Conservator or Innovator? Prescriptive vs. Function based Classification Rules

Thomas Revheim

Det Norske Veritas Pte Ltd, Singapore



The Offshore Support Vessel (OSV) segment is a highly technology and innovation driven ship segment. The developments in equipment, control systems, power generation and even hull shape prove that the OSV segment is extremely competitive with respect to design, research and innovation. How do class societies adapt to the changes? Are they perceived as “brakes” or “fuel” in the race to win the market share for owners, operators or shipyards? Our customers ask for a more flexible approach towards market needs, due to a diverse market. Safe and efficient operations are interpreted differently depending on variation in environmental and working conditions. Consequence of failure varies (deep water, harsh environment versus benign, oil & gas related versus offshore wind field support operations).

Current status

IMO has initiatives regarding goal-based rules, not dissimilar to function based rules. The intention is that IMO will be responsible for the goals and the functional requirements, whereas Class shall be responsible for the prescriptive rules to satisfy the goals. However the problem arises that increased amounts of novel designs which are not covered by prescriptive regulations coupled with a lack of goals for specific systems, leave gaps between IMO’s goals, present prescriptive rules/regulation and current best industry practice. Most class rules are prescriptive and to a very little extent function based. DNV has, however, published function based rules for “Machinery General” (Pt.4, Ch.1).

Way forward

DNV wants to be a technology and innovation accelerator in the race for better ships. The anchor handling, tug and supply OSV(AHTS) may be worth a case study for function based rules, and DNV’s latest major rule update for this ship type already adopts much of the philosophy behind this approach to ship design and approval.

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