Part D
Subdivision
16 Collision Bulkheads
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16.1 A new vessel of 20 m or more in length is required to have a collision bulkhead fitted in accordance with regulations III/17.1 and III/17.2.
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16.2 A new vessel of less than 20 m in length shall have a collision bulkhead where it—
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.1 carries 50 or more passengers; or
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.2 is of more than 12m in length and is certified to operate on coastal waters; or
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.3 is certified to operate on exposed waters.
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16.3 A ro ro ferry of 20m or more in length that may operate on its route ahead or astern shall, in addition to the collision bulkhead required by III/16.1 is required to have a collision bulkhead fitted in accordance with regulations III/17.1 and III/17.3.
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16.4 The Administration shall determine the extent to which this regulation is applied to existing vessels.
17 Construction and Location of Collision Bulkheads
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17.1 Each collision bulkhead required by regulation III/16 shall be constructed in accordance with regulation III/18 except that it shall—
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.1 extend to the weather deck or to one deck above the bulkhead deck, whichever is lower, in vessels certified to operate on coastal and exposed waters; and
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.2 not be fitted with any type of penetration or opening except penetrations may be made where they are located as high and as far inboard as practicable and they have a means to make them watertight.
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17.2 The forward collision bulkhead required to be on a vessel by regulation III/16 shall be—
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.1 located at least 5% but not more than 15% of the length between perpendiculars (LBP) aft of the forward perpendicular or for vessels with bulbous bows extending forward of the forward perpendicular and contributing more than 2% of the underwater volume of the vessel the bulkhead shall be located at least 5% but not more than 15% of the LBP aft of the mid-length of such extension; and
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.2 installed in a single plane, with no recess or step, up to the bulkhead deck.
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17.3 The after collision bulkhead on a double-ended ferry of 20m (65 feet) or more in length required by regulation III/16.3 shall be—
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.1 located at least 5% but not more than 15% of the LBP forward of the after perpendicular and; shall be
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.2 installed in a single plane, with no recess or step, at least up to the bulkhead deck.
18 Watertight Subdivision Bulkheads
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18.1 Where a vessel is required to be fitted with watertight collision or subdivision bulkheads, each watertight bulkhead shall be of sufficient strength to be capable of remaining watertight with a head of water to the top of the bulkhead.
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18.2 Each watertight bulkhead shall extend to the bulkhead deck and shall be installed in one plane without steps or recesses insofar as in reasonable and practicable. Any steps or recesses permitted shall comply with the applicable subdivision requirements in this chapter.
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18.3 The number of penetrations in a watertight bulkhead shall be minimised. A penetration in a watertight bulkhead shall be as high and as far inboard in the bulkhead as practicable, and made watertight.
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18.4 Sluice valves shall not be permitted in watertight bulkheads.
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18.5 A door fitted in a watertight bulkhead shall be of watertight construction and be kept closed at sea, unless opened at the discretion of the Master.
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18.6 The Administration shall determine the extent to which this regulation is applied to existing vessels.
19 Subdivision of Cargo Vessels
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A new cargo vessel of 12m or more in length shall be fitted with watertight bulkheads at each end of the main propulsion machinery space.
20 Subdivision of Passenger Vessels
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20.1 A new passenger vessel of 20m or more in length shall be fitted with watertight bulkheads fitted in accordance with regulation III/21.
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20.2 A new vessel of less than 20m in length shall have watertight bulkheads in accordance with regulation III/21, where it—
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.1 carries 50 or more passengers; or
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.2 is of more than 12m in length and is certified to operate on coastal waters; or
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.3 is certified to operate in exposed waters.
21 Location of Watertight Bulkheads for Subdivision
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21.1 The maximum distance between adjacent main transverse watertight bulkheads on a vessel, required by regulation III/20 to comply with this regulation, shall not be more than the smaller of the following—
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.1 one third of the length of the bulkhead deck; or
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.2 the distance given by the following equation—
d = (F)(f)(L)/D
where—
| F = | the floodable length factor from Table III/21.1; |
| f = | the effective freeboard in metres calculated for each pair of adjacent bulkheads in accordance with III/21.2; |
| L = | Length Over Deck in metres measured over the bulkhead deck; and |
| D = | the depth in metres (feet), measured amidships at a point one- quarter of the maximum beam out from the centreline, from the inside of the bottom planking or plating to the level of the top of the bulkhead deck. (See Figure III/21-1). |
TABLE III/21
TABLE OF FLOODABLE LENGTH FACTORS
| (d/L)x100 | F |
| 0 – 15 | 0.33 |
| 20 | 0.34 |
| 25 | 0.36 |
| 30 | 0.38 |
| 35 | 0.43 |
| 40 | 0.48 |
| 45 | 0.54 |
| 50 | 0.61 |
| 55 | 0.63 |
| 60 | 0.58 |
| 65 | 0.53 |
| 70 | 0.48 |
| 75 | 0.44 |
| 80 | 0.40 |
| 85 | 0.37 |
| 90 – 100 | 0.34 |
NOTE 1: Where—
| d = | distance in metres (feet) from the midpoint of the compartment to the forward-most point on the bulkhead deck excluding sheer; and |
| L = | length over deck in metres (feet) measured over the bulkhead deck. |
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NOTE 2: Intermediate values of floodable length factor may be obtained by interpolation.
Figure III/21-1
Transverse Location for Measuring Depth (D)
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21.2 The effective freeboard for each compartment is calculated by the following equation—
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f = (a+b)/2
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where—
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f = the effective freeboard in metres (feet).
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a = the freeboard in metres (feet) measured—
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.1 at the forward main transverse watertight bulkhead; and
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.2 from the deepest waterline to—
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.1 the top of the bulkhead deck on a flush deck vessel; and
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.2 where a vessel has a stepped bulkhead deck, then to the line shown in Figure III/21-2; or
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.3 where a vessel has an opening scuttle (porthole) below the bulkhead deck, then to the line shown in Figure III/21-3.
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b = the freeboard in metres (feet) measured—
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.1 at the aft main transverse watertight bulkhead; and
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.2 from the deepest waterline to—
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.1 the top of the bulkhead deck on a flush deck vessel;
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.2 where a vessel has a stepped bulkhead deck, the line shown in Figure III/21-2; or
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.3 where a vessel has an opening scuttle (porthole) below the bulkhead deck, the line shown in Figure III-21-3.
Figure III/21-2
Freeboard Measurement – Vessel with Stepped Bulkhead Deck
(a and b shown for two sample compartments)
Figure III/21-3
Freeboard Measurement – Vessel with Stepped Bulkhead Deck and a Porthole Below the Bulkhead Deck
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21.3 A vessel, required by regulation III/20 to be fitted with watertight bulkheads shall be measured and subdivided in accordance with the simplified subdivision calculation given in Annex 3
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