Section 5 Shell envelope framing

5.1.1 The scantlings of bottom and side shell longitudinals are to comply with the requirements given in Table 12.5.1 Longitudinal stiffening.

5.1.2 For ships intended to operate aground, see Pt 4, Ch 12, 7 Bottom strengthening for operating aground.

5.2.1 For bottom structure with transverse framing, see Pt 4, Ch 12, 6 Bottom structure.

5.2.2 For ships intended to operate aground, see Pt 4, Ch 12, 7 Bottom strengthening for operating aground.

5.2.3 The scantlings of side frames amidships are to be in accordance with Pt 4, Ch 1, 6 Shell envelope framing for ships classed for unrestricted service or 100A1 extended protected waters service. The modulus of side frames may be reduced by eight per cent for ships classed A1 protected waters service.

5.3.1 The spacing of transverses supporting side longitudinals is generally to be in accordance with Pt 4, Ch 1, 6.4 Primary supporting structure, but is not to exceed 4,0 m.

5.3.2 Transverses supporting side longitudinals are to comply with the requirements of Pt 4, Ch 1, 6.4 Primary supporting structure, except for ships classed with a service restriction notation and all ships classed A1 protected waters service, where the requirements are given in Table 12.5.2 Primary supporting structure at sides.

5.3.3 In way of transverse framing, web frames may be required in way of hopper cross members. Alternative arrangements may be submitted for consideration.

5.3.4 The end connections of side transverses and web frames to deck and bottom transverses abreast of spoil spaces are to be arranged to prevent shear buckling of the members' webs.

5.3.5 For wash bulkheads fitted in lieu of web frames abreast spoil spaces, see Pt 4, Ch 12, 8.3 Spoil space and well boundaries 8.3.6.

Table 12.5.1 Longitudinal stiffening

Position of longitudinals	Modulus
(1) Bottom
	where l e = effective span of longitudinals, in metres, and is to be taken as not less than 1,85m except as provided for in Pt 4, Ch 12, 6.3 Single bottoms longitudinally framed 6.3.1
	= In way of single bottoms
	H = D
	= In way of double bottoms
	H = D on ships classed 100A1 or 100A1 extended protected waters service
	= T m for ships classed A1 protected waters service
	c = a factor varying from 1,0 at to at bottom, intermediate values by interpolation. For ships with hogging still water bending moments in loaded conditions and for split hull vessels, c = 1,0
	F B = as defined in Pt 3, Ch 4, 5.1 Symbols
	K 1 = 120 on ships classed 100A1 or 100A1 extended protected waters service
	= 150 on ships classed A1 protected waters service
	k = higher tensile steel factor, see Pt 3, Ch 2, 1 Materials of construction
(2) Side shell	(a) For ships classed 100A1 or 100A1 extended protected waters service The minimum modulus of side longitudinals is to be in accordance with Pt 4, Ch 1, 6.2 Longitudinal stiffening. (b) For ships classed A1 protected waters service The modulus required by (a) and reduced by 5 per cent
(3) Bilge	The scantlings of bilge longitudinals are to be graduated between those required for the bottom longitudinals and the lowest side longitudinals

Table 12.5.2 Primary supporting structure at sides

Symbols		Item	Requirement
h =	vertical distance from mid-point of span to deck at side, in metres		All ships classed 100A1 extended protected waters service: Z = 9,5Shl e 2cm3
l e =	effective length of supporting member, in metres, see Pt 3, Ch 3, 3 Structural idealisation	Transverses supporting side longitudinals amidships
			All ships classed A1 protected waters service: Z = 9,0Shl e 2cm3
=	moment of inertia of supporting member, in cm4 , see Pt 3, Ch 3, 3 Structural idealisation
S =	spacing, or mean spacing, of supporting member, in metres
		Transverses and web frames supporting side longitudinals abreast of spoil spaces	Inertia of not less than: = 2,5l e Z cm4
Z =	section modulus of supporting member, in cm3 , see Pt 3, Ch 3, 3 Structural idealisation