The Byakko sank at about 2:40 a.m. after colliding with the chemical tanker just before midnight in the Kurushima Strait, Chief Cabinet Secretary Katsunobu Kato told a news conference.
Kurushima Strait is on Japan’s Seto Inland Sea, heavy ship traffic, mix of coasters and deep-sea vessels.
The Strait has very strong tidal currents and is a bit tricky to navigate. Depending on the tidal current at times the ships pass port-to-port or stbd-to-stbd. The information wrt which arrangement is in force is passed to mariners using “traffic lights” at each entrance.
A Study of Instruction on the Special Passage Track During Change of Tide in Kurushima Traffic Route: The Location Where the Instructions Were Issued and the Accompanying Shift of the Navigation Route