Stability guidance and load lines
UK and international codes and standards for vessel stability and loadlines, safety advice and regulations for boatmasters, designers or shipbuilders dealing with vessel stability.
Introduction
This guide covers the UK and international codes and standards for vessel stability and loadlines, stability approval, stability information books, and stability guidance - grouped according to vessel type.
It is aimed at boatmasters assessing vessel stability, vessel designers and shipbuilders. The guide also includes advice on maintaining safety on board your vessel, guidance for surveyors, and how you can comply with the regulations.
Load lines, marks and load line certificates
Ship stability is underpinned by the UK’s load line regime, which imposes requirements on certain ships to meet stability criteria. Ships conforming with the load line requirements are issued with certificates, and no ship to which the load line requirements applies may proceed to sea without a valid certificate.
Load line certificates are issued by MCA surveyors. However, vessel owners and masters should be involved with the periodical inspection of vessels. Find guidance on load line certificates for surveyors.
Load line regulations
The Merchant Shipping (Load Line) Regulations 1998 are the UK’s legislation on loadline. Find the Merchant Shipping (Load Line) Regulations 1998.
The Merchant Shipping (Load Line) (Amendment) Regulations 2000 amends the load line requirements for different types of vessels, operating in varying seasonal zones and periods. Read MSN 1752 Amended Merchant Shipping (Load Line) Regulations 1998
Read The Merchant Shipping (Load Line) (Amendment) Regulations 2000
Read The Merchant Shipping (International Load Line Convention) (Amendment) Regulations 2018
How to record freeboard information in log books
Masters of Ro-Ro passenger vessels must record data on freeboard, stability and recording of draughts in their official log books.
Access of water through spurling pipes
Specific guidance has been issued to vessel masters to ensure that excess water cannot access the vessel through the spurling pipes - apertures allowing anchor chains to enter chain lockers through the forecastle deck. Read MSN 622 Miscellaneous openings: spurling pipes
Specific freeboard and stability guidance according to vessel type
Guidance for marine surveyors assessing passenger vessel construction has been produced by the MCA. Read the Merchant Shipping (Ro-Ro Passenger Ships) (Stability) Regulations 2004.
Ro-Ro passenger vessels
Ro-Ro passenger vessels must meet the survivability requirements - eg time required for the evacuation of everyone on board - agreed as part of the 1995 amendments to the SOLAS convention (the ‘Stockholm Agreement’). Read the Merchant Shipping (Ro-Ro Passenger Ships) (Stability) Regulations 2004.
The MCA document MSN 1790 (M) explains how EU Directive 2003/25/EC has been incorporated into UK law, in the form of the Merchant Shipping (Ro-Ro Passenger Ships) (Stability) Regulations 2004.Read MSN 1790 Stability requirements for ro-ro passenger ships
There are specific stability requirements for Ro-Ro passenger ships. Read the Merchant Shipping (Ro-Ro Passenger Ships) (Stability) Regulations 2004.
The MCA has published dynamic stability modelling guidance for designers of high-speed craft. Read MGN 327(M) High speed craft dynamic stability research
Bulk Carriers
Bulk carriers of 150 metres’ length and above, carrying high-density dry bulk cargoes, must meet additional safety measures. Read MGN 668 (M) Amendment 1: Additional safety measures for bulk carriers
The hardware and software of hull stress monitoring systems must be approved by the MCA or by a nominated body, such as a classification society. Read MGN 108 (M) Hull stress monitoring systems
Precautions against flooding of forward compartments - particularly for bulk carriers - are set out in the MCA document MGN 210 (M). Read MGN 210 (M)
Cargo vessels of 80 metres and over
MSN 1715 (M) outlines damage stability requirements for cargo vessels of 80 metres and above, aimed at shipbuilders, marine architects and masters. Read 1715 part 1.doc
Stability approval by classification societies
The MCA has agreements with Classification Societies so that they may carry out surveys of vessel stability as part of the safety certification process. For more information, see the guide on how to prepare and apply for a vessel survey.
Before construction of a vessel begins, the owner must submit structural plans of the hull, subdivisions, bulkheads and construction materials to the relevant society. Read Stability guidance and load lines
Owners of certain vessels must also submit stability calculations to classification societies to prove the vessel meets the damage stability requirements outlined in the MCA’s MSN 1698 (M). Read MSN 1698 (M) The Merchant Shipping (Passenger Ship Construction: Ships of Classes I, II and II(A) Regulations 1998 - SI 1998/2514)
Stability guidance for masters and watchkeepers
Masters and watchkeepers of sailing and powered vessels can get advice on maintaining vessel stability at sea from several maritime organisations.
Further information on stability guidance and load lines
The MCA is the agency responsible for implementing the government’s maritime safety policy. Its seafarer health and safety branch can provide safety information for owners and operators of passenger vessels. Find information on the Maritime and Coastguard Agency
Find further information on fishing vessel stability
Chamber of Shipping
The Chamber of Shipping is the trade association for the UK shipping industry. You can call the Chamber of Shipping Enquiry Line on 020 7417 2800. Read about the Chamber of Shipping’s services on the Chamber of Shipping website
International Maritime Organization (IMO)
The IMO is a UN agency overseeing international standards to regulate shipping. You can contact the IMO Helpline on I020 7735 7611. Read about the IMO’s role in the international regulation of shipping on the IMO website
Royal National Lifeboat Institution (RNLI)
The RNLI provides a 24-hour lifeboat search and rescue service around the UK coasts, and also publishes information on sea and beach safety. Find sea safety information on the RNLI website.
Royal Institution of Naval Architects (RINA)
The RINA is a membership association for professionals at all levels in design, construction, maintenance and operation of marine vessels and structures. Find out about the work of the RINA on the RINA website.
Further information
MCA Marine Technology Branch
023 8032 9100
Stability guidance booklet for masters and watchkeepers for powered vessels
The Merchant Shipping (Load Line) (Amendment) Regulations 1998 information
The Merchant Shipping (Load Line) (Amendment) Regulations 2000 guidance
MSN 1752 Amended Merchant Shipping (Load Line) Regulations 1998
Updates to this page
Last updated 20 September 2023 + show all updates
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Removed out of date information and updated links.
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First published.