Yacht classification definitions

21 January 2015 • Written by Paolo Moretti, RINA
The yachting industry is still adapting to regulations and conventions which apply to private and commercial vessels alike.

The merchant shipping sector is ruled by safety regulations developed since the beginning of the 20th century, and is familiar with international conventions such as SOLAS, MARPOL and Load Lines. But the application of common safety requirements to pleasure vessels is something relatively new – a continuous work in progress – and is very much dependant on the service and the flag of the yacht.

Defining the problems

Definitions do not help. How often have we read of large yachts, superyachts, megayachts, gigayachts or other bombastic adjectives? How many times have we mentioned MCA, RINA, and Lloyd’s, without having a clear idea of who’s doing what?

A good starting point for understanding the subject is to clarify the main definitions and the roles of the main players:

Large yacht

A large yacht is a pleasure vessel with a load line length equal to or over 24m. Almost all the flag administrations have adopted safety codes dedicated to large yachts and this is, therefore, the only definition having a universal meaning in the international regulatory framework of yachts.

Commercial yacht

A motor or sailing vessel in commercial use (i.e. charter) for sport and pleasure, carrying no cargo and not more than 12 passengers.

Private yacht

A pleasure vessel solely used for the recreational and leisure purpose of its owner and his guests.

Flag administration

The government of the state whose flag the yacht is entitled to fly. This administration sets the safety regulations, manning requirements and fiscal aspects relevant to the yacht registration.

Different flag administrations can inspect the safety aspects of yachts with their own inspectors (see MCA for example) or delegate this activity partially or totally to other recognised bodies such as the classification societies.

The main flag authorities in the yachting industry are: The UK-MCA, Cayman Islands, Isle of Man, Malta, the Marshall Islands, Italy and Luxembourg.

Classification societies

Organisations that establish and apply technical standards in relation to the design, construction and survey of ships.

Classification rules are developed to assess the structural strength and integrity of the essential parts of the hull, the reliability and function of the propulsion, steering systems, power generation and all the other features installed on board which contribute to guarantee the main essential services.

In addition to this ‘third party check’ function, class societies carry out statutory duties on behalf of the major flag administrations in accordance with specific delegation agreements signed with each government.

The main class societies involved in yachting are: American Bureau of Shipping, Bureau Veritas, Det Norske Veritas, Germanischer Lloyd, Lloyd’s Register, and RINA.

Maintaining a yacht in class requires regular surveys by qualified engineers and surveyors.

Large yachts: Applicable rules and certificates

Private yachts

The mandatory requirements for these boats are very light. For the majority of flag states, a registration survey and a tonnage measurement, carried out by an authorised surveyor, are sufficient.

The only mandatory international conventions are those relevant to the marine environment: MARPOL and the Anti-Fouling System Convention.

The International Convention for the Prevention of Pollution from Ships (MARPOL) is intended to eliminate the intentional pollution and to minimise the accidental pollution of the marine environment caused by harmful substances.

The Anti-Fouling System Convention’s purpose is to eliminate the presence of harmful substances for the marine environment contained in anti-fouling paints applied to ships.


While classification is not mandatory, building and maintaining a private yacht in class is the only evidence that the boat has been designed, constructed and operated in compliance with appropriate technical standards. It is therefore highly desirable, especially in relation to insurance and re-sale purposes.

Commercial yachts

All flag administrations require commercial yachts to be certified in accordance with a specific large yacht safety code.

The most popular of these safety codes, and the first that was developed, is the MCA Large Commercial Yacht Code (LY2) published in 2004. It replaced the Code of Practice for the Safety of Large Commercial Sailing and Motor Vessels (LY1) published in 1997.

LY2 is applied by the Red Ensign Group Flags (UK, Cayman Islands, Isle of Man, Bermuda, Gibraltar, British Virgin Islands, etc.) and is recognised as a reference standard for all the yachting industry.

Other flags have developed similar codes. Luxembourg, Italy, Marshall Islands, Malta, Belize and The Netherlands are some examples.

While introducing a stricter set of rules and regulations compared to private yachts, commercial registration offers yacht owners the possibility of making a profit from the chartering activity of their boats, and allows them to take advantage of all the other benefits of a commercial operation (in particular VAT exemption on the purchase, sale, bunkering, provisions, dry-docking, and others).

Mandatory certificates

The number and type of the mandatory certificates depends on the size of the vessel; the following is an indicative list:

  • International Tonnage Certificate : A measurement of the internal volumes of the yacht expressed in gross tons (GT). This measurement should not be confused with displacement tonnage, which quantifies the weight of a vessel.
  • Large Yacht Code Certificate : Covers life-saving appliances, fire protection and means of escape, navigational and signalling equipment, intact and damaged stability, manning and crew accommodation.
  • Class Certificate : This mainly deals with the yacht’s hull, machinery, electrical equipment and outfitting.
  • International Load Line Certificate : This certifies the weather-tightness of the yacht.
  • Safety Radio Certificate : This is applicable if gross tonnage exceeds 300GT This concerns the radio communication and distress installations.
  • MARPOL Annex I Certificate : This is applicable if gross tonnage exceeds 400GT This deals with the disposal of oil and bilge water from machinery spaces.
  • MARPOL Annex IV Certificate : This is applicable if gross tonnage exceeds 400 or the yacht is certified to carry over 15 persons. This deals with the disposal of sewage from ships.
  • MARPOL Annex V : This is applicable to all ships. It covers the disposal of rubbish.
  • MARPOL Annex VI : This is applicable if gross tonnage exceeds 400GT as well as to all main and auxiliary engines with a power exceeding 130kW. It concerns the emissions from main and auxiliary engines (NOx and SOx).
  • Safety Construction and Safety Equipment : These are additional prescriptions on machinery, electrical parts, life-saving and navigational equipment for yachts with a gross tonnage above 500GT.
  • International Safety Management Certificate : This is only applicable to yachts having a gross tonnage greater than 500GT. A certified management company is requested to carry out this service, preparing operational manuals, procedures for drills, and taking care of the maintenance of the yacht and its installations.
  • International Ship and Port Security Certificate : This is only applicable to yachts having a gross tonnage greater than 500GT and deals with the anti-piracy certification. A certified management company is requested to provide the ashore assistance and establish on-board procedures and operational manuals.
The regulations that govern sea-going vessels are complex, and require expert advice to ensure compliance.

The GT Factor

The gross tonnage value (GT) is a key issue, not only as a reference for the registration fees applied by the different flag administrations, but also because it determines whether an international convention, rather than a particular safety standard, applies to a yacht.

The table below summarises how the conventions and relevant certificates come into force depending on the gross tonnage of the yacht. In particular, the following values may have a critical impact:

300GT: In many codes, when you reach this value the yacht must be certified in unrestricted service (stricter requirements regarding stability, load line and life-saving appliances).

400GT: This is the threshold for almost all the environmental conventions such as MARPOL and Anti-fouling System.

500GT: This is the threshold for the application of the SOLAS Convention, meaning stricter requirements on machinery, safety systems, materials of construction, fire protection, life-saving appliances and navigational equipment. Furthermore an external certified management company is requested for the ISM and ISPS certifications.

The tonnage issue could also arise on existing yachts when undertaking major refits or modifications, in that any change to the internal volumes of the boat – such as adding enclosed deckhouses or superstructures, or modifying the hull transom or bow – will modify the tonnage value with the risk of subjecting the yacht to stricter mandatory rules.

UPDATE: Since this article was originally published, LY2 has been superseded by Large Commercial Yacht Code Revision 3 (LY3).

Tom Isitt

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