It seems to me that if the vessel was observed as you outlined it would have to be a visual or radar sighting. It also is clear that whatever system...
I seem to remember P31 was on standby after the Kowloon Bridge incident to sink another merchant vessel adrift should it be in danger of drifting on...
Not sure if my phone recording would be of high enough quality to make it to the DF YouTube page, where something like this could be easily accessed....
A derelict found at sea, is reportable, and a decision on it's fate is a priority. In this case an unlit object weighing more than a 1000 tonnes and...