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.
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 on the MCA website.
Load line regulations
The Merchant Shipping (Load Line) Regulations 1998 are the UK’s legislation on loadline. Find the Merchant Shipping (Load Line) (Amendment) Regulations 1998 on the Legislation.gov website.
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 (M) The Merchant Shipping (Load Line) Regulations 1998, as amended by the Merchant Shipping (Load Line) (Amendment) Regulations 2000 on the MCA website.
Download MSN 1752 (M) The Merchant Shipping (Load Line) Regulations 1998, as amended by the Merchant Shipping (Load Line) (Amendment) Regulations 2000 - Corrected page 10 from the MCA website (PDF, 66KB).
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. Download MSN M.1391 Official log books recording draughts, freeboard and stability required for Ro-Ro passenger ships from the MCA website (PDF, 9KB).
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. Download MSN 622 Miscellaneous openings in freeboard and superstructure decks - spurling pipes from the MCA website (PDF, 54KB).
Specific freeboard and stability guidance according to vessel type
Guidance for marine surveyors assessing passenger vessel construction has been produced by the MCA. Find out about passenger vessel construction standards used by surveyors on the MCA website
Regulations for the operational control of passenger vessel watertight doors are listed in MSN 1151. Download MSN 1151 (M+F) The operational control of watertight doors in passenger ships from the MCA website (PDF, 10KB).
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’). Download Ro-Ro passenger vessel survivability recommendations from the MCA website (PDF, 16KB).
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. Download MSN 1790 (M) Agreement Concerning Specific Stability Requirements for Ro-Ro Passenger Ships Undertaking Regular Scheduled International or Domestic Voyages between European Ports from the MCA website (PDF, 2.14MB).
There are specific stability requirements for Ro-Ro passenger ships. Read the Merchant Shipping (Ro-Ro Passenger Ships) (Stability) Regulations 2004 on the Legislation.gov website.
A later EU directive - 2005/12/EC - makes several changes to the Ro-Ro vessel stability assessment regulations of MSN 1790 (M). These include new stability tests, and a new model test method. Read the Agreement Concerning Specific Stability Requirements for Ro-Ro Passenger Ships Undertaking Regular Scheduled International or Domestic Voyages - Amendment No.1 on the MCA website.
A method of calculating Ro-Ro passenger vessel survivability was agreed as part of SOLAS 90. Download Ro-Ro vessel calculation of survivability standards guidance from the MCA website (PDF, 11KB).
The MCA has published dynamic stability modelling guidance for designers of high-speed craft. Download Marine Guidance Note (MGN) 327 (M) Research Project 502: High-Speed Craft Dynamic Stability in Following and Quartering Seas - Design Guidance from the MCA website (PDF, 262KB).
Bulk carriers of 150 metres’ length and above, carrying high-density dry bulk cargoes, must meet additional safety measures. Download MGN 144 (M) The Merchant Shipping (Additional Safety Measures for Bulk Carriers) Regulations 1999 (SI 1999/1644) from the MCA website (PDF, 178KB).
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. Download MGN 108 (M) Hull Stress Monitoring Systems from the MCA website (PDF, 144KB).
Precautions against flooding of forward compartments - particularly for bulk carriers - are set out in the MCA document MGN 210 (M). Download MGN 210 (M) Advice on the dangers of flooding of forward compartments from the MCA website (PDF, 91KB).
Other safety measures for bulk carriers are set out in the Merchant Shipping (Additional Safety Measures for Bulk Carriers) Regulations 1999. Find out about the Merchant Shipping (Additional Safety Measures for Bulk Carriers) Regulations 1999 on the Legislation.gov website.
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. Download MSN 1715 (M) Subdivision and Damage Stability of Cargo Ships of 80m in Length and Over Part 1 from the MCA website (PDF, 682KB).
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. Download guidance on vessel construction details that must be submitted to classification society surveyors from the MCA website (PDF, 24KB).
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). Download MSN 1698 (M) The Merchant Shipping (Passenger Ship Construction: Ships of Classes I, II and II (A)) Regulations 1998 from the MCA website (PDF, 730KB).
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 contact details for the MCA vessel policy department on the MCA website.
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.
MCA Marine Technology Branch
023 8032 9100
Download MSN 1790 (M) Agreement Concerning Specific Stability Requirements for Ro-Ro Passenger Ships Undertaking Regular Scheduled International or Domestic Voyages between European Ports from the MCA website (PDF, 2.14MB)