Safe mooring

Equipment number (EN) a dimensionless parameter used to determine the size and number of anchors, chain cables and mooring & towing lines for a new ship. However, it is important to remember that the anchoring equipment determined in accordance with the “Equipment Number” is intended for temporary mooring of a vessel within a harbour or sheltered area, when the vessel is awaiting berth, tide, etc.

For vessels approved by DNV, you will find the vessel EN on the vessel portal, under the tab “Classification”. 

If the EN is not listed here, it should be available on board in a document called “Equipment number calculation” or similar, or possibly as part of the towing and mooring arrangement plan documentation. 

If you cannot find the EN in on-board documentation or on the vessel portal, please contact our DATE service. The EN may have to be calculated (please see MSC.1/Circ.1175/Rev.1).

Reference is made to MSC.1/Circ.1175/Rev.1.: “The SWL, in tonnes, of each shipboard fitting should be marked (by weld bead or equivalent) on the fittings intended for mooring. For fittings intended to be used for both mooring and towing, TOW, in tonnes, according to 3.6, should be marked in addition to SWL.” For ships built before 2007, marking SWL on mooring fittings is not required by SOLAS II-1/3-8.  

You can use a keyword search with “Mooring” in the DNV Approval finder, for instance. Here you have different filter options and a search field where you can enter keywords.

The rules can be found in our Rules for classification: Ships (RU-SHIP), Part 3"Hull",chapter 11 "Hull equipment, supporting structure and appendages" (document code: DNVGL-RU-SHIP Pt.3 Ch.11).

Mooring equipment is only scope of class for ships covered by RU-SHIP. There are no requirements, but it's advised to consider the criteria in RU-Ship.

You will find all the information in IMO-Vega (subscription required) or in the following circulars in IMODOCS (Public Account required):

MSC.1/Circ.1175/Rev.1 – revised “Guidance on shipboard towing and mooring equipment”

MSC.1/Circ.1619 – “Guidelines on the design of mooring arrangements and the selection of appropriate mooring equipment and fittings for safe mooring”

MSC.1/Circ.1620 – “Guidelines for inspection and maintenance of mooring equipment including lines”

The above guidelines are a result of the amended SOLAS Regulation II-1/3-8, which will enter into force on 1 January 2024.

IACS unified interpretation (UI SC212) of requirements for mooring arrangement and equipment in SOLAS regulation II-1/3-8, link: IACS PARTICIPATION AT SDC 9 - IACS.

Please see the Oil Companies International Marine Forum (OCIMF) website.

There are local requirements around the world, both related to ports and canals. Below are links to information regarding some local requirements. It is recommended that you always check with local agents/authorities whether any local requirements exist. 

Panama Canal transit, old and new locks: OP NOTICE N01 – 2021: Dec 2020 (pdf)

New requirements for Capesize vessel deck fittings: Pilbara Ports Authority (PPA) PORT OF PORT HEDLAND LOCAL MARINE NOTICE 01/2018 (P): Local-Marine-Notice-PH-02-21-(P)-New-requirements-for-Capesize-vessels-deck-fittings-and-attachment-1.pdf (pilbaraports.com.au) (pdf)

In general, this guideline applies to all existing vessels. It should however be noted that the verified SWL of the mooring equipment and fittings may not be readily available for vessels built prior to 1 January 2007. For vessels built on or after 1 January 2007, the SWL and necessary calculations should be available (ref. SOLAS Regulation II-1/3-8 adopted on 13 May 2005 and in force since 1 January 2007).

For ships built before 2007, marking SWL on mooring fittings is not required by SOLAS II-1/3-8.

DNV may offer a voluntary Statement of Compliance for vessels classed with DNV. In general, this will include a review of documentation and the checking of the mooring equipment marking. See the Services tab for further information. Alternatively, voluntary class notation “Mooring” can be offered.

DNV customers will find links to order a voluntary statement of compliance and information, in the Compliance Planner (Learn more) available in Fleet status via the Veracity data platform (Sign in).