OCIMF Mooring Equipment Guidelines (MEG4)

The new fourth edition mooring equipment guidelines (MEG4) was issued in July 2018 by the Oil Companies International Marine Forum (OCIMF). Maybe you have not implemented MEG4 yet and it will be relevant for your company!

These new OCIMF guidelines are a new test methods and rope management recommendations to changes in the design of the terminals and ships use of mooring lines. Which has resulted in a reduction of serious incidents on board terminals and ships.

NOS A/S provides technical ropes expertise and MEG4 certified ropes, following the recommendations from the fourth edition of the OCIMF Mooring Equipment Guidelines.

OCIMF update to MEG4

The new mooring equipment guidelines focuses on the safety of terminal and ship personnel. MEG4 supersedes MEG3. It is primarily the chemical industry sectors, gas carriers, conventional tankers and terminals which can benefit from this update.

This 4th edition has been updated with new chapters and key changes which include:

  • Enhanced guidance for purchasing, condition monitoring, and retirement of mooring lines and tails.
  • Enhanced guidance on documentation of mooring equipment.
  • New chapter around ship-shore interface.
  • New chapter around jetty design and fittings.
  • New chapter around alternative technologies.
  • New chapter around human factors in mooring design.
  • The Mooring System Management Plan (MSMP).
  • Line Management Plan (LMP).
meg4 mooring line working range

Ship Design Minimum Breaking Load

The minimum breaking load of new dry mooring lines, for ships are 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.


Line Design Break Force (LDBF)

LDBF is the minimum force that a new dry spliced mooring line will break at when tested according to appendix B. This is for all mooring line and tail materials except those manufactured from nylon which is tested wet and spliced. The values are declared by the manufacturer on each line’s mooring line certificate. See after appendix B on the manufacturer’s line data sheet. As outlined in appendix B, 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.


Working Load Limit (WLL)

The maximum load of 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.


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.


Mooring System Management Plan (MSMP)

MSMP will complement the ship’s safety management system. Which through a goal-based approach, core elements of the mooring system are identified, 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).

MEG4 Mooring principles

This video shows the core principles of MEG4, including the standard environmental criteria, the ship design Minimum Breaking Load (MBL) and the principle of aligning design and construction of all elements of the mooring system from the outset.