I am master of a trailing hopper Suction Dredger. On the morning of the incident I was dredging for sand in a dredging area in thick fog. At approximately 0800 the OOW reported a target on radar at a distance of 5 miles on a course of 030T making 9 knots. The CPA of the vessel was shown as 0.1 nm. At this time I was at the end of my southerly run and was in the process of turning to starboard for the run back to the north. My course on the run north was 340T and a speed over the ground of 1.2 knots. My track was approximately 358t owing to the ebb tide. Myself and the OOW continued monitoring the approaching target having identified the vessel as ‘XXXX’. At a distance of 3 miles I attempted to contact the vessel to ask for a clearance of at least 0.5 nm and also to inform him of my operation. Despite making several attempts on Channel 16 there was no response. At this point the CPA of XXXX was still 0.1 nm indicating he would pass under my stern. I was not comfortable with this distance so I decided to abort the dredging operation and lift the pipe clear of the seabed and increase speed with an alteration of course to port of approximately 20°. At the time I was six cables from a navigation buoy. XXXX passed between my vessel and the buoy at a distance of two cables from my vessel. I did attempt to contact him again after he had passed clear but again there was no response. Visibility throughout the incident was less than one cable.
We forwarded this report, without disclosing the identity of the dredger, to the manager of the coaster, who, in turn, followed it up with the master. Whilst the response did not reveal the underlying causes for this close encounter in thick fog, it hopefully served a purpose in letting this master know that his contraventions of the ColRegs had been noted.