Bulk Carrier Safety

General

MSC-67 continued its work and progressed regulation governing the safety of new and existing bulk carriers. Discussions centered on the ramification studies carried out by IACS -- at the request of MSC-66 -- which applied new structural criteria to existing bulk carriers. The results were reported to MSC-67 and were used as a basis to determine the extent to which new requirements would be retroactively applied to existing bulk carriers.

IACS Ramification Study

The IACS study applied new structural survivability standards to the transverse bulkheads and double bottoms of a random sampling of over 100 existing handymax, panamax and capesize bulk carriers. As reported to MSC, compliance with the standards was found to be ship-specific and highly dependent on the structural detail and arrangement. However, IACS considered the sampling to provide a good indication of the 4000+ existing bulk carriers with an average age of 14 years and with lengths in excess of the 150 meter lower limit.

The ramification studies showed that the transverse bulkhead between the first two holds is the bulkhead most in need of reinforcement/renewal to meet the IACS standard. Assuming the ship’s holds are alternately loaded, 40% of the bulk carriers evaluated met the standard with “as-built” scantlings. This compliance rate reduces to 24% if 2mm of corrosion is assumed. If, however, the cargo loads are reduced due to homogeneous loading, the percentage of bulk carriers complying increases to 61% and 32%, respectively for 0mm and 2mm of assumed corrosion. Reducing draft, and therefore flooding head, was found to be more effective than reducing the cargo load in achieving compliance or in limiting the extent of reinforcement necessary.

The study also evaluated the double bottom structures and found the midship region to be most critical. Assuming the ship’s holds are alternately loaded, 90% of the bulk carriers evaluated met the standard with “as-built” scantlings and 77% met the standard if 2mm of corrosion is assumed.

Based on the above, Delegates were requested to further consider and evaluate the information provided to MSC-67 so that it may be finalized at MSC-68, June 97.

Enforcement Dates

Prior to MSC-67, the proposed regulations were tentatively agreed to come into force on 1 July 98. However, to allow for the draft regulation to be progressed towards finalization, the enforcement date has now been revised to either 1 January or 1 July 1999, depending on the outcome of MSC-68 (June 97) and a SOLAS Conference which is now scheduled for mid-November 97.

A schedule to phase-in compliance with the requirements for existing bulk carriers has been discussed with the view that the schedule be established based on the ship’s renewal survey in dry dock for three age categories (<10yrs, 10-15yrs and >15yrs). However, this schedule may be affected by the revised enforcement dates noted above.

IACS has agreed that on 1 July 98, the watertight corrugated bulkhead between the first two cargo holds and double bottom in way thereof, in bulk carriers > 10yrs of age are to comply with the standards by the due date of the 3rd special survey, but not later than 1 July 03. Bulk carriers <10yrs of age as of 1 July 98 are to comply by the due date of the 3rd special survey.

Application of Structural Standards

The following provides a summary of parameters governing the application of structural standards agreed by IACS vs those still under consideration by IMO.

New Bulk Carriers

Existing Bulk Carriers

Criteria	IACS	IMO
Arrangement	Single Side Skin	Single Side Skin
Date of Build	<1 July 98	<1 Jan/July 99
Age (yrs)	> 15	> 10/15 (?)
Ship Length (m)	> 150	> 150
Cargo density(t/m3)	> 1.0	> 1.78/1.0 (?)
BHD’s / DB’s	1st	1st/All (?)

Damage Stability Aspects

MSC-67 reaffirmed its previous view that new and existing bulk carriers must be capable of complying with the deterministic flooding requirements due to the assumed flooding of any one cargo hold, taking into account, when relevant, the reduced effects of flood water due to the presence of cargo. It was further agreed that bulk carriers complying with the deterministic damage requirements under the 1966 Load Line Convention need not be re-assessed under the proposed regulation.

However, the MSC was divided insofar as the treatment of ships which meet 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.

Diversity of Views

The underlying principle affecting the extent to which new structural survivability standards should be applied to existing bulk carriers centers on the degree of risk reduction needed to provide an acceptable level of safety.

The mechanisms being considered are: (1) reducing the number of bulk carriers carrying high density cargo which may be susceptible to water ingress; (2) reducing the likelihood of water ingress; and (3) mitigating the effects of flooding, should it occur, in a technically sound and feasible manner.

As summarized in the above table, 11 Members comprising IACS agreed that only the foremost bulkhead (and double bottom in way thereof) should be evaluated under the new standards. This decision is commensurate with the greater risks associated with the forward portion of the ship due to increased dynamic loads and, based on statistics gathered by IACS, recognizing that 40% of the bulk carrier losses over the last 15 years included flooding of the foremost cargo hold.