A 300m cargo ship was fully laden with iron ore when she suffered significant damage to her hull structure following a collision in the Suez Canal. The ship continued to Singapore, however the resultant draft and trim meant there was too much risk in continuing passage to the final destination in China. Dry docks were not a viable option due to the location and condition of the vessel.
UMC assessed the feasibility of an afloat repair. The key challenge was the extent of damage combined with technical and operational constraints at 20m depth. In addition, environmental conditions would prove testing, with the combination of strong tides, poor visibility and a heavy seastate.
UMC designed two cofferdams, which were subsequently built by a local yard in Bintan. These were both sizeable, the largest being 5.5m x 3.5m. The dive team templated the damaged areas and the cofferdams were refined accordingly. They were transported to the ship via a barge and positioned in place with rigging and diver intervention.
The cofferdams were temporaily attached to the hull with underwater welding to establish a 'soft' seal. A hydrodynamic seal was achieved following dewatering. This allowed engineers to enter the damaged area, perform internal repairs and secure the cofferdams to the hull more firmly. Once completed to the satisfaction of the Superintendent, the vessel transited, with the cofferdams in situ, across the South China Sea to its destination port.