MOL Comfort Casualty Report
On The 17 June 2013 a modern 8,110 TEU container ship the MOL Comfort (ex APL Russia), built in 2008 by MHI Nagasaki Shipyard split into two halves while on transit from Singapore to Jeddah (Saudi Arabia). All 26 crew, consisting of 11 Russians, 1 Ukrainian and 14 Filipinos, escaped the sinking ship on two life rafts and a lifeboat. The stern section containing approximately 1,500tonnes of fuel oil sank on 27 June and the fore part which was being towed by a salvage company sank on 11 July 2013 having been partly destroyed by fire.
MOL Comfort Vessel Particulars
Ship Owner: Ural Container Carriers SA
Operator: Mitsui OSK Lines Ltd
Ship Management: MOL Ship Management (Singapore) Pte Ltd
Flag State: Bahamas
Tonnage: 86,692 GT
Length (LWL): 316.0m
Length (LBP): 302.0m
Main Engine: Mitsubishi-Sulzer 11RT-flex96C (62,920 kW)
Propulsion: Single shaft; fixed-pitch propeller
Service speed: 25.25knots
Capacity: 8,110 TEU
Classified: Nippon Kaiji Kyokai (ClassNK)
The ship had seven cargo holds in front of the engine room and two cargo holds aft of the engine room. The ship was the sixth in a series of large container ships built by Mitsubishi Heavy Industries Ltd, Nagasaki Shipyard & Machinery Works. At the time of the accident the vessel was carrying a cargo of 4,382 containers equivalent to 7,041 TEU and was sailing at approximately 17knots. The significant wave height at the time was estimated to be 5.5m with a Beaufort force 7 south-westerly wind
The fracture originated in the bottom of the shell plates of No.6 Cargo hold. At about 07:45hours (GMT +5 hours) water ingress was first detected by the water ingress alarm in the duct keel located near the centre line of the double bottom of the ship. Approximately two minutes later, further water ingress was detected in No.6 Cargo hold located on the double bottom amidships. The crack then progressed up the side shell plating of the ship with the upper deck area being the last part to fracture.
Interim Casualty Report
Following the accident the Japanese Maritime Bureau established a committee to investigate “Large Container Ship Safety.” Despite the Committee’s interim report being published in December 2013 the exact cause of the accident remains undetyermined. The investigation quickly excluded out grounding and/or collision, fire and/or explosion originating inside the ship and brittle fracture originating from the upper deck. The Committee’s investigation concentrated on two potential causes of the accident:
- Buckling of the bottom shell plating due to hull girder loads exceeding the hull girder strength
- Fatigue cracking of welded structure
For a full copy of the Interim report click on http://www.mlit.go.jp/common/001029660.pdf
Bottom Shell Plating Buckling
As part of the investigation a safety inspections were undertaken on the vessels six sister ships and a further four other similar ships. Buckling deformations (both concave and convex) of up to maximum of 20mm were found on the bottom shell plating near the centre line of the transverse section in five out of the six sister ships and in one out of other four of the other similar ships. Although, there were differences in the location, shape and frequency of the bottom shell plate deformations. On the five sister ships the deformations occurred most frequently near the centre line at frame 151 (cargo hold No.6) and frame 182 (cargo hold No.5) near the butt joints of the original hull blocks.
Mitsui OSK Lines have now arranged to undertake work to reinforce the hull structures of these vessels to twice the level required by ClassNK and to instigate extra measures to reduce the stress on the hulls by adjusting water ballast volumes. They have also begun legal proceedings against Mitsubishi Heavy Industries for damages related to MOL Comfort and compensation for having to strengthen the hulls of the sister ships.