The 11th meeting of the Ship Design and Construction Sub-Committee (SDC) of the International Maritime Organization (IMO) was held in London, UK, from 13 to 17 January 2025.

The session focused on the emergency Towing guidelines for non-liquid cargo ships, the further development of IP rules and their related guidelines, the Interim Explanatory note on the evaluation of system performance in the event of a fire or flooding incident on a passenger ship (MSC.1/Circ.1369) and the revision of the related circular, revisions 2011 The ESP rules to allow the use of RIT, amendments to the Guidelines for the Construction, Maintenance and Inspection/Inspection of Embarkation Facilities for the installation of safety nets for gangway and gangway ladders, amendments to SOLAS Chapter II-1 (Part C) and Chapter V and related non-mandatory documents relating to propulsion and steering systems for conventional and non-traditional ships, amendments to the International Convention on Load Lines 1988 Protocol railing setup, revision of relevant guidelines for the use of fiber reinforced materials in ship structures and experience accumulation stage for reducing underwater radiated noise of ships, etc.

The summary of the meeting is as follows:

First, formulate emergency towing guidelines for non-liquid cargo ships

By resolution MSC.549(108), the Maritime Security Council adopted an amendment to Articles 3-4 of Chapter II-1 of the SOLAS Convention, requiring non-liquid cargo ships of not less than 20,000 gross tons constructed on or after 1 January 2028 to be equipped with emergency towing devices. In line with this amendment, IMO has decided to develop new guidelines for emergency towing devices for non-liquid cargo ships. Based on the existing guidelines for emergency towing devices for liquid cargo ships and the results of the previous session, this session determined the working intensity standards for the main components of emergency towing (taking the ship's outfitting number as a parameter), added the provisions on the deployment time of towing devices, and finally finalized the draft of the Interim Guidelines for Emergency Towing of non-liquid cargo Ships.

The Meeting completed revised draft circulars MSC.1/Circ.1175/Rev.1 and MSC.1/Circ.1255. These drafts are to be submitted to MSC110 for approval.

Second, further formulate IP rules and related guidelines

Considering that there is still some ambiguity regarding the application of the International Code for the Safety of Ships Carrying Industrial Personnel (IP Code), MSC105 has agreed to carry out the work related to the second phase of the IP Code. In order to better reflect the characteristics of industrial personnel, this meeting completed the draft amendment to Article 1 of Part IV of the IP Rules, which clearly specifies that the weight of industrial personnel should also be 90kg/ person in the stability calculation, in accordance with the provisions of Article 2.2 of Part V of the rules. The draft amendments are to be submitted to the MSC110 meeting for approval.

Considering that the implementation time of IP rules is relatively short and the application experience gained by the industry is still insufficient, the Sub-Committee does not agree to carry out the formulation of IP rule-related guidelines at the current stage. In addition, in accordance with the latest IMO working methods, the Sub-Committee also agreed to consider that the work under this issue had been completed.

Revision of explanatory notes and relevant circulars related to the safe return of passenger ships to Hong Kong

The "safe return" requirement of the Convention has been in force for more than 10 years. As it is a target-type standard, there are some different understandings in the industry on the implementation of the safe return requirement, which need to be clarified or explained. In this regard, IMO has decided to initiate amendments to the relevant explanatory notes and related circulars. Building on previous meetings, the session finalized in principle the main body of the explanatory note to the MSC.1/Circ.1369 circular. Due to time constraints, the current session was not able to complete the discussion of the revised draft uniform interpretation in Appendix 1. The Subcommittee decided to continue to set up a post-meeting communications working group to continue the relevant work and to further consider amendments to other relevant circulars.

Amendments to the 2011 Rules for Enhanced Inspection Procedures during Inspections of International Bulk Carriers and Oil Tankers (2011 ESP Rules)

With the rapid development of information technology, the benefits of ship remote inspection technology (RIT) have been paid more and more attention by the industry. In order to allow the use of RIT for Close-up surveys, the meeting finalized the draft amendments to the 2011 ESP Regulations and the draft approval and certification guidelines for companies using RIT for hull structural inspections. The draft is to be submitted to MSC110 for approval and is expected to enter into force on January 1, 2028. The meeting also agreed to establish a communications working group to continue developing guidelines for testing the use of RIT.

Revision of the installation requirements for gangway and gangway ladder safety nets in the "Guide to Construction, Maintenance and Inspection/Inspection of Boarding and Disembarking Facilities"

The Guidelines for the Construction, Maintenance and Inspection/Inspection of Embarkation Facilities (MSC.1/Circ.1331) have been in operation for more than 10 years and the industry has accumulated some experience and application feedback. In order to mitigate the possible fall risk of safety nets installed by crew members, it was agreed at the previous session that safety nets may not be required for gangway or gangway ladders after side netting and railing protection, that new installations installed on or after 1 July 2026 should be constructed/tested in accordance with the new ISO standard, and that the test/inspection loads of relevant installations should be clarified and revised, There are also new maintenance requirements for crew protection and safety nets. The session completed the discussion of the remaining issues, defined the standards that should apply to newly installed embarkation facilities on and after 1 July 2026 for ships built before 1 January 2010, and finalized the draft amendments to the Guidelines. The draft is to be submitted to the MSC110 meeting for approval.

Revision of SOLAS Chapter II-1 (Part C) and Chapter V and related documents on ship steering and propulsion requirements to take into account conventional and non-traditional propulsion and steering systems

As new propulsion/steering systems (such as omnidirectional thrusters and pod-type thrusters) are not fully adapted to the current SOLAS Convention safety standards for ship steering and propulsion, IMO has decided to revise SOLAS Chapter II-1 (Part C) and Chapter V and related documents to take into account both conventional and non-traditional propulsion and steering systems.

Much of the discussion at this session focused on whether ship maneuverability requirements should be made mandatory, and there was considerable disagreement in the plenary. Finally, the Subcommittee agreed to include mandatory ship handling performance standards in the SOLAS Convention, while recognizing the need to further modify the proposed ship handling performance standards to address practical difficulties in implementing them. As a result, the Sub-Commission committee decided to extend the target time for the completion of the output and developed a road map to complete the development of mandatory ship maneuverability standards in SDC14 2028, subject to MSC approval, with a view to entering into force in 2032. Pending the submission of data and recommendations on mandatory ship handling performance standards, the Subcommittee did not see the need to re-establish the Communications Working Group at this stage.

Revision of Article 25 of the 1988 Protocol to the International Convention on Load Lines on the installation of railings

Considering that the gap between the two railings on the open deck is large, and the risk of personnel falling off the deck is greater, IMO decided to carry out the revision of the relevant convention. The current session discussed matters left over from the previous session, finalized the provisions for the substitution of chain lines for railings and finalized the draft amendment to article 25 of Annex B, Annex 1, to the 1988 Load Line Protocol. The draft amendment requires three levels of railings around all open decks and around all open inlets reached by crew members during a voyage. The draft amendments, which are to be submitted to MSC110 for approval, are intended to apply to ships with keels laid or similar stages of construction on or after 1 January 2028.

Guidelines for the use of FPR materials in ship structures

MSC 98 adopted the circular MSC.1/Circ.1574 "Interim Guidelines for the use of fibre-reinforced plastic (FRP) unit members in Ship structures: Fire safety issues", which stipulated that the guidelines should be reviewed four years after approval to make any necessary amendments based on experience gained. The guidelines currently apply only to FRP members that do not participate in the overall strength of a ship.

The report submitted by the Communications Working Group at the last session recommended that the scope of application of the MSC.1/Circ.1574 circular be extended from "FRP components that do not participate in the total strength of the ship" to "load separation" and "components that act on the overall strength", while preparing to improve the fire resistance test, smoke toxicity and carrying capacity of FRP materials. The recycling of FRP materials should be considered. Decides at this session:

(1) Establish a post-meeting communication working group to continue revising FRP guidelines and submit reports to SDC12.

(2) In addition to other aspects such as the recycling of FRP materials, the fire safety of load compartments and components should also be addressed within the scope of Chapter II-2 of the SOLAS Convention.

(3) Invite MSC110 to determine whether existing outputs include components that carry separation and act on the overall strength, such as clarifying whether this output is limited to Chapter II-2 of the SOLAS Convention or may go beyond that, and to make recommendations to the Communications Working Group established by SDC11 and to give instructions to SDC12.

9. Experience accumulation stage of reducing underwater radiated noise of ships

MEPC82 approved the Revised Underwater Noise Reduction Guidelines and EBP guidelines to reduce adverse impacts on Marine life. MEPC82 also decided that the topic would continue to be discussed in the SDC11 and SDC12 sub-committees on the technical aspects of the Experience Building Period (EBP) and the Underwater Radiated Noise (URN) action plan, and that there would also be a provisional agenda in MEPC 83-85 to discuss URN direction and policy issues.

The session discussed the development of a monitoring framework for URN EBP and further study of the scope and objectives of URN. The meeting decided to establish a communications working group to further discuss and take forward the relevant work, including reviewing the technical objectives of the URN Action Plan and developing next steps to advance these objectives; Develop a framework to assess progress made in the application of the revised URN guidelines, etc.

10. Others

Taking into account the fact that some IMO instruments referred to or referred to in the 2009 Alerts and Indicators Code are out of date, this session amended and updated accordingly, resulting in a new version of the 2025 draft Alerts and Indicators Code, which is to be submitted to the MSC110 and MEPC83 meetings for approval.

The session also agreed on a draft uniform interpretation of SOLAS Convention II-1/12.6.2 "Remote Control valves" to be submitted to MSC110 for approval.

The Meeting did not agree to the revised proposal of the MSC.1/Circ.1511/Rev.1 circular regarding the uniform interpretation of the lowest location of the protected annular escape path in the premises of category (A) machinery.