My vessel was heading on a course of 310°, approx 1nm west of Haisborough Sands, at approx 15kts. A passenger ferry was slowly overtaking me, and was 0.5nm on my starboard beam. A vessel heading south was detected early on radar and an ARPA plot made. AIS named the vessel as XXX. A CPA of 0.2nm was given. After closely monitoring the XXX, her CPA did not change, and she approached from almost right ahead. VHF contact was made at 4.0nm to ascertain her intentions as I was limited in my ability to turn to starboard because of the overtaking ferry. She replied “I will keep my course & speed”. I then requested she altered to starboard as I was restricted in my ability to do so whilst she had open water on her own starboard side. No response was heard from XXX despite calling twice more, and she maintained her course and speed. She was less than 3nm away at this point.
I immediately contacted the Engine Control Room and reduced speed to allow my vessel to drop astern of the overtaking ferry, engaged hand steering and altered course to starboard. I also called the master to the Bridge. As our speed reduced I continued to turn to starboard until the CPA with XXX was 0.5nm. Once she was clear speed was increased and original course resumed.
Lessons learned: It was clear from an early stage that my own ability to alter to starboard was restricted due to the overtaking ferry and proximity of Haisborough Sands. XXX had open water on her own starboard side but refused to alter course putting my own vessel in a difficult position.
In many reports we receive there appears to be a reluctance to adjust speed. However, in this report the action of the reporter in slowing down was prudent as it gave sufficient room from the overtaking ship to alter course to starboard to avoid the approaching vessel.
We have alerted the manager of XXX to this incident.