1 In view of a wide variety of ship types, sizes, operational profiles and environmental
conditions, the problems related to dynamic stability failures have generally not yet
been solved. Administrations should be aware of the fact that some ships are more at
risk of encountering critical stability in waves. The Administration may, for a
particular ship or group of ships, apply dynamic stability criteria which demonstrate
that the safety level of a ship in waves is sufficient.
2 For this purpose, performance-based criteria for assessing five dynamic stability
failure modes in waves are provided in these guidelines, namely, dead ship condition,
excessive acceleration, pure loss of stability, parametric rolling and
surf-riding/broaching.
3 The physics and evaluation methods for these five stability failure modes had not been
well understood or developed when the mandatory intact stability criteria were
established. As such, the herewith presented dynamic stability criteria utilize the
recent progress using best practices and the most advanced scientific tools available,
for practical regulatory-oriented application. Accordingly, the background of the
dynamic stability criteria is principally based on first principles and latest
technology, as opposed to predominant use of casualty records which form the basis of
the mandatory intact stability criteria. For this reason, the presented dynamic
stability criteria may be considered as the second generation intact stability criteria.
4 The methodologies contained in these Interim Guidelines are based on general
first-principle approaches derived from the analysis of ship dynamics. However, in the
development process, it was also necessary to simplify some of the assessment
methodologies and to perform some semi-empirical tuning.
5 In developing the framework of these Interim Guidelines, it was recognized that an
integrated perspective, combining design methods and operational measures, is the most
effective way for properly addressing and continuously improving safety against
accidents related to stability for ships in a seaway.
6 Therefore, the second generation intact stability criteria should be used for helping
to ensure a uniform international level of safety of ships with respect to dynamic
stability failure modes in waves.