would be handy....but I have never experienced nav gear that sophisticated.
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