Section 2 Hull envelope plating

2.1.1 This Section covers the requirements for hull envelope plating, which includes keel, stem, bottom shell plating, bilge plating, side shell plating, sheerstrake and deck plating for the fore end and aft end of the ship. Requirements are also given for tapering between the end thickness and the midship 0,5L thickness.

2.2.1 The scantlings of bar keels at the ends are to comply with Table 5.2.1 Shell plating forward and aft.

2.2.2 The thickness of the keel plate forward of the collision bulkhead is to be the stem plate thickness; aft of the collision bulkhead the keel plate thickness is to be as required for the midship region. The width of the keel plate is to be 0,1B at the collision bulkhead and may be tapered towards the stem.

2.2.3 The thickness of the keel plate aft is to be as required for the midship region. The width of the keel plate is to be 0,1B at the aft peak bulkhead and may be tapered towards the aft end.

2.3.1 Bar stems may be rolled steel bars or steel forgings complying with the relevant requirements of the Rules for the Manufacture, Testing and Certification of Materials, July 2022 (hereinafter referred to as Rules for Materials). The scantlings of bar stems are to comply with Table 5.2.1 Shell plating forward and aft.

2.3.2 The thickness of plate stems is to be determined from Table 5.2.1 Shell plating forward and aft. Plate stems are to be supported by horizontal diaphragms, spaced about 1 m apart and extended to the nearest frame. Where the stem plate radius is large, a centreline stiffener or web will be required. The thickness of plate stems from 1 m above the deepest load waterline may be equal to the local shell thickness.

2.3.3 For sternframe details, see Pt 3, Ch 5, 8 Sternframes and appendages.

2.4.1 The thickness of bottom shell, bilge and side shell plating in the forward and aft region is to comply with Table 5.2.1 Shell plating forward and aft, but may require to be increased as per Pt 3, Ch 5, 4.2 Shell framing 4.2.3.

2.4.2 The amidships thickness of the bilge plating is to be extended forward and aft to include the shoulders of the bilge. The shoulder is regarded to extend to where the upper edge of the bilge strake forward and aft reaches the point 0,5B — 0,5 m.

2.4.3 Where a bilge chine bar is used in a bilge arrangement, the scantlings of chine bars are to comply with Table 5.2.1 Shell plating forward and aft, and adjacent bottom and side shell plating need not be increased in thickness.

2.4.4 The thickness of side shell and sheerstrake plating in the forward and aft region may require to be increased locally in accordance with Pt 3, Ch 4 Longitudinal Strength, on account of high shear forces, or the presence of steps or breaks in decks, see Pt 3, Ch 5, 1.3 Structural continuity 1.3.3.

2.4.5 The thickness of shell plating is to be increased locally in way of the sternframe, propeller brackets and rudder trunks. The increased plate thickness is to be not less than 50 per cent greater than the basic shell end thickness. The shell plating in way of hawse pipes is to be increased in thickness by 3 mm.

2.4.6 Where a swim end is arranged, the bottom shell plating thickness amidships is to be maintained up to the end of the rake plating.

2.5.1 In general, compensation will not be required for holes in the shell plating forward and aft, provided the holes are of well rounded shape, but reinforcements in way of large openings may be required.

2.6.1 The thickness of deck plating is to comply with the requirements of Table 5.2.2 Deck plating forward and aft.

Table 5.2.2 Deck plating forward and aft

Location	Thickness, in mm
(1) Forward of 0,075L from the F.P. and aft of 0,075L from the A.P. on the strength deck	The greatest of: t = (5,6 + 0,039L) t = 10s
(2) Between 0,075L and 0,25L from the F.P. and between 0,075L and 0,25L from the A.P. on the strength deck	The greatest of: t = (5,6 + 0,039L) t = 10s t = the taper thickness see Note
(3) Platform decks	The greater of: t = 8s t = 3,5
(4) In way of crown or bottom of a tank	The greater of: t = as required in Pt 3, Ch 7 Bulkheads t as in (1), (2) or (3) as applicable, but not less than t = 5 mm for oil tanks, or t = 5,5 mm for water ballast tanks
(5) Plating forming the upper flange of under deck girders	The greater of: t = with a minimum breadth b = 0,75 m t as in (1), (2), (3) or (4) as applicable
Symbols
L, s and t are as defined in Pt 3, Ch 5, 1.4 Symbols and definitions 1.4.1 A f = girder face area, in cm2 b = breadth of increased plating, in metres k = higher tensile steel factor, see Pt 3, Ch 2, 1.3 Steel 1.3.3
Note For taper area requirements, see also Pt 3, Ch 5, 2.6 Deck plating 2.6.2.

2.6.2 For ships with wide hatch openings, in addition to the requirements for minimum deck thickness forward given in Pt 3, Ch 5, 2.6 Deck plating 2.6.1, the total cross-sectional area of strength deck plating and longitudinal stiffening outside the line of main hatch openings is to be not less than that obtained from a taper line constructed as shown in Figure 5.2.1 Strength deck area taper.

Figure 5.2.1 Strength deck area taper

2.6.3 The deck plating thickness and supporting structure are to be suitably reinforced in way of the anchor windlass, steering gear and other deck machinery, and in way of bollards, cranes, masts or derrick posts.

2.6.4 For steps and breaks, see Pt 3, Ch 5, 1.3 Structural continuity 1.3.3.

2.7.1 Compensation and edge reinforcement for openings in the upper deck forward of 0,25L from the F.P. and aft of 0,25L from the A.P. may be required.