How OCIMF MEG4 drives mooring operations forward

The fourth edition of OCIMF Mooring Equipment Guidelines (MEG4), issued in July 2018, has significantly changed the mentality of Managing Companies and seafarers’ approach on mooring issues.

It provides clear and concise guidance for ship and terminal designers, ship operators and mooring line manufacturers on safe mooring system design, with an emphasis on the safety of ship and terminal personnel.

The fourth edition has been extensively updated to address the following issues:

  • Lessons learned from incidents, most notably from failures of HMSF mooring lines;
  • Human centered mooring designs and human factors in mooring operations;
  • New and in-development regulations and guidance from the IMO on the safety of mooring;
  • Alternative mooring technologies and how they can be incorporated safely into the design of mooring systems both for ships and terminals.

Key updates

The Mooring Equipment Guidelines, fully reviewed and updated for the fourth edition, include the following new chapters and key changes:

  • Enhanced guidance for the purchasing, condition monitoring, and retirement of mooring lines and tails.
  • Enhanced guidance on documentation of mooring equipment.
  • Chapter on the Human Factors in Mooring Design.
  • Chapter on Jetty Design and Fittings.
  • Chapter on Ship Shore Interface.
  • Chapter on Alternative Technologies.

During the revision of MEG, it was clear that there has been confusion in the shipping industry with the term ‘Minimum Breaking Load’ (MBL) and other terminology related to line strength. Further, there was no industry guidance on condition-based monitoring of mooring lines and tails. Since nearly all mooring injuries are result of mooring line failures, OCIMF has strived to provide guidance and clarity on the condition-monitoring of mooring lines and there were several new terms introduced in MEG 4, as follows:

#1 Ship Design Minimum Breaking Load

The minimum breaking load of new, dry mooring lines for which a ship’s mooring system is designed, to meet OCIMF standard environmental criteria restraint requirements. The ship design MBL is the core parameter against which all the other components of a ship’s mooring system are sized and designed with defined tolerances. Nylon (polyamide) mooring lines should be specified as break tested wet because nylon lines change strength characteristics once exposed to water and generally do not fully dry to their original construction state.

#2 Line Design Break Force (LDBF)

LDBF is the minimum force that a new, dry, spliced mooring line will break at when tested. This is for all mooring line and tail materials except those manufactured from nylon which is tested wet and spliced. This value is declared by the manufacturer on each line’s mooring line certificate and is stated on a manufacturer’s line data sheet. When selecting lines, the LDBF of a line shall be 100-105% of the ship design MBL. The LDBF for nylon (polyamide) mooring lines should be specified as break tested wet because nylon lines change strength characteristics once exposed to water and generally do not fully dry to their original construction state.

#3 Working Load Limit (WLL)

The maximum load that a mooring line should be subjected to in operational service, calculated from the standard environmental criteria. The WLL is expressed as a percentage of ship design MBL and should be used as a limiting value in both ship design and operational mooring analyses. During operation, the WLL should not be exceeded. In the same way that SWL is a limit for fixed equipment, the WLL value is used as a limit with the standard environmental criteria and mooring layout when designing mooring systems in establishing mooring system designs. Steel wire ropes have a WLL of 55% of the ship design MBL and all other cordage (synthetic) have a WLL of 50% of the ship design MBL.

#4 Line Management Plan (LMP)

LMP is used to manage the operation and retirement of mooring lines and tails. The LMP also documents the requirements, assumptions and evaluation methods used in determining the line retirement criteria. The LMP is specific to an operator, ship type, and trade route; however, MEG4 gives general guidance on establishing a LMP.

#5 Mooring System Management Plan (MSMP)

The MSMP is to be ship specific and complement the ship’s safety management system. Through a ‘goal-based’ approach, core elements of the mooring system are identified against which high level ‘goals’ are established supported by more detailed ‘functional requirements’. A register of the mooring system components is maintained for the ship’s life in an accompanying Mooring System Management Plan Register (MSMPR).


How MEG4 aligns with ow HowIMO requirements

The new IMO Circ. 1175 rev.1 , Circ. 1619, Circ. 1620 has incorporated the terminology and practice of MEG-4. As such, following the above standards (applicable for ships constructed after 1-1-2024), operators will also comply with MEG-4 (Tankers, LPG, LNG and other applicable vessels). Additionally, as IMO new guidance requires a Mooring Management Plan to be implemented on board ships, operators may follow the guidance of MEG-4 when issuing such documents.

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