Section 2 Construction of Watertight Bulkheads

201. Thickness of Bulkhead Laminates of Single Skin Construction

The thickness of bulkhead laminates of single skin construction is not to be less than obtained from the following formula:

ᾼ Ņ ÌĪĊΡ̓Üᾜ Nmm Ń

where,

Ċ : Spacing of stiffeners (m ).

ᾜ : Vertical distance from the lower edge of bulkhead laminate to the top of upper deck laminate at the centre line of the ship (m ). However, for the collision bulkhead, the value specified

above is to be multiplied by 1.25.

202. Thickness of Bulkhead Laminates of Sandwich Construction

1. The aggregated thickness of the inner layers, outer layers and cores of bulkhead laminates of sand- wich construction is not to be less than obtained from the following formulae, whichever is greater:

ᾼÌ Ņ ǼÌĊᾜ Nmm Ń ᾼĪ Ņ ǼĪᾼᾚ Nmm Ń

where,

ᾼᾚ : Thickness in case of single skin construction specified in 201. (mm ).

Ċ : Spacing of stiffeners (m ).

ᾜ : As specified in 201. (m ).

ǼÌ and ǼĪ : As specified in Ch 6, 303. 1.

2. The respective thicknesses of the inner layers and outer layers of bulkhead laminates of sandwich construction are not, notwithstanding the requirements in the preceding 1, to be less than obtained from the following formula. In no case, however, is it less than 2.4 mm .

Ĩ

ᾼ Ņ ĮǾĴΡ̓Į ÜǼ NĊᾜŃĨ Nmm Ń

where,

Ċ : Spacing of stiffeners (m ).

ᾜ : As specified in 201. (m ).

ǼĨ : As specified in Ch 6, 303. 2.

203. Bulkhead Laminates of Structural Plywood 【See Guidance】

Where structural plywoods are used for bulkhead plates, the thickness of plywoods is not to be less than specified by the requirements in 201. multiplied by the coefficient given in Ch 1, 304. 2 (1). However, ſſÆ is to be taken as bending strength (kgÕmmĪ ) of plywoods.

204. Bulkheads Stiffeners

The section modulus of bulkhead stiffeners is not to be less than obtained from the following for- mula:

Ě Ņ ǼĊᾜᾨĪ NcmĮŃ

where,

ᾨ : Total length between adjacent supports of stiffener (m ) including the length of connection at the end. Where, however, girders are provided, l is the distance from the heel of end connection to the nearest girder or the distance between girders.

ᾜ : 0.8 times the vertical distance from the mid-point of l to the top of upper deck laminate at the centre line of ship plus 1.2 (m ). However, for the collision bulkhead, the above men- tioned value is to be multiplied by 1.25.

Ċ : Spacing of stiffeners (m ).

Ǽ : Coefficient given below:

(1) Where the both ends of stiffeners are attached by brackets : 20

(2) Where the ends of stiffeners are snipped : 30

205. Girders supporting Bulkhead Stiffeners

Webs of girders supporting bulkhead stiffeners are to be connected to the bulkhead laminates and the section modulus of girders is not to be less than obtained from the following formula:

Ě Ņ ĮĨĊᾜᾨĪ NcmĮ Ń

where,

ᾨ : Total length of girders including the length of end connection (m ).

Ċ : Breadth of the area supported by the girders (m ).

ᾜ : 0.8 times the vertical distance from the mid-point of Ċ to the top of upper deck laminate

at the centre line of ship plus 1.2 (m ). However, for the collision mentioned value is to be multiplied by 1.25.

bulkhead, the above

206. Hat-type Construction

The scantlings of bulkhead stiffeners and girders of hat-type construction are to be in accordance with the requirements in Ch 1, 305. in addition to those in this chapter.