Section 4 Subdivision and Arrangement

401. General

The hull is to be subdivided into watertight compartments as required for the requested service and type notation.

402. Transverse watertight bulkheads

1. The following transverse watertight bulkheads are to be fitted in all craft :

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(1) A collision bulkhead

(2) A bulkhead at each end of the machinery space(s)

2. The watertight bulkheads are in general to extend to the freeboard deck. Afterpeak bulkheads may, however, terminate at the first watertight deck above the load line.

3. The watertight bulkheads in way of the raised quarter or sunken forecastle deck is to extend to the side deck.

4. For craft with two continuous decks and a large freeboard to the uppermost deck, the following provisions apply.

(1) When the draught is less than the depth of the second deck, only the collision bulkhead need extend to the uppermost continuous deck. The remaining bulkheads may terminate at the second deck.

(2) When the draught is greater than the depth to the second deck, the machinery bulkheads, with the exception of the afterpeak bulkhead, are to be watertight to the uppermost continuous deck.

5. In craft with a raised quarter deck, the watertight bulkheads within the quarter deck region are to extend to this deck.

403. Collision bulkhead

1. The distance from the forward perpendicular to the collision bulkhead is to be taken between the limits. However, for the wave piercer, the distance shall be in accordance with Society satisfactions.

minimum m

= length (m ) of the craft

2. Minor steps or recesses in the collision bulkhead are to be accepted, provided the requirements to minimum and maximum distances from the forward perpendicular comply with Par 1.

3. For craft having complete or long forward superstructures, the collision bulkhead is to extend to the deck above the freeboard deck. The extension need not be fitted directly over the bulkhead below, provided that the requirements to distances from the forward perpendicular are complied with, and that the part of the freeboard deck forming the step is watertight.

404. Openings and closing appliances

1. Openings may be accepted in watertight bulkheads except in that part of the collision bulkhead sit- uated below the freeboard deck.

2. Openings situated below the freeboard deck are to have watertight doors with signboards fitted on each door stipulating that the door be kept closed while the craft is at sea.

3. Openings in collision bulkhead above the freeboard deck are to have watertight doors or an equiv- alent arrangement. The number of openings in the bulkhead are to be the minimum that are com- patible with the craft design and normal operation.

4. Doors in watertight bulkheads are to be complied with the followings :

(1) Doors may be hinged or sliding.

(2) They are to be shown by suitable testing to be capable of maintaining the watertight integrity of the bulkhead.

(3) Such testing is to 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.

(4) 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 is to be verified by inspection and hose testing.

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5. 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 above 4.).

6. All watertight doors are to be capable of being operated when the craft is inclined up to 15¡ and fitted with means of indication in the operating compartment showing whether they are open or closed. All such doors are to be capable of being opened and closed locally from each side of the bulkhead.

7. Watertight doors are to 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.

8. Watertight doors are to be capable of being closed by remote control from the operating compart- ment in not less than 20 s and not more than 40 s, and are to be provided with an audible alarm, distinct from other alarms in the area, which will sound for at least 5s but no more than 10s be- fore the doors begin to move whenever the door is closed remotely by power, and continue sound- ing until the door is completely closed.

9. The power, control and indicators are to be operable in the event of main power failure, as re- quired by Pt 6 of the Rules. In passenger areas and areas where the ambient noise exceeds 85 dB A the audible alarm is to be supplemented by an intermittent visual signal at the door.

10.

11.

12.

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 above mentioned 6.

Where pipes, scuppers, electric cables, etc. are carried through watertight divisions, the arrange- ments for creating a watertight penetration are to 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 is to be maintained for at least 30 min with 10 % greater than that determined from the minimum permissible height of a downflooding opening and there should be no leakage through the penetration arrangement during this period.

Watertight bulkhead penetrations which are effected by continuous welding do not require proto- type testing. Valves on scuppers from weathertight compartments, included in the stability calcu- lations, are to have arrangements for remote closing from the operating station.

13. Where a ventilation trunk forms part of a watertight boundary, the trunk is to be capable of with- standing the water pressure that may be present taking into account the maximum inclination an- gle allowable during all stages of flooding.

405. Cofferdams

The installation of cofferdams is to be carried out in accordance with Pt 3, Ch for the Classification of Steel ship.

15, 304. of Rules

406. Hydrostatic and watertight tests

In the Classification Survey during Construction, hydrostatic and watertight tests are to be carried out in accordance with Pt 3, Ch 1, 209. of Rules for the Classification of Steel Ship.

407.

Inner bow doors

1. Where ro-ro craft are fitted with a bow loading openings, an inner bow door is to 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, is to be:

(1) weathertight to the deck above, which deck shall itself be weathertight 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.

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2. A craft is to be exempted from the requirement for such an inner bow door where one of the fol- lowing applies:

(1) the vehicle loading deck at the inner bow door position is above the design waterline 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 pro- ceeding 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:

(A) the bow loading door is not reached by waves or 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 the HSC Code 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 veri- fied against full-scale or model testing;

(B) bow loading openings lead to open ro-ro spaces provided with guard-rails or having freeing ports complying with the following (C).

(C) 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 are ei-

ther to be proven to be acceptable using tests according to (a) above or comply with the

following: (a) ≥ where :

: the total area of freeing ports on each side of the deck in m

: the length of the compartment in m ;

; and

(b) the craft is to maintain a residual freeboard to the deck of the ro-ro space of at least 1

m in the worst condition;

(c)

such freeing ports are to 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

(d) such freeing ports are to be fitted with closing devices or flaps to prevent water enter-

ing the deck of the ro-ro space whilst allowing water which may deck of the ro-ro space to drain.

accumulate on the

408. Other provisions for ro-ro craft

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 407. 2 (2) or 3 m above the design waterline.

2. Where vehicle ramps are installed to give access to spaces below the deck of the ro-ro space, their openings are to be capable of being closed weathertight to prevent ingress of water below.

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 407. 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.

4. The accesses referred to in the above mentioned in 2. and 3. are to be fitted with alarm indicators in the operating compartment.

5. Special category spaces and ro-ro spaces are to be patrolled or monitored by effective means, such as television surveillance, so that any movement of vehicles in adverse weather conditions and un- authorised access by passengers thereto can be detected whilst the craft is underway

409.

Integrity of superstructure

1. Where entry of water into structures above the datum would significantly influence the stability and buoyancy of the craft, such structures are to be one of the followings:

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(1) of adequate strength to maintain the weathertight integrity and fitted appliances; or

(2) provided with adequate drainage arrangements; or

(3) an equivalent combination of both measures.

2. Weathertight superstructures and deckhouses located above the datum are to have means of closing openings with sufficient strength such as to

with weathertight closing

in the outside boundaries maintain weathertight in-

tegrity in all damage conditions where the space in question is not damaged. Furthermore, the

means of closing are to be such as to maintain weathertight integrity in all operational conditions.

410. Doors, windows, etc., in boundaries of weathertight spaces

1. Doors, windows, etc., and any associated frames and mullions in weathertight superstructures and deckhouses are to be weathertight and are not to leak or fail at a uniformly applied pressure less than that at which adjacent structure would experience permanent set or fail.

2. For doors in weathertight superstructures, hose tests are to be carried out with a water pressure which is in accordance with Table 3.1.1 in Pt 3, Ch 1 of Rules for the Classification of Steel Ship.

3. The height above the deck of sills to doorways leading to exposed decks are to be as high above the deck as is reasonable and practicable, particularly those located in exposed positions. Such sill heights are to in general not be less than 100 mm for doors to weathertight spaces on decks above the datum, and 250 mm elsewhere. For craft of 30 m in length and under, sill heights may be re- duced to the maximum which is consistent with the safe working of the craft.

4. Windows are not to 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.

5. Side scuttles to spaces below the datum are to be fitted with efficient hinged deadlights arranged inside so that they can be effectively closed and secured watertight.

6. No side scuttle is to be fitted in a position so that its sill is below a line drawn parallel to and one metre above the design waterline.

411. Indicators and surveillance

1. Indicators are to 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.

2. The indicator system is to 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 ar- rangements become unsecured. The indicator panel in the operating compartment is to 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.

3. The power supply for the indicator systems is to be independent of the power supply for operating and securing the doors.

4. Television surveillance and a water leakage detection system are to be arranged to provide an in-

dication ner and

to the operating compartment and to the engine control station of any leakage through in- outer bow doors, stern doors or any other shell doors which could lead to major flooding.

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