Safe mooring

Newbuildings – class and regulatory considerations

DNV Rules for ships reflect the statement in SOLAS Regulation II-1/3-8 that mooring and towing fittings and their attachments to the hull on any conventional ship built after 1. January 2007 must be of sufficient strength to withstand the maximum forces that they are likely to be subjected to in the ship’s normal service. 

The rules, as given in DNV-RU-SHIP Pt.3 Ch.11 Sec.2[5] apply to the design and construction of shipboard fittings and supporting structures. The rules in DNV-RU-SHIP Pt.3 Ch.11 Sec.1[3] state that minimum strength criteria (MBL_SD) be based on the ship’s equipment number (EN) and on the assumption that all mooring lines shown in the mooring arrangement plan are provided on board and are in use. The mooring lines are not a part of the classification scope. DNV Rules are compliant with IACS UR A2, which is used by all IACS members to verify compliance with SOLAS II-1/3-8, in particular MSC.1/Circ.1175.

Based on the towing and mooring arrangements plans, plan approval covers a review of the structural drawings, including the foundation above deck and fixation to deck inclusive the supporting structure below deck.

The selection of shipboard fittings may be made by the shipyard in accordance with a recognized industry standard (ISO, etc.).

Mooring equipment is not part of class scope for vessel covered by other rule sets like e.g RU-HSLC.

Example application of rule mooring forces on a fairlead

Categorization of mooring lines

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Revised SOLAS II-1/3-8

Revised SOLAS II-1/3-8 entering into force 1 January 2024 introduces guidelines concerning mooring equipment arrangement (MSC.1/Circ.1619) and maintenance (MSC.1/Circ.1620). Among other things, the selection and condition of mooring lines will become an integral part in design and maintenance process of mooring equipment. 

IACS unified interpretation (UI SC212) regulates and defines the scope of Class follow up on revised SOLAS II-1/3-8.