The 19,400-dwt Rickmers Dubai (built 2011) hit the un-manned crane barge Walcon Wizard, which was being towed by the tug Kingston, in the south-west traffic lane of the Dover strait in the early hours of 11 January.
The accident occurred as Rickmers Dubai was overtaking the tug and its tow, the Marine Accident Investigation Branch (MAIB) said.
After the clash, the towline caught on Rickmers Dubai and Kingston was towed stern-first through the water until the towline ran free from its tow winch.
Walcon
