Oslo: DNV now offers an Extended Dry Docking service, developed to enable shipowners to extend periods between dry-dockings.

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Developed in cooperation with ship owners and flag states, DNV’s Extended Dry Docking Service project team evaluated in service experience and improvements to hull coating performance, as well as assessed quality of in-water repair and survey technology.

According to DNV’s Geir Dugstad, Technical Director, a combination of these approaches can extend periods between bottom surveys in dry dock for eligible ships to 7.5 years, provided that the consecutive in-water bottom surveys are conducted with satisfactory results during the intervening period. “Safety remains our top priority,” he says. “But we have concluded that compliance with the stringent maintenance regimes and technical requirements will ensure safe, quality operations”.

Dugstad says that the eligibility of vessels will be decided on a case-by-case basis, evaluating technical issues and the performance of the management company. However, as a general rule passenger vessels and ships subject to Enhanced Survey Programme (ESP) will not be accepted for the scheme due to SOLAS regulations and IMO Res.A.744 (18). As the inspection outside of the ship’s bottom is a part of statutory requirements, prior to implementation of the extended dry docking scheme, acceptance from the Flag administration of the vessel must be obtained. No vessel over 15 years of age can participate in the programme.

“In order to be accepted for the scheme, the ship must be provided with a high quality underwater coating designed to last for the extended period. The ship must furthermore comply with the in-water survey provisions in accordance with DNV Rules for BIS notation and have a shafting arrangement fulfilling the requirement for tailshaft monitoring,” says Dugstad. “In addition, the owner is required to demonstrate that a comprehensive maintenance system for hull and machinery is effectively implemented. This will be reflected in maintaining good coating condition (both external and within the ballast tanks) as well as regular maintenance and replacement of cathodic protection anodes.”