Korean Register studies widening conversion
Korean Register studied the comparative merits of adding 28,8m to the vessel's length, or 5.2m to its beam
The Korean Register of Shipping (KR) has investigated a widening conversion of an 8,600 teu containership for one of its customers, expanding capacity to 10,000 teu.
The feasibility study follows a landmark project carried out by Huarun Dadong Dockyard Co for German ship owner and manager NSB last year. As reported, the MSC Geneva was the first of three NSB vessels to have its beam extended, enhancing capacity from 4,860 teu to more than 6,300 teu by adding 7.56m to the midhsips width.
KR compared the traditional conversion method of lengthening the ship, by 28.8m, with the more recent approach of expanding the vessel’s beam, by 5.2m. The class society analyzed the new vessel’s potential speed, fuel efficiency, maneuverability, anchoring constraints, stability and strength, as well as the cost and time needed for conversion and the size to which the ship could be expanded.
Both options showed a 4% drop in speed after conversion, with the length extension resulting in a vessel one knot faster. A lengthened ship was also shown to consume 5% less fuel than a widened version. But the widening conversion showed improved stability, with almost no need for additional reinforcement to compared to much greater reinforcement needed for a lengthened ship on deck and bottom because of increased hull bending.
The study also showed that the widening conversion would increase cargo capacity by up to 30%, compared to only 15% in the lengthening scenario. A widening project would take twice as long as lengthening, but the reduced steelwork would mean that the total cost of both conversions would be similar. Maneuverability and anchoring would also be similar.
Dr. CW Kim, executive vice president, technical division of KR said: “The cost to complete a ship conversion is only around 15% of the cost of a comparative newbuild and the conversion time required is considerably shorter. Therefore, it can be a great alternative to placing a newbuilding order.”