IMO SDC 4 still tied-up on the development of new regulations and guidelines for safe mooring operations


BIMCO attended the 4th session of the IMO Sub-Committee on Ship Design and Construction (SDC 4), which was held in London from 13 to 17 February 2017.

This is a short summary of the main issues arising from the meeting:

Unified Interpretation to provisions of IMO safety, security, and environment-related conventions

During the meeting, SDC 4 agreed on a number of unified interpretations based on IACS proposals:

  • draft unified interpretations regarding drainage of enclosed spaces situated on the bulkhead deck, including special requirements for vehicle ferries, ro-ro ships and other ships of similar type. The interpretation should be provided with doors (including stern, bow and side doors) or covers considered watertight in relation to their position (Ref. SOLAS II-1/17-1.1.1 and SOLAS II-1/20-2);
  • draft amendments to IACS unified interpretations (UI) SC191 related to the application of SOLAS regulation II-1/3-6, setting out technical provisions for means of access for inspections (see IMO resolution MSC.158(78)) and of the performance standards for water level detectors on bulk carriers and single hold cargo ships other than bulk carriers (see IMO resolution MSC.188(79));
  • draft guidelines on the means of access to structures for inspection and maintenance of oil tankers and bulk carriers according to SOLAS XI-1/2. This is a “housekeeping issue” which provides recommendations on the access to tanks, cargo holds and ballast spaces to enable the hull structure to be examined in a safe and practical way, when the overall and close-up surveys are being performed. (Ref. 2011 ESP Code (IMO resolution A.1049(29)).

Furthermore, SDC 4 had extensive discussions on:

  • the draft regulations if a deadweight at a trimmed waterline exceeds the even-keel deadweight, and in such case what should be written at the ships' certificates. 

SDC 4 was unified in their understanding that even-keel hydrostatics should be used to determine the regulatory deadweight for the relevant statutory certificates. But the sub-committee did not agree whether or not it was acceptable for loading manual and stability information to include a loading condition at a trimmed waterline that exceeds the even-keel deadweight. As SDC 4 could not agree on this part, it was referred to the next meeting for further discussion.

New guidelines for safe mooring operations for all ships

DSC 4 continued the development of new regulations and guidelines for safe mooring operations. 

An amendment to SOLAS regulation II-1/3-8 was not agreed upon at this stage, and it was also decided that the guidelines would have to be developed further. 

The SDC 4 decided to establish a correspondence group to continue the work applicable for new ships above 3000 GT and submit a report to the next session of the sub-committee.

BIMCO will participate in the work to come.

Second generation intact stability criteria

SDC 4 also reviewed a set of new intact stability criteria. The development covered requirements and criteria for the five different stability failures modes (pure loss of stability, parametric roll, surf-riding/broaching, dead-condition and excessive accelerations). 

The general work was based on a three-level approach covering different stages of vulnerability:

  • “level 1” criteria checks the vulnerability of a ship to a specific dynamic failure mode 
  • “level 2” criteria indicates the degree of vulnerability to the particular failure mode. 
  • “level 3” contains numerical tools for direct computations including minimum qualitative and quantitative requirements. 

The intention has been to provide a set of simple and easy applicable criteria at the first two levels to identify conventional ships, for which the existing intact stability criteria work well. The criteria of “levels 1” and “level 2” are based on significant simplifications and have been developed based on substantial safety margins.

Until now, the work has been focused on the development of “levels 1” and “level 2” criteria and standards.

At SDC 4 it was decided to start the development of draft guidelines for the direct stability assessment (level 3) as this would lead to the necessary calibration of “level 1” and “level 2”. Although SDC 4 did not finalize the work, a set of draft guidelines was established. The guidelines include procedure requirements and acceptance criteria for a quantitative validation. 

Furthermore, SDC 4 agreed that explanatory notes for vulnerability criteria and guidelines for operational limitation should be developed in the future. The intention is to submit all the regulations and guidelines as a package to MSC 102 in 2020 with view for adoption/approval.

Damage stability

SDC 4 also worked to finalize a package of draft amendments to SOLAS chapter II-1 on subdivision and damage stability regulation. The package contained: 

  • a draft MSC resolution based on the Explanatory Notes for the new SOLAS chapter II-1 subdivision and damage stability amendments (i.e. applicable to ships built on or after 1 January 2020);
  • draft amendments to SOLAS regulation II-1/8-1.2 in order to improve the availability of a passenger ship's electrical power supply in cases of flooding from side raking damage, not only for "double-hull in way of main engine-room" but also for other scenarios.

Under this agenda item, SDC 4 also considered draft amendments to SOLAS regulation II-1/8-1.3 on computerized stability support for the masters of existing passenger ships in case of flooding. Though such guidance is relevant, there seem to be difficulties in applying a number of current guidelines to some existing passenger ships (MSC.1/Circ.1400 on guidelines on operational information for masters of passenger ships for safe return to port by own power or under tow; MSC.1/Circ.1532 on guidelines on operational information for masters of passenger ships for safe return to port; and MSC.1/Circ.1229 on guidelines for the approval of stability instruments). 

Therefore SDC 4 agreed to initiate the development of an appropriate set of new guidelines to clarify this matter. 


Jeppe Skovbakke Juhl
in Copenhagen, DK


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