OCIMF guideline (2018) for mooring system design, operation, and inspection of tankers and gas carriers.
In practice
Operator's mooring-line management plan follows MEG4. Master uses the snap-back zone and line-design guidance during berthing.
Regulatory detail & full definition
OCIMF Mooring Equipment Guidelines 4 (2018) — industry guideline for the design, operation, and inspection of mooring systems on tankers and gas carriers. MEG4 introduces the concepts of Line Design Break Force (LDBF) and Ship Design Minimum Breaking Load (SDMBL), formalises the use of HMPE (Dyneema) fibre lines, and provides the snap-back zone marking scheme. The guideline also covers winch design, mooring point loading, fendering, and inspection regimes. SIRE 2.0 inspections check MEG4 compliance routinely, and many oil terminals require MEG4 conformance before berth approval.