Ok lets speculate and I may be wrong of course. There is a video on Casual Navigation utube channel and the clip makes sense to me regarding bank effects . I cut a little piece here:
This could be a cause of initial swing to starboard. It is hard to guess what they did with the helm seeing this , so I do not know what they did .
From the “Full video clip” one can see the swing to starboard continued and then accelerated. Some say due to starboard helm, some say due to M/E full astern action. Who knows?? As I do not know.
We know the Pilot ordered port anchor to let go and they did it. And surely they did it ,when the vessel was swinging to starboard. Intention was to halt the swing and slow the vessel.
Is it possible, that letting go port anchor during the swing was not only counterproductive but it exacerbated the starboard swing . ???
I have made an akward drawing to better show what I mean . The anchor with the chain surely went under the hull during the swing. When it cought ground from time to time it could have created temporary “pivot points” that exacerbated the starboard swing instead of stopping/halting it .
I have not such an experience , therefore it is purely hypothetical scenario and I may be totaly wrong , hence the pilots comments would be most welcome. Black asterisks symbolise “temporary pivot points” .
Sounds crazy but who knows??? Now over to experts.
Addendum:
Can somebody verify this :
QUOTE:
The ship was not “In the Channel”, they were “In Port” and there are regulations that dictate the speeds that a vessel of any size may move within that area of operations. In this case, the regulation for a ship exceeding 10,000 gross tons is no greater than 3 knots until they clear the Key Bridge and are “outside” the port. So WHY was the ship traveling at 9 knots?
END QUOTE
THX