201463 Near miss at anchorage

Own vessel was at a busy anchorage in calm weather and excellent visibility with three vessels anchored on our starboard side, the nearest at 0.7 nm. Additionally, two vessels were anchored on our port side,  the nearest about 0.5 nm. The nearest vessel on the port side picked up anchor and proceeded to board a pilot. The vessel was observed to alter course to port and it appeared she would pass between own vessel and another anchored vessel. At first this manoeuvre appeared safe. But the vessel continued altering to port such that she would pass close ahead of own vessel.

Own vessel’s crew called on the VHF to warn the manoeuvring vessel that she would be passing too close and to keep a greater distance from our bow. The manoeuvring vessel acknowledged, but continued to cross the subject vessel’s bow at distance of less than one cable. 

Master and/or pilot of the manoeuvring vessel did not consider two things:
* The tidal current could bring the vessel closer than their calculations; passing so close can cause a collision.
* The anchor chain of the anchored vessel may be stretched. Should it come into contact with the manoeuvring vessel, this could cause undesired interactions and possible contact between the vessels.