2 Main vertical zones and horizontal zones (R 24)
NEW CLASS B, C AND D SHIPS:
.1.1In ships carrying more than 36 passengers, the hull, superstructure and deckhouses shall be subdivided into main vertical zones by A-60 class divisions.
Steps and recesses shall be kept to a minimum but where they are necessary, they shall also be A-60 class divisions.
Where an open deck space, a sanitary or similar space or a tank including a fuel oil tank, void space or auxiliary machinery space having little or no fire risk, is on one side or where fuel oil tanks are on both sides of the division the standard may be reduced to A-0.
NEW CLASS B, C AND D AND EXISTING CLASS B SHIPS:
.1.2For new class B, C and D ships carrying not more than 36 passengers and for existing class B ships carrying more than 36 passengers, the hull, superstructure and deckhouses in way of accommodation and service spaces shall be subdivided into main vertical zones by “A” class divisions. These divisions shall have insulation values in accordance with the tables in Regulation 5.
NEW CLASS B, C AND D SHIPS:
.2As far as practicable, the bulkheads forming the boundaries of the main vertical zones above the bulkhead deck shall be in line with watertight subdivision bulkheads situated immediately below the bulkhead deck. The length and width of main vertical zones may be extended to a maximum of 48 metres in order to bring the ends of main vertical zones to coincide with subdivision watertight bulkheads or in order to accommodate a large public space extending for the whole length of the main vertical zone provided that the total area of the main vertical zone is not greater than 1 600 m2 on any deck. The length or width of a main vertical zone is the maximum distance between the furthermost points of the bulkheads bounding it.
NEW CLASS B, C AND D SHIPS AND EXISTING CLASS B SHIPS CARRYING MORE THAN 36 PASSENGERS:
.3Such bulkheads shall extend from deck to deck and to the shell or other boundaries.
.4Where a main vertical zone is subdivided by horizontal “A” class divisions into horizontal zones for the purpose of providing an appropriate barrier between sprinkled and non-sprinklered zones of the ship, the divisions shall extend between adjacent main vertical zone bulkheads and to the shell or exterior boundaries of the ship and shall be insulated in accordance with the fire insulation and integrity values given in table 4.2 for new ships carrying more than 36 passengers, and existing class B ships carrying more than 36 passengers.
.5
On ships designed for special purposes, such as automobile or railroad car ferries where the provision of main vertical zone bulkheads would defeat the purpose for which the ship is intended, equivalent protection shall be obtained by dividing space in horizontal zones.
However, in a ship with special category spaces, any such space shall comply with the applicable provisions of Regulation II-2/B/14 and in so far as such compliance would be inconsistent with compliance with other requirements of this part, the requirements of Regulation II-2/B/14 shall prevail.