Chapter 1 General Comment and Requirements
1.15 Review of the Code
1.15.1 The Code shall be reviewed by the Organization at intervals preferably not exceeding six years to consider revision of existing requirements to take account of new developments in design and technology.
1.15.2 Where a new development in design and technology has been found acceptable to an Administration, that Administration may submit particulars of such development to the Organization for consideration for incorporation into the Code during periodical review.
Chapter 2
Buoyancy, Stability and Subdivision
Part A - General
C2.0 Documentation
C2.0.1 For the purpose of buoyancy, stability and subdivision of the high speed craft, following drawings and documents are to be submitted for approval.
.1 General arrangement .2 Midship section
.3 Construction profile and deck plan .4 Hydrostatic curves or tables .5 Stability curves
.6 Loading manual
.7 Intact stability calculations .8 Damage stability calculations
.9 Inclining test scheme and report of result .10 Damage control Plan
2.1 General
2.1.1 A craft shall be provided with:
.1 stability characteristics and stabilization systems adequate for safety when the craft is operated in the non-displacement mode and during the transitional mode;
.2 buoyancy and stability characteristics adequate for safety where the craft is operated in the displacement mode, both in the intact condition and the damaged condition; and
.3 stability characteristics in the non-displacement and transitional modes adequate to transfer the craft safely to displacement mode in case of any system malfunction
2.1.2 Account shall be taken of the effect of icing in the stability calculations. An example of established practice for ice accretion allowances is given in annex 5 for the guidance of the Administration.
2.1.3 For the purpose of this and other chapters, unless expressly defined otherwise, the following definitions apply:
.1 "Downflooding point" means any opening, irrespective of size, that would permit passage of water through a water/weathertight structure (e.g., opening windows), but excludes any opening kept closed to an appropriate standard of water/weathertightness at all times other than when required for access or for operation of portable submersible bilge pumps in an emergency (e.g., non-opening windows of similar strength and weathertight integrity to the structure in which they are installed).
.2 Elsewhere when applied to sill and coaming heights in 2.2.7 and 2.2.8 is taken as applying to all weathertight and watertight closures located on or below the datum.
.3 "Fully submerged foil" means a foil having no lift components piercing the surface of the water in the foil-borne mode.
.4 "Mono-hull craft" means any craft which is not a multi-hull craft.
.5 "Multi-hull craft" means a craft which in any normally achievable operating trim or heel angle, has a rigid hull structure which penetrates the surface of the sea over more than one discrete area.
.6 "Permeability" of a space means the percentage of the volume of that space which can be occupied by water.
.7 "Skirt" means a downwardly extending, flexible structure used to contain or divide an air cushion.
2.1.4 Other means of demonstrating compliance with the requirements of any part of this Chapter may be accepted, provided that the method chosen can be shown to provide an equivalent level of safety. Such methods may include:
.1 mathematical simulation of dynamic behavior;
.2 scale model testing; and .3 full-scale trials.
2.1.5 The adequacy of mathematical simulations must first be demonstrated by correlation with full-scale or model tests for the appropriate type of craft. It may be appropriate to use mathematical simulations to help to identify the more critical scenarios for subsequent physical testing.
2.1.6 Model or full-scale tests and/or calculations (as appropriate) shall also include consideration of the following known stability hazards to which high-speed craft are known to be liable, according to craft type:
.1 directional instability, which is often coupled to roll and pitch instabilities;
.2 broaching and bow diving in following seas at speeds near to wave speed, applicable to most types;
.3 bow diving of planning mono-hulls and catamarans due to dynamic loss of longitudinal stability in relatively calm seas;
.4 reduction in transverse stability with increasing speed of mono-hulls;
.5 porpoising of planning mono-hulls, being coupled pitch and heave oscillations, which can become violent;
.6 chine tripping, being a phenomenon of planning mono-hulls occurring when the immersion of a chine generates a strong capsizing moment;
.7 plough-in of air-cushion vehicles, either longitudinal or transverse, as a result of bow or side skirt tuck-under or sudden collapse of skirt geometry, which, in extreme cases, can result in capsize;
.8 pitch instability of SWATH (small water-plane area twin hull) craft due to the hydrodynamic moment developed as a result of the water flow over the submerged lower hulls;
.9 reduction in effective metacentric height (roll stiffness) of surface effect ship (SES) in high speed turns compared to that on a straight course, which can result in sudden increases in heel angle and/or coupled roll and pitch oscillations; and
.10 resonant rolling of SES in beam seas, which, in extreme cases, can result in capsize.
2.1.7 Suitable calculations shall be carried out and/or tests conducted to demonstrate that, when operating within approved operational limitations, the craft will, after a disturbance causing roll, pitch, heave or heel due to turning or any combination thereof, return to the original attitude. Where calculations are employed, it shall first be shown that they correctly represent dynamic behaviour within the operational limitations of the craft.
C2.1.7 Watertight bulkheads
.1 All craft are to be fitted, at least, with following watertight bulkheads：
- a collision bulkhead,
- a bulkhead each at both ends of the machinery space
.2 The collision bulkhead is to be located within the range in 0.05L and 0.05L+3 m from forward perpendicular.
2.2 Intact buoyancy and watertight and weather-tight integrity
2.2.1 Buoyant Spaces
2.2.1.1 All craft shall have a sufficient reserve of buoyancy at the design waterline to meet the intact and damage stability requirements of this chapter. The Administration may require a larger reserve of buoyancy to permit the craft to operate in any of its intended modes. This reserve of buoyancy shall be calculated by including only those compartments that are:
Some mathematical simulation methods are not well suited to accurate modelling of extreme events. For safety level 3 or 4, it may be appropriate to use model testing as a precursor to, or instead of , full-scale testing.
.1 watertight and situated below the datum, or
.2 watertight or watertight and situated above the datum.
In considering the stability after damage, flooding shall be assumed to occur until limited by watertight boundaries in the equilibrium condition, and weather-tight boundaries in intermediate stages of flooding and within the range of positive righting lever required to satisfy the residual stability requirements. Where a buoyant space may be subjected to increased fluid pressure in the equilibrium position after damage, the boundaries and associated openings and penetrations of that space shall be designed and constructed to prevent the passage of fluid under that pressure.
Craft built in conformity with the requirements of organizations recognized by the Administration, in accordance with regulation XI/1 of the Convention may be considered to possess adequate strength and integrity.
2.2.1.2 Arrangements shall be provided for checking the watertight or weather-tight integrity of those compartments taken into account in 2.2.1.1, and the details incorporated in the Craft Operating Manual required by 18.2.1.
2.2.2 Openings in watertight divisions
2.2.2.1 The number of openings in watertight bulkheads shall be reduced to the minimum compatible with the design and proper working of the craft, and all such doors shall be closed prior to departure of the craft from the berth.
2.2.2.2 Doors in watertight bulkheads may be hinged or sliding. They shall be shown by suitable testing to be capable of maintaining the watertight integrity of the bulkhead. Such testing shall be carried out for both sides of the door and shall apply a pressure head 10% greater than that determined from the minimum permissible height of a down-flooding opening. Testing may be carried out either before or after the door is fitted into the craft but, where shore testing is adopted, satisfactory installation in the craft shall be verified by inspection and hose testing.
2.2.2.3 Type approval may be accepted in lieu of testing individual doors, provided the approval process includes pressure testing to a head equal to, or greater, than the required head (refer to 2.2.2.2).
2.2.2.4 All watertight doors shall be capable of being operated when the craft is inclined up to 15°, and shall be fitted with means of indication in the operating compartment showing whether they are open or closed. All such doors shall be capable of being opened and closed locally from each side of the bulkhead.
2.2.2.5 Watertight doors shall remain closed when the craft is at sea, except that they may be opened for access. A notice shall be attached to each door to the effect that it is not to be left open.
2.2.2.6 Watertight doors shall be capable of being closed by remote control from the operating compartment in not less than 20 s and not more than 40 s, and shall be provided with an audible alarm, distinct from other alarms in the area, which will sound for at least 5 s but no more than 10 s before the doors begin to move whenever the door is closed remotely by power, and continue sounding until the door is completely closed. The power, control and indicators shall be operable in the event of main power failure, as required by regulation II-1/15.7.3 of the Convention. In passenger areas and areas where the ambient noise exceeds 85 dB(A) the audible alarm shall be supplemented by an intermittent visual signal at the door. If the Administration is satisfied that such doors are essential for the safe work of the craft, hinged watertight doors having only local control may be permitted for areas to which crew only have access, provided they are fitted with remote indicators as required by 2.2.2.4.
2.2.2.7 Where pipes, scuppers, electric cables, etc. are carried through watertight divisions, the arrangements for creating a watertight penetration shall be of a type which has been prototype tested under hydrostatic pressure equal to or greater than that required to be withstood for the actual location in the craft in which they are to be installed. The test pressure shall be maintained for at least 30 min and there must be no leakage through the penetration arrangement during this period. The test pressure head shall be 10% greater than that determined from the minimum permissible height of a down-flooding opening. Watertight bulkhead penetrations which are effected by continuous welding do not require prototype testing. Valves on scuppers from weather-tight compartments, included in the stability calculations, shall have arrangements for remote closing from the operating station.
2.2.2.8 Where a ventilation trunk forms part of a watertight boundary, the trunk shall be capable of withstanding the water pressure that may be present taking into account the maximum inclination angle allowable during all stages of flooding.
2.2.3 Inner bow doors
2.2.3.1 Where ro-ro craft are fitted with bow loading openings, an inner bow door shall be fitted abaft such openings, to restrict the extent of flooding in the event of failure of the outer closure. This inner bow door, where fitted, shall be:
.1 weather-tight to the deck above, which deck shall itself be weather-tight forward to the bow loading opening;
.2 so arranged as to preclude the possibility of a bow loading door causing damage to it in the case of damage to, or detachment of, the bow loading door;
.3 forward of all positions on the vehicle deck in which vehicles are intended to be carried; and .4 part of a boundary designed to prevent flooding into the remainder of the craft.
2.2.3.2 A craft may be exempted from the requirement for such an inner bow door where one of the following applies:
.1 the vehicle loading deck at the inner bow door position is above the design water-line by a height more than the significant wave height corresponding to the worst intended conditions;
.2 it can be demonstrated using model tests or mathematical simulations that when the craft is proceeding at a range of speeds up to the maximum attainable speed in the loaded condition at all headings in long crested seas of the greatest significant wave height corresponding to the worst intended conditions, either:
.2.1 the bow loading door is not reached by waves; or
.2.2 having been tested with the bow loading door open to determine the maximum steady state volume of water which accumulates, it can be shown by static analysis that, with the same volume of water on the vehicle deck(s) the residual stability requirements of 2.6.11 and 2.13 or 2.15 are satisfied. If the model tests or mathematical simulations are unable to show that the volume of water accumulated reaches a steady state the craft shall be considered not to have satisfied the conditions of this exemption.
Where mathematical simulations are employed they shall already have been verified against full-scale or model testing;
.3 bow loading openings lead to open ro-ro spaces provided with guard-rails or having freeing ports complying with 2.2.3.2.4;
.4 the deck of the lowest ro-ro space above the design waterline is fitted on each side of the deck with freeing ports evenly distributed along the sides of the compartment. These shall either be proven to be acceptable using tests according to 2.2.3.2.2 above or comply with the following:
.4.1 A > 0.3 l where :
A = the total area of freeing ports on each side of the deck (m2)；and l = the length of the compartment in m;
.4.2 the craft shall maintain a residual freeboard to the deck of the ro-ro space of at least 1 m in the worst condition;
.4.3 such freeing ports shall be located within the height of 0.6 m above the deck of the ro-ro space, and the lower edge of the ports shall be within 0.02 m above the deck of the ro-ro space; and
.4.4 such freeing ports shall be fitted with closing devices or flaps to prevent water entering the deck of the ro-ro space whilst allowing water which may accumulate on the deck of the ro-ro space to drain.
2.2.4 Other provisions for ro-ro craft
2.2.4.1 All accesses in the ro-ro space that lead to spaces below the deck shall have a lowest point which is not less than the height required from the tests conducted according to 2.2.3.2.2 or 3 m above the design waterline.
2.2.4.2 Where vehicle ramps are installed to give access to spaces below the deck of the ro-ro space, their openings shall be capable of being closed weather-tight to prevent ingress of water below.
2.2.4.3 Accesses in the ro-ro space that lead to spaces below the ro-ro deck and having a lowest point which is less than the height required from the tests conducted according to 2.2.3.2.2 or 3 m above the design waterline may be permitted provided they are watertight and are closed before the craft leaves the berth on any voyage and remain closed until the craft is at its next berth.
2.2.4.4 The accesses referred to in 2.2.4.2 and 2.2.4.3 above shall be fitted with alarm indicators in the operating compartment.
2.2.4.5 Special category spaces and ro-ro spaces shall be patrolled or monitored by effective means, such as television surveillance, so that any movement of vehicles in adverse weather conditions and unauthorized access by passengers thereto can be detected whilst the craft is underway (refer to 7.8.3.1).
2.2.5 Indicators and surveillance 2.2.5.1 Indicators
Indicators shall be provided in the operating compartment for all shell doors, loading doors and other closing appliances which, if left open or not properly secured, could lead to major flooding in the intact and damage conditions.
The indicator system shall be designed on the fail-safe principle and shall show by visual alarms if the door is not fully closed or if any of the securing arrangements are not in place and fully locked, and by audible alarms if such door or closing appliance becomes open or the securing arrangements become unsecured. The indicator panel in the operating compartment shall be equipped with a mode selection function 'harbour /sea voyage' so arranged that an audible alarm is given in the operating compartment if the craft leaves harbour with the bow doors, inner doors, stern ramp or any other side shell doors not closed or any closing device not in the correct position. The power supply for the indicator systems shall be independent of the power supply for operating and securing the doors.
2.2.5.2 Television surveillance
Television surveillance and a water leakage detection system shall be arranged to provide an indication to the operating compartment and to the engine control station of any leakage through inner and outer bow doors, stern doors or any other shell doors which could lead to major flooding.
2.2.6 Integrity of superstructure
2.2.6.1 Where entry of water into structures above the datum would significantly influence the stability and buoyancy of the craft, such structures shall be:
.1 of adequate strength to maintain the weathertight integrity and fitted with weather-tight closing appliances;or .2 provided with adequate drainage arrangements; or
.3 an equivalent combination of both measures.
2.2.6.2 Weather-tight superstructures and deckhouses located above the datum shall in the outside boundaries have means of closing openings with sufficient strength such as to maintain weather-tight integrity in all damage conditions where the space in question is not damaged. Furthermore, the means of closing shall be such as to maintain weather-tight integrity in all operational conditions.
2.2.7 Doors, windows, etc., in boundaries of weather-tight spaces
2.2.7.1 Doors, windows, etc., and any associated frames and mullions in weather-tight superstructures and deckhouses shall be weather-tight and shall not leak or fail at a uniformly applied pressure less than that at which adjacent structure would experience permanent set or fail. Conformity with the requirements of organizations recognized by the Administration in accordance with regulation XI/1 of the Convention may be considered to possess adequate strength.
2.2.7.2 For doors in weather-tight superstructures, hose tests shall be carried out with a water pressure from the outside in accordance with specifications at least equivalent to those acceptable to the Organization.
2.2.7.3 The height above the deck of sills to doorways leading to exposed decks shall be as high above the deck as is reasonable and practicable, particularly those located in exposed positions. Such sill heights shall in general not be less than 100 mm for doors to weather-tight spaces on decks above the datum, and 250 mm elsewhere. For craft of 30 m in length and under, sill heights may be reduced to the maximum which is consistent with the safe working of the craft.
2.2.7.4 Windows shall not be permitted in the boundaries of special category spaces or ro-ro spaces or below the datum. If required by restrictions in the Permit to Operate, forward facing windows, or windows which may be submerged at any stage of flooding shall be fitted with hinged or sliding storm shutters ready for immediate use.
2.2.7.4 Windows shall not be permitted in the boundaries of special category spaces or ro-ro spaces or below the datum. If required by restrictions in the Permit to Operate, forward facing windows, or windows which may be submerged at any stage of flooding shall be fitted with hinged or sliding storm shutters ready for immediate use.