Photo: Hydrex Propeller straightening proceedure in progress.


planned maintenance scheme for hull and machinery needs to be im- plemented as part of the extended dry-dock interval. And, of course, the Flag State has to approve the extended dry-dock interval of 7.5 years. All in all not a bad thing when you are able to reduce your other- wise minimum five-yearly interval by 50 percent, with the obvious cost savings to go with it. There are numerous underwater


repair and maintenance experts around. The bigger ones are com- panies such as Aegir Marine of the Netherlands, in particular for tube


Underwater propeller repair taking place.


seals, bearings and tail shaft repairs, and Hydrex of Belgium. Aegir is the only Class-approved stern seal service company in the world and, as mentioned, these kind of repairs can be carried out anywhere in the world, at very short notice. Aegir, for example, has offices in the Nether- lands, Singapore, the U.S., Namibia, and Shanghai. (www.aegirmarine. com) Underwater repair and mainte-


nance, particularly with respect to vessels, is perhaps underutilized. It is surprising that rules and regula- tions have not been adopted to


allow for more widespread utiliza- tion of this technology, considering it is used for other underwater steel and mechanical structures such as underwater pipelines, bridges, tun- nels, steel-supported wharfs, locks, gates and valves, offshore produc- tion platforms and underwater oil and gas production equipment that are protected by paint systems and equally subjected to corrosion. Why can these structures be main-


tained and repaired under water without having to be inspected ‘dry’ frequently?


n


Photo: Hydrex 9


September 2013


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