The fourth edition of OCIMF’s Mooring Equipment Guidelines (MEG4) provides recommendations for mooring system design, selection, maintenance, and retirement. The information below is designed to bring clarity and expand on Samson's approach to certification and product performance validation. Beyond product certification, Samson has helped over 100 vessels transition to the new guidance. 

Samson has a long, rich history in the maritime industry. Backed by over 140 years of innovation we've got more experience with HMPE than any of our competitors. Watch the video to learn more.



MEG4 Compliance Image

MEG4 Compliance 
Customer Information

Learn More
LNG Article Image

LNG Industry Article: The
Changing Mooring Environment

Learn More

and LDBF

Learn More

MEG4 Overview


ICARIA® Service Program Overview


Frequently Asked Questions

How do I prepare for a MEG4 SIRE inspection?

A vessel can prepare for a MEG4 SIRE inspection through development of a robust Mooring System Management Plan (MSMP), documented adherence to the vessel or fleet specific Line Management Plan (LMP), and procurement of lines that follow the specification process lined out in MEG4 guidance. Review of Chapter 9 of the OCIMF Vessel Inspection Questionnaire (VIQ), latest edition available at, should be performed during development of a vessel MSMP and LMP.

How do we adapt LDBF for existing ships (pre-MEG4)?

Ships built to MEG4 will already have a ship design MBL to satisfy OCIMF Standard Environmental Criteria restraint requirements and each mooring line will have a LDBF. Mooring fittings and mooring winch brake rendering values are based on the ship design MBL.

Ships built prior to MEG4 should still follow the same principles when defining their mooring winch brake render setting. For these vessels the terminology referenced will differ, “Design Rope MBL” in MEG3 for example (See Figure 7,3 in MEG3), but should be a synonymous specification with the ship design MBL as defined in MEG4.

How do I use the performance indicators?

The MEG4 performance indicators should be used during the procurement cycle to help purchasers and operators make more accurate comparison of rope products (mainlines and tails). For more details see our MEG4 Compliance Customer Information packet (in Resources).

What if my LDBF is lower than my hardware ratings? 

If the vessel was designed based on MEG3 guidelines (or prior), operators should document whether the intended LDBF is below/above MBLsd as an exception in their MSMP/LMP and define a timeline in that plan to transition to larger / smaller LDBF ropes as appropriate.  As referenced in the book’s introduction (Page V), this transition should be based on a comprehensive assessment and past performance data can and should be used to justify existing ropes on board the vessel and determine appropriate plans for changing over to new sizes or products. For more information, refer to the MEG4 Introduction Page V.

Do I need MEG4 certificates for secondary lines?

MEG4 does not explicitly mandate certification for secondary lines however as mentioned, if secondary lines are in use that have not been fully tested and endorsed, Samson may be able to provide MEG4 certificates upon request. Contact your Samson rep.

Why have the linear density values changed?

In general, linear density measurements are taken by loading a sample length of rope to a “reference” tension level (based on nominal rope diameter), adding two marks that are distanced at a specified length, cutting the rope at those marks, and then weighing the cut sample. Using these length and weight measurements, linear density can be calculated for that rope product and size. 
An additional length measurement can be taken prior to weighing the cut sample. Synthetic ropes tend to shorten when relaxed and thus a “relaxed” length measurement can be taken. Samson has traditionally used this relaxed length measurement in linear density calculations. In MEG4, this property is dictated to base the calculation off the tensioned length measurement. To conform to the industry movement for standardization of performance indicators, customers may notice a slight reduction of the linear densities per rope diameter on Samson products.

When we are changing part of mooring system, (e.g. mooring tails) what reference values should be taken as reference to calculate 125–130%?

The governing value to compare any line or hardware specifications to is the vessel specific MBLsd. In the case of mooring tails for example, the specification for TDBF of tails utilized should fall within the corresponding range of 125–130% of the vessel MBLsd.

How are other operators responding to terminal and SIRE queries, if vessel goes ahead with MEG3 recommendation for mooring system?

For existing ships that have designed their systems and operations based on MEG3 guidelines, any deviations from guidance provided in MEG4 should:

  • be documented in a vessel MSMP that is available on the ship throughout its life
  • identify a timeline and measures needed to follow the recommendations of MEG4
  • detail interim measures taken to address the recommendations of MEG4,with reasons given for why the changes have not been implemented yet

Do I need a break test and third-party witnessing every time I purchase a rope?

No. The intention behind the base design review process and 3rd party endorsement is to reduce the necessity of having single break testing requirements at time of order. Use of consistent test methods and defined statistical evaluation approaches outlined in MEG4 aims to ensure rope suppliers provide consistent specifications to make any additional testing requests at time of procurement unnecessarily redundant.

More Questions?

Or contact us directly at


Consider Samson your partner in the field and on the water. In addition to our new integrated technology and service solution, ICARIA, we also provide a number of valuable resources to help ensure your operation’s success.