During the past decade, the maritime industry has seen two major initiatives with the potential of radically changing its regulatory system. One has significantly enhanced ship safety; the second has yet to prove its worth.
Formal Safety Assessment (1995) and Goal-Based Standards (2002) were initiatives taken at the International Maritime Organisation (IMO), as part of its responsibility for developing international safety and environmental-protection regulations. DNV Research has been actively involved in most of the FSA studies used for decision making at the IMO, and observe that there are clear benefits in following a rational decision process where hazards are identified, risks analysed and quantified, potential risk-reducing measures identified, and both the risk reduction and costs of the proposed measure documented.
In the case of Formal Safety Assessment, we have seen remarkable risk reduction for very little cost: for example, the work on bulk-carrier safety reduced the risk of loss of life by about two thirds. On the other hand, the initiative by Greece and the Bahamas in 2002 on Goal-Based Standards has a less clear motivation, as have its various supporters. The main activity at the IMO has so far been focused on defining high-level goals and functional requirements which the Classification rules must fulfil, and a process for verification of these rules. It is therefore important for the Class societies that such goals and functional requirements are based on a rational and clearly defined approach, not on arbitrary or politically motivated decisions.
It is not at all obvious what the result of the GBS development will be. So far it has been agreed that goal-based standards should be:
- Broad safety, environmental and/or security standards which ships are required to meet throughout their life
- Of a level to be achieved by the requirements applied by Class societies, the IMO and other recognised organisations
- Clear, demonstrable, verifiable, long-standing, implementable and achievable, irrespective of the ship design and technology
- Specific enough not to be open to differing interpretations.
The GBS system is proposed to have five tiers. A draft Tier II (functional requirements) has been tentatively agreed, but so far only for bulk carriers and tankers. For example, a 25-year design life has been provisionally specified. This is new, as rules previously expressed minimum requirements irrespective of age, and total life was viewed according to how the ship was operated and maintained.
Today most bulk carriers and tankers already have a commercial life until scrapping of about 25 years – though there have been poorly designed ships scrapped before they reach 15 years. When the majority at the IMO insisted on specifying 25 years design life, this was perceived as an increase from 20. However, this is based on a misunderstanding. 20 years life in the Classification rules refers to the return period for extreme wave loads, not design life, and the difference between
20 and 25 years (North Atlantic) is only 1.4%.
Other Tier II elements relate to environmental loads, intact strength, fatigue, residual strength, coating, corrosion, structural redundancy, watertight integrity, design transparency, construction, construction surveys and maintenance. Most alarming is the fact that the GBS development is without a well-defined approach. For example there is no requirement indicating the acceptable safety level, which could be used to determine net scantlings. DNV Research has therefore had to demonstrate basic methods that link high-level safety objectives to structural strength (MSC 81/INF.6).
We are of the opinion that the development of GBS is a logical consequence of using FSA as the basis for rule development, and Structural Reliability Analysis as the basis for the detailed rule calibration procedure. At MSC 81 (May 2006), there will be extensive debate on whether GBS should be risk-based or not.
Date: 2006-03-13