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DSEC engineers bulbous bow for refitting

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“Careful planning and adherence to deadlines are essential to pull off a major hull part re-fit during regular drydocking, ” says Young Man Lee, President& CEO, DSEC.

“Careful planning and adherence to deadlines are essential to pull off a major hull part re-fit during regular drydocking, ” says Young Man Lee, President
& CEO, DSEC.

The DSME subsidiary DSEC (Daewoo Ship Engineering Company Co. Ltd.) was awarded the detailed design and engineering work related to fitting a new bulbous bow on HMM’s container vessel Hyundai Brave while it was undergoing regular drydocking at Chinese repair yard Qingdao Beihai Shipbuilding. DSEC President & CEO, Young Man Lee, underlines the importance of planning in such projects. by Brynjulf Freberg, freelance journalist and Hwa Lyong Lee DNV

“The whole project was completed in twelve weeks, including the planning, design development and construction work. Half of this period, six weeks, was consumed by the actual production of the new bow structure. In this case, the owner, yard, classification society and DNV, which had provided the design, all delivered according to tight deadlines.

Bulb replacement on vessel Hyundai Brave during drydocking at Qingdao Beihai Shipyard, China.

Bulb replacement on vessel Hyundai Brave during drydocking at Qingdao Beihai Shipyard, China.

“Timely deliveries by all parties involved in projects like this are the most important prerequisite for success. Furthermore, the transparent inter-communication mode established by the partners at the very initial stage was vital for the successful outcome, ” states the DSEC chief. He con- tinues: “Fitting a new part to an existing structure requires a good fit-up with small acceptance tolerances. The hull form is sensitive information usually owned by the shipbuilder. Access to this information at an early stage is crucial not only for the design of the new bulb, but also to ensure a good match between the existing struc- ture and the new bulb.”

“There are two ways to improve performance while lowering speed. One is to reduce the speed only, keeping the exist- ing propeller. In this case, a new propeller is not needed and it is not necessary to de- rate the M/E.
“The other is to increase the propel- ler diameter to optimise for lower speed and thus reduce the FOC. However, this can only be done if there is enough clear- ance to accommodate a bigger propeller. In this case, it will also be interesting to derate the M/E in order to adjust the M/E rpm to the new propeller’s fea- tures. Such a modification will also lead to associated changes such as modifying the turbo chargers, obtaining Tier II cer- tification and assessment of possible vibra- tion issues.”
It is claimed that de-rating the engine and fit- ting a new design propeller for lower speeds could improve the fuel consumption further. What is your view on this?

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