Chapter 4 - Construction and Strength
Clasification Society 2024 - Version 9.40
Statutory Documents - MCA Publications - Yacht Code - January 2019 Edition - Part A - Large Yacht Code (up to 12 passengers) - Chapter 4 - Construction and Strength

Chapter 4 - Construction and Strength

Objective: The purpose of this Chapter is to ensure that all vessels are constructed to a consistent standard in respect of strength and watertight integrity. New Vessels shall be built to the requirements of a Recognised Organisation and issued with a commercial Certificate of Classification. Existing Vessels which do not have a Certificate of Classification issued by a Recognised Organisation shall obtain such a certificate. For vessels under 500GT alternative arrangements for Short Range operation may be agreed by the Administration. The extent of the watertight bulkheads defined in Section 4.3 is to ensure that sufficient buoyancy is maintained by the vessel to meet the damaged stability requirements of Chapter 11.

4.1 General Requirements

(1) All vessels shall have a freeboard deck.

(2) All vessels shall be fitted with a weather deck throughout the length of the vessel and be of adequate strength to withstand the sea and weather conditions likely to be encountered in the declared area(s) of operation.

(3) The declared area(s) of operation and any other conditions which restrict the use of the vessel at sea shall be recorded on the load line certificate issued to the vessel.

(4) The choice of hull construction material affects fire protection requirements, for which reference shall be made to Chapter 14A and 14B.

(5) Where a considerable risk of lightning strike is identified vessels shall have lightning strike protection.

(6) Where there are no Recognised Organisation requirements for the fitting of double bottoms, SOLAS II-1/9 shall be applied to vessels of over 80m Length.

4.2 Structural Strength

(1) All vessels shall be constructed in accordance with the requirements of a Recognised Organisation.

(2) Attention shall be paid to local or global hull strength requirements for the provision of ballast.

4.3 Watertight Bulkheads

(1) Chapter 11 of the Code deals with subdivision and damage stability requirements which shall determine the number and positioning of watertight bulkheads defined below.

(2) Watertight bulkheads shall be fitted in accordance with the following requirements:

  • (a) The strength of watertight bulkheads and their penetrations, and watertight integrity of the division shall be in accordance with the requirements of a Recognised Organisation

  • (b) Generally, openings in watertight bulkheads shall comply with the standards required for passenger vessels, as defined in SOLAS II-1. Hand operation from above the bulkhead deck and a hydraulic accumulator may be omitted if each door has its own individual power-pack electrically driven via the emergency switchboard, and control voltage from emergency battery, and each door can be operated manually at the door. Edge strips which stop the door closing on contact are not permitted.

  • (c) Watertight Doors may be located outboard of the B/5 Line. However, where powered watertight doors are provided, the main control system shall in all cases be located inboard of the B/5 line in order to ensure the continued operation of undamaged doors.

  • (d) Approved hinged doors may be provided for infrequently used openings in watertight compartments, where a crew member shall be in immediate attendance when the door is open at sea. Audible and visual alarms shall be provided in the wheelhouse.

  • (e) Unless otherwise required by section 4.4, watertight doors in yachts under 500GT may be approved hinged doors provided that there is an audible and visual alarm on the Bridge indicating when the door is open. The doors shall be kept closed at sea and marked accordingly. A time delay for the alarm is acceptable.

  • (f) Procedures for the operation of watertight doors shall be posted in suitable locations. Watertight doors shall be normally closed, with the exception of sliding watertight doors providing the normal access to frequently used living and working spaces. Additionally when an access is unlikely to be used for lengthy periods, the door shall be closed. Operational tests of watertight doors, shall take place weekly. For Yachts in which the voyage exceeds one week in duration, a complete set of operational tests shall be held before the voyage commences, and others thereafter at least once a week during the voyage.

4.4 Enclosed Compartments Within the Hull and Below the Bulkhead Deck Provided with Access Through Openings in the Hull

(1) Compartment(s) below the bulkhead deck, provided for recreational purposes, oil fuelling/fresh water reception or other purposes to do with the business of the vessel and having access openings in the hull, shall be bounded by watertight divisions without any opening (i.e. doors, manholes, ventilation ducts or any other opening) separating the compartment(s) from any other compartment below the bulkhead deck, unless provided with sliding watertight doors complying with 4.3(2), or for vessels under 500GT, hinged doors complying with 4.4(2).

(2) For vessels under 500GT, openings from any other compartment below the bulkhead deck may be fitted with hinged watertight doors provided:

  • (a) after flooding through the shell opening of the space containing the shell opening, the resultant waterline is below the sills of the internal openings in that space; or

  • (b) bilge alarms are fitted in the compartment containing the shell opening, with a visual and audible warning both on the bridge and locally; and

  • (c) any hinged door opens into the compartment containing the shell opening; and

  • (d) "open" door alarms, both visual and audible fitted on the bridge; and

  • (e) the door shall be fitted with a single closing mechanism; and

  • (f) where the sill height of the internal door is not higher above the deepest loaded waterline than the sill height of the shell opening, then 4.4(4)(b) and 4.4(4)(c) shall also be considered to the satisfaction of the Administration.

(3) Openings in the hull shall comply with SOLAS II-1/15-1 - External openings in cargo ships. Provision shall be made to ensure that doors may be manually closed and locked in the event of power or hydraulic failure. Openings are generally to be fitted with a sill not less than 600 millimetres above the Design Waterline. Means shall be provided to prevent the unauthorised use of the doors locally through provision of secondary or remote control, through an interlock, dual control process or procedure.

(4) Openings in the hull with a sill height less than 600 millimetres above the Design Waterline may be specially considered by the Administration. This consideration shall include but is not limited to:

  • (a) doors from the space providing internal access are to have a sill height at least 600 millimetres above the Design Waterline;

  • (b) the effect of flooding on stability is considered;

  • (c) operational controls and limitations on when and where opening may be used.

(5) Protection of safety critical systems such as those for securing of the hull opening closed and any provided in accordance with Chapter 14, shall have a liquid ingress protection of level 5 (e.g. IP 65) in accordance with the International Protection (IP) Marking, IEC Standard 60529 or equivalent.

4.5 Rigging on Sailing Vessels

(1) General

  • (a) The condition of the rig shall be monitored in accordance with a Maintenance Manual and a planned maintenance schedule. The schedule shall include, in particular, regular monitoring of all the gear associated with safe work aloft and on the bowsprit (see 22.3).

(2) Masts and Spars and Standing Rigging

  • (a) Dimensions and construction materials of masts and spars and dimensions of standing rigging including connection to chain plates shall be in accordance with the requirements or recommendations of a Recognised Organisation or a recognised national or international standard.

  • (b) The associated structure for masts and spars (including chainplates, fittings, decks and floors) shall be constructed to effectively carry and transmit the forces involved.

  • (c) Compliance with (a) and (b) shall be confirmed by a design review and approval by a Recognised Organisation (e.g. Rig Design Certificate) which is assigned with the review of the rig.

  • (d) The Maintenance Manual provided by the mast manufacturer shall be reviewed and approved by the Recognised Organisation which is assigned to review the rig design.

  • (e) A physical survey on the rig stepping procedure and the rig behavior during sea trials is to be carried out by or on behalf of the Recognised Organisation that is involved with the classification of the vessel’s hull.

  • (f) Annual surveys on the vessel shall include reviewing records and history of rig maintenance measures against the specifications provided by the maintenance manual.

(3) Rigging Fittings

  • (a) The strength of all blocks, shackles, rigging screws, cleats and associated fittings and attachment points shall exceed the breaking strain of the associated running or standing rigging.

(4) Sails

  • (a) Adequate means of reefing or shortening sail shall be provided.

  • (b) Sailing vessels operating as Short Range Yachts need not carry storm canvas.

  • (c) All other vessels shall either be provided with separate storm sails or have specific sails designated and constructed to act as storm canvas.

4.6 Asbestos Containing Materials

  • (1) Any installation of materials that contain asbestos shall be prohibited, for all yachts without exceptions.

4.7 Additional Equivalence Considerations

  • (1) None.

Parent topic: Part A - Large Yacht Code (up to 12 passengers)
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