Too often we hear of ships colliding at sea, but did you know that most ship collisions happen in coastal waters, inlets, ports and channels? It is similar to the theory that most car accidents happen within 10-miles of the home, while the most actually happen in parking lots at very low speeds.
In the open sea, ships use radar to navigate and prevent collisions; that makes sense. But in channels the tolerances to other ships is so close that the navigators and captains must watch out and use their skills to navigate. Of course if they reckon wrong they are dead, or rather run aground, collide with another ship and lose their jobs.
To prevent these maritime accidents a new method has been devised to use radar assisted anti-collision techniques, by carefully setting a narrow band view of the radar to get precise readings that are relevant without the 360 degree wide view of the normal radar display. In the CPA (closest point of approach) technique the mariner would set the VRM or variable range marker at only distance of its speed divided by a ten. This allows him to establish the minimum distance the vessel needs to clear the point and gives him six minutes to adjust.
By using the skill of the mariner plus the data of the radar, more ship collisions could be prevented. And if this data were fed to a localized receiver (consider a Transponder for aviation) then that data could be sent to the other ship and actually a robotic system could insure no collisions in such close proximities and close quarters. Consider this in 2006.