Feature 8 | FINLAND
and the emergency generator), air conditioning, navigation, sewage and oil recovery systems were totally replaced. A new accommodation block, containing cabins for the master, chief engineer and on scene commander, was built above the wheelhouse deck, which was modified so that the new wheelhouse layout is asymmetric, creating good visibility aſt and forward. Te new oil detection system onboard
(based on x-band radar) is expected to improve the ship’s capability to recover oil at night and in bad visibility. (Te Finnish national oil pollution response strategy is based on mechanical oil recovery according to Helsinki Convention. Finland does not use dispersants and all government-owned pollution response vessels are equipped for independent oil recovery by means of permanently fitted oil recovery brushes inside the ship.) Also ORV Halli was equipped with a new oil collection system with brushes and telescopic booms. The ship’s hull had been observed to
be insufficiently stiff and, when driven in bigger waves,
the vibration level in
the superstructure was too high. For this reason additional steel structures were designed for the hull and fitted to the lower part of the superstructure. In addition the bottom plate was replaced in a few places because of damage caused by corrosion. Te ship became heavier because of the
new equipment, added steel and aluminium and it lost its some of its buoyancy because of the incorporation of a new box-cooler system. All of this decreased the amount of deadweight, but the loss was smaller than estimated, at 60tonnes. To design a new system is always a
challenge, especially if the new solution differs greatly from those used previously. It was originally planned that the Halli’s classic oil recovery system, consisting of two side doors with water circulation, would be changed to a system where water and oil flow in through the side door and water is pumped out, but that decision was in the end reversed. The two-door system was retained but the aſt door was replaced with a wider door and the water circulation made more effective with the help of propeller pumps. With the fitting of new telescopic booms the sweeping width of the ship has been increased by a few
54
The front bulkhead of the ship before (above) and after the modernisation. (Photo Jukka Pajala).
metres, to 40m now. The new brushes were tested in the
laboratory of the Finnish Environment Institute and compared with brushes from the old collection system. With light oil (300mm2
/s) the new brush design was
shown to be 20-50% more effective than the old one and the prediction for total oil recovery performance at a ship speed of one knot is about 35m3
also to identify any latent discrepancies that might qualify for correction under the guarantee provisions of the contract. Repairing and modernising a ship of this
type is a complex and dynamic process with a high level of interdependency between the various partners. Output quality is significantly influenced by the quality of the assessments and decisions that are made and cannot be ensured only by sticking to certain predefined procedures. Expert knowledge and experience have a decisive role to play, and this required the project organisation to have a very wide scope. Not only the ship’s crew, but also experts from Navy headquarters were involved in the project for example, while the Finnish Environmental Institute’s pollution response section contributed specifically to the design and installation of the oil recovery systems. Although old design material was used
in the project, in total 496 new drawings were prepared at the design stage by the shipyard. Every drawing was inspected and commented on by the project group, within a short time frame. Moreover everybody in the project group understood that once things were decided, that was the final decision. The cost of the modernisation was
/h, based on an oil
layer thickness of 0.5mm. With that level of performance the vessel’s oil tanks, with a relatively high total volume capacity of 1300m3
, could be filled in 37 hours. Halli was docked at STX Helsinki in
November 2009 and after sea trials in May last year, she was redelivered to the Navy in June 2010. As of January 2011 the vessel was still undergoing a period of tests and trials to confirm the capabilities and limitations of the ship, to bring the ship from a state of contractual completion to one of full material readiness. These post-delivery tests and trials are designed
around €12 million in total. In addition to the contract price, there were also costs generated by project management, inspections and travelling (2.4% of total). During the project some small changes were made to the contract specification and, of course, some surprises in the ship’s condition were encountered. Such extra work added around 2.5% to costs, but because of some reductions that were made to the contract specification, the total additional costs represented only 1 % of the total in the end. Te modernisation project is considered
successful by all concerned. Te cost of modernising Halli was approximately one-third of the cost of a new ship while, most importantly, the work was carried out within a period of 11 months. By comparison a new ship would take 2-3 years to design and construct. SCRT
Reference Tis article was written by Jukka Pajala, of the Finnish Environment Institute.
Shiprepair and Conversion Technology 1st Quarter 2011
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