Picture and text by BSU (Bundesstelle für Seeunfalluntersuchung/Federal Bureau of Maritime Casualty Investigation)
On 2 February 2022, the MUMBAI MAERSK, a so called „Ultra-Large Container Ship“ (ULCS2 ), was en route from Rotterdam (Netherlands) to Bremerhaven. The ship had chosen the deep-water route as opposed to the coastal route for its approach. In the course of a turning manoeuvre just before entry into the narrow “Neue Weser” fairway, the ship ran aground on a dumping ground for dredging silt adjacent to the fairway.
During her approach of the narrow fairway section, the MUMBAI MAERSK received the information via UHF that her berth was still occupied, despite existing schedules, but would become free very soon. With a draft of 12.80 m, the ship was tide-dependent. At first, Vessel Traffic Services granted permission for the ship, which was approaching at a speed of 6 – 7 knots, to cross into the next VTS district. Shortly afterwards, however, it was denied entry into the narrow section of the fairway in which neither turning nor encounters between large ships would be possible without problems. The vessel therefore performed a turn before that point (approx. level with buoys 3b and 4b) and proceeded to sail in the opposite direction.
Less than half an hour later, the MUMBAI MAERSK was informed that she could now enter Bremerhaven after all. With the tide window threatening to close, the ship immediately turned back to her original course. The planned manoeuvre failed, however, and the MUMBAI MAERSK ran aground on a dumping ground for dredging silt just south of the fairway.
Due to the sudden "deceleration" of the foreship, which had run aground first, at a speed of almost 10 knots and during a port turn, the stern of the ship entered into a yawing motion. The ship continued to pivot around a longitudinal axis on the grounded foreship. When the MUMBAI MAERSK finally stopped moving after about 20 minutes, it had rotated by more than 180° from the direction in which it had run onto the dumping ground. When the grounding first happened at 23:06 hrs, it was immediately reported to Vessel Traffic Control.