Trans RINA, Vol 153, Part A1, Intl J Maritime Eng, Jan-Mar 2011


SOLAS 2009 STABILITY REQUIREMENTS: IMPLEMENTATION J Dodman, Lloyds Register EMEA, UK SUMMARY


January 2009 saw the introduction of substantial changes to SOLAS, commonly referred to as SOLAS 2009. Not only have significant parts of Chapter II-1 completely changed, but so have the methodologies for assessing survivability of certain ship types.


This paper provides an overview of some of the main topics and how Lloyd’s Register is adapting to provide necessary industry solutions and support, immediately and into the future. It provides an insight into the probabilistic requirements, our approval processes, developments and our participation in defining industry standards.


It is evident in this paper that the discussions predominantly revolve around passenger ships. This is due to their complexity and the conflict between the new regulations for survivability assessment moving from a restrained deterministic requirement to a risk-based probabilistic solution. It also highlights real issues over the difficulties of implementing this methodology. This conflict in overall design is less pronounced for dry cargo ships, which did not have to comply with a general damage stability standard until 1992 when the probabilistic concept was introduced for dry cargo ships only. Under SOLAS 2009, a modified requirement has been implemented. However, the fundamental issues remain the same.


NOMENCLATURE


A Attained index. As Ap Al R pi


si 1.


Attained index at deep subdivision draft. Attained index at partial subdivision draft. Attained index at light service draft. Required subdivision index.


Probability of a compartment or group of compartments being flooded.


Probability of survival after flooding. INTRODUCTION The SOLAS 2009 harmonised damage stability


regulations under Chapter II-1 have been a long time in development. On January 1, 2009, the new damage stability regulations came into


Resolution MSC.216(82) with supporting explanatory notes contained in IMO Resolution MSC.281(85).


Probabilistic damage stability was introduced for dry cargo ships greater than 100 metres in length from 1992. At that time, a proposal was put forward at the IMO to extend this method of damage stability to passenger ships as a replacement for the existing deterministic requirements.


On the platform of the extensive work carried out by the EU funded HARDER project, existing statistical casualty databases were updated, substantial model testing was carried out and methodologies were reviewed to arrive at the new SOLAS 2009 requirement we have today. The intent was to provide a harmonised


system for


determining survivability for dry cargo and passenger ships, while maintaining the current and accepted level of ship safety. In a pure sense this is quite simple but the


force under IMO Figure 1: IMO development of SOLAS 2009.


IMO Resolution A.265(VIII) was introduced in the 1960s and provided an alternative option for passenger ship survivability assessment under SOLAS 90 (i.e. SOLAS 74, including amendments pre January 1, 2009). This


regulation was ahead of its time in using a


probabilistic approach. For passenger ships in general it proved unpopular and stringent, which explains why developments over the past 40 years focused around improvements and amendments to the deterministic SOLAS damage


stability requirements. Resolution


A.265(VIII) has generally been applied to vessels with a limited number of passengers and with lower holds where the main transverse bulkheads do not extend uniformly up to the bulkhead deck continuously from side to side, making it difficult to comply with the floodable length requirements. The new SOLAS 2009


SOLAS2009 Revised SOLAS Chapter II-1


Harmonised Regulations for Passenger & Cargo ships Probabilistic


huge variation in ship configuration and operations, together with varying associated levels of acceptable and perceived risk, ensure this task is not so straightforward. Figure 1 demonstrates how existing regulations were encompassed into the new SOLAS 2009.


IMO Res. A.265


(SOLAS equivalent) Passenger ships Probabilistic


SOLAS – Ch. II-1


Passenger ships Deterministic


SOLAS – Ch. II-1 B-1 Cargo ships Probabilistic


©2011: The Royal Institution of Naval Architects


A-1

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