scanners to reduce the time and cost associated with installing ballast water management systems (BWMS) on existing vessels. Te process is of concern to ClassNK,
which observes that: “Once the ballast water management convention is adopted, tens of thousands of vessels will need to be retrofitted with ballast water management systems in a short amount of time. As a result, increasing the efficiency of retrofit design and installation will be absolutely essential.”
ClassNK believes that 3D scanners
are one tool that has a great potential for increasing the efficiency of the entire retrofit process. In order to determine the practical applicability of 3D laser scanners to reverse engineering, this project carried out investigative research on a variety of potential uses for 3D laser scanning technology, including not only the retrofit of BWMS on existing vessels, but also repair of existing vessels and survey work.
For ballast water retrofits on existing
vessels specifically, this project investigated and confirmed a variety of factors in order to establish effective procedures for the use of 3D laser scanners in the design and installation of BWMS retrofits. Tis research has confirmed that there is a commercially viable business model for the use of 3D laser scanners in marine engineering work, and also identified several key problem areas that need to be resolved for that model to be successful. SRCT
Specific ships for specific tasks
RINa highlights the role it can play in conversion projects to ensure operators get the vessels they require for particular deployments.
and is deploying that knowledge to help owners get the ship they want to do the task they need. Dino Cervetto, head of technical services, RINa, says: “In the OSV field, owners want very specific vessels and characteristics, fit for specific tasks. We have recently updated our rules in that area and have overseen some interesting conversions in China, to help achieve that objective.” The conversion of Halani I was an
I
unusual, but successful example of the society’s involvement in a vessel conversion process. The owner took a Dutch ferry and converted it under RINA class to a 95.8m long multi-role OSV. Cervetto says: “Te Indian operator Halani Shipping wanted a flexible and capable vessel to perform a variety of support activities in the offshore field. Tis conversion shows how a hull designed for one job can do something completely different if it is worked out properly.” The conversion work took place at
the Hongzhou Shipyard in Zhejiang Province and took around 21 months to complete. One of the major challenges was to ensure structural integrity aſter cutting large holes for the moonpool and thrusters, and to support the load from the two large deck cranes, which can liſt up to 100tonnes. Extensive analysis of
talian classification society RINa has significant experience of conversions in Chinese shipyards
Halani 1, a 95.8m multi-role OSV converted under RINa class for Indian owner Halani Shipping.
the structure was carried out, and local reinforcing fitted. Altogether, about 1400tonnes of extra steel were fitted to the ship. According to Cervetto: “Te open nature of a ferry structure helps outfitting decisions, but does require careful stiffening when you cut holes in it or mount cranes on top of it. ” There were also some interesting
decisions to be made on the dynamic positioning (DP) system retrofit. This included determining the optimum size of thrusters, where to site them and how to deliver power to them. Te vessel is now in service using its
crane and its 4-point anchoring system to perform topside jobs. With its dynamic positioning capabilities, the vessel has also supported remote operated vehicles
Shiprepair and Conversion Technology 1st Quarter 2012
(ROV) operations down to depths of 85-90m. Te conversion made provision for an onboard workforce of 250 persons, which was needed to support offshore maintenance work. RINa certified the vessel for the
delivery voyage from Te Netherlands to China, where it was rebuilt with extensive modifications. Tese included the fitting of six thrusters, a fire-fighting system with a water spraying protecting system, a large moonpool, two 100m telescopic cranes, a heave- compensated telescopic gangway and, crucially, very efficient DP3 dynamic position capability. The vessel also has full automatic positioning and tracking with a high level of redundancy and margins of performance. SRCT
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