The New International Standard for Subdivision and Damage Stability of Dry Cargo Ships

The U.S. Coast Guard does not have subdivision or damage stability requirements for dry cargo ships, although for many years the U.S. Maritime Administration (previously the Maritime Commission) has required cargo ships built under their subsidy and loan guarantee programs to meet a one-compartment standard of subdivision. The 1960 International Convention for the Safety of Life at Sea (SOLAS) recommended studies be initiated on the extent to which it would be necessary and practicable to apply subdivision and damage stability requirements, having as its aim the formulation of international standards. After nearly 27 years, in September 1987 the International Maritime Organization (IMO) SubCommittee on Stability and Load Lines and on Fishing Vessels Safety agreed on a set of draft regulations. The IMO Maritime Safety Committee (MSC) in April 1988 approved the draft regulations and published them as MSC/Circ.484. The MSC in April 1989 set the Required Subdivision Index, and finalized the regulations. They are scheduled to be adopted into the 1974 SOLAS Convention in May 1990, and will then come into force in February 1992. On April 6, 1988, an Advance Notice of Proposed Rulemaking, based on the IMO draft regulations, was published in the Federal Register. This initiated Coast Guard action to require dry cargo ships, both U.S. and foreign, to meet the new subdivision and damage stability standard. This paper recounts the problems leading up to the establishment of the new international standard, explains the various factors involved in the formulation of the probabilistic method of measuring subdivision, and explains how to apply them to the design of ships.