Bulk Carrier Safety

General

MSC68 finalized draft regulation governing the safety of new and existing bulk carriers. Central to the discussions were the new IACS Unified Requirements containing structural criteria for new and existing bulk carriers.

The draft regulations, which are subject to approval by the SOLAS Conference scheduled for November 1997, are proposed to come into effect on 1 July 1999 unless more than one third of the Contracting Governments representing 50% of the gross tonnage of the world’s fleet registers an objection.

An overview of the draft regulations, which will be contained in a new Chapter XII of SOLAS, requires all new bulk carriers, regardless of configuration, built after 1 July 1999 to have sufficient stability (as required by the 1966 Load Line Convention’s deterministic approach) and strength (based on IACS Unified Requirements) to withstand the flooding of any one cargo hold including dynamic effects prior to carrying cargo having a density > 1.0 tons/cubic meter.

Existing single side skin bulk carriers built before 1 July 1999 must have sufficient stability (as required by the 1966 Load Line Convention’s deterministic approach) and strength (as required by IACS Unified Requirements) to withstand the flooding of the forward most cargo hold including dynamic effects prior to carrying cargo having a density > 1.78 tons/cubic meter.

Comparison of IACS and IMO Standards

The following provides a summary of parameters governing the application of standards agreed by IACS vs the draft IMO SOLAS regulations.

  New Bulk Carriers

Criteria	I ACS	IMO
Arrangement	Single Side Skin	All types
Contract Date	> 1 July 98	---
Keel Lay Date	---	>1 July 99
Ship Length (m)	> 1	> 150
Cargo density(t/m3)	> 10	> 1.0
BHD’s / DB’s	All	All

As can be seen, the major differences between IACS and IMO requirements is with regard to the compliance date schemes, as discussed below, and IMO’s extension of the IACS requirements for single side skin configurations to apply to all types of configurations of new bulk carriers. Also, there are slight differences in the definition of length to be used.

  Existing Bulk Carriers

Criteria	I ACS	IMO
Arrangement	Single Side Skin	Single Side Skin
Contract Date	<1 July 98	---
Keel Lay Date	---	<1 July 99
Age (yrs)	> 15	>20 & >15
Ship Length (m)	> 150	> 150
Cargo density(t/m3)	> 1.78	> 1.78
BHD’s / DB’s	1st	1st

The only significant difference between the two standards is the compliance date schemes, as discussed below.

Flooding Stability Standard

New bulk carriers, after flooding of any one cargo hold, and existing bulk carriers, after the flooding of the foremost cargo hold, must comply with the damage equilibrium conditions of the 1966 Load Line Convention, as amended by Resolutions A.320(9) and A.514(13).

These resolutions call for the final equilibrium waterline to be below all deck openings, leading to buoyant spaces, which are protected by weathertight/watertight covers except bolted/gasketed manhole covers and remotely operated sliding watertight doors.

Further, the ship must retain a positive GM after flooding and possess a righting arm (GZ) curve with a range, magnitude and area beyond equilibrium of at least 20o, 0.1 meters and 0.0175 meter-radians, respectively.

Alternative Stability Standard

MSC68 reaffirmed its previous view that compliance is to be determined based on deterministic flooding requirements and therefore did not accept that the probabilistic damage requirements of SOLAS Part B-1 -- which, due to its inherent methodology, does not explicitly ensure that the ship can survive the flooding of any single cargo hold – can be considered as demonstrating compliance with the above flooding criteria.

However, new and existing bulk carriers, assigned a reduced freeboard and remaining afloat in a condition of equilibrium as defined by Resolutions A.320(9) and A.514(13) (see above) after applying the deterministic “beam/5” damage penetration requirements under Regulation 27(7) of the 1966 Load Line Convention, need not be re-assessed under the proposed Flooding Stability Standard discussed above.

Existing bulk carriers, assigned a reduced freeboard and remaining afloat in a satisfactory condition of equilibrium after applying the deterministic “beam/5” damage penetration requirements under Regulation 27(7) of the 1966 Load Line Convention, need not be re-assessed under the proposed Flooding Stability Standard discussed above.

Implementation Schedule

Structural and Stability Requirements

To allow for a period of compliance and considering the risk associated with bulk carriers

The above implementation differs from IACS’ which requires that bulk carriers built on or after 1 July 1988 must meet IACS retroactive requirements by the 3rd (or above) periodical (special) survey due date, but not later than 1 July 2003. Bulk carriers built after 1 July 1988, but before 1 July 1999, must meet the retroactive requirements by the 3rd special survey due date.

Because IMO specified either the 1st intermediate or periodical survey due date, the IMO criteria may govern for ships more than 20 years of age.

Survey Requirements

Single side skin bulk carriers > 10 years of age on 1 July 1999 must have carried out an enhanced special survey, or an equivalent survey of all cargo holds prior to carrying bulk cargoes with a density > 1.78 tons/cubic meter.

IACS Members previously agreed to implement the above provisions to bulk carriers, except without regard to the density of bulk cargoes carried, such that the survey of all cargo holds shall have be completed by 1 January 1998.

Other Requirements

To more efficiently calculate actual hull girder shear forces and bending moments and readily compare the values with the permissible limits, loading instruments

Additionally, prior to loading any solid bulk cargo, the shipper is to provide a declaration of its density, if it is within the range of 1.25 to 1.78 tons/cubic meter, based on the verification carried out by an accredited organization.

Certification / Endorsement

To indicate compliance with the standards, the loading booklet (required to be on board all bulk carriers by 1 July 1998) containing stability and structural limits and any loading/unloading restrictions, is to be endorsed to indicate compliance with the stability, structural and survey requirements as noted above. Additionally, a solid equilateral triangle is to be permanently marked 300mm below the deck edge, at amidships, on both sides of existing single side skin bulk carriers which have loading restrictions on the amount and distribution of cargoes > 1.78 tons/cubic meter.

Exemption Provisions

Single side skin bulk carriers > 150m and carrying solid bulk cargoes with a density > 1.78 tons/cubic meter which have been built prior to 1 July 1999 may be exempted from the requirement to sustain flooding of the first cargo hold if they were constructed with an insufficient number of transverse bulkheads. However, annual close-up surveys of the foremost cargo hold shall be carried out under the requirements of the intermediate enhanced survey. Further, visual and audible high water bilge alarms shall be fitted in all cargo holds and information on cargo hold flooding scenarios with evacuation preparedness training, drills and programs shall be provided.