3.1 General
3.1.1 Where the shell is longitudinally framed in the midship region, this system of framing is to be carried as far forward as practicable. In the case of oil tankers, longitudinal framing is to extend at least to the forward end of the cargo tanks.
3.2 Keel
3.2.1 The scantlings of bar keels at the fore end are to be the same as in the midship region as required by Pt 4, Ch 1,5.
3.2.2 The thickness and width of plate keels in the forward region are to be the same as required in the midship region for the particular type of ship concerned, see Part 4.
3.3 Stem
3.3.1 Bar stems may be either steel castings or steel forgings complying with the requirements of Chapter 3 of the Rules for Materials (Part 2) for rolled steel flat bars or Chapter 5 of the Rules for Materials (Part 2) for solid round bars. The scantlings of bar stems are to comply with Table 5.3.1.
3.3.2 The scantlings of plate stems are to be determined from Table 5.3.1. Plate stems are to be supported by hori- zontal diaphragms positioned in line with the side stringers or perforated flats with intermediate breasthook diaphragms. Diaphragms are to be spaced not more than 1,5 m apart, measured along the stem. Where the stem plate radius is large, a centreline stiffener or web will be required.
3.4 Bottom shell and bilge
3.4.1 The thickness of bottom shell and bilge plating in the forward region for ships not requiring additional strengthening of bottom is to comply with Table 5.3.1.
3.4.2 For thickness of bottom shell and keel when additional bottom strengthening is required, see 1.5.
3.4.3 Where longitudinals are omitted in way of radiused bilge plating amidships, the plating thickness forward will be considered in relation to the support derived from the hull form and internal stiffening arrangements.
3.5 Side shell and sheerstrake
3.5.1 The thickness of side shell and sheerstrake plating in the forward region is to be not less than the values given in Table 5.3.1, but may be required to be increased locally on account of high shear forces, in accordance with Ch 4,6.5.
3.5.2 For transversely framed side shells where panting stringers are omitted, see 4.4, the side shell plating in the region concerned is to be increased in thickness by the percentages given below:
(a) 15 per cent, where L£150 m (b) 5 per cent, where L³215 m
For intermediate values of L, the percentage increase is to be obtained by interpolation.
3.5.3 The side shell plating of increased thickness required by 3.5.2 is to be continued forward past the fore peak or collision bulkhead. In addition, horizontal brackets in line with the fore peak stringers are to be fitted at the aft side of the bulkhead where practicable. The brackets are to be the same thickness as the side shell and are to extend from the bulkhead to the adjacent shell frame and be connected thereto. Transversely the toes of the brackets are to extend past the outboard stiffener of the bulkhead to clear any cut out in the bulkhead stringer.
3.5.4 The sheerstrake taper thickness is to be increased by 20 per cent at the ends of a bridge superstructure extending out to the ship's side irrespective of position. Similar strengthening is to be fitted in way of the end of a forecastle if this occurs at a position aft of 0,25L from the F.P. No increase is required if the forecastle end bulkhead lies forward of 0,2L from the F.P. The increase at intermediate positions of end bulkhead is to be obtained by interpolation.
3.5.5 The shell plating may be required to be increased in thickness locally in way of hawse pipes, see Ch 13,7.8.
3.5.6 The shell plating is to be increased in thickness locally in way of a bulbous bow, see 6.5.6.
3.6 Shell openings
3.6.1 In general, compensation will not be required for holes in the sheerstrake which are clear of the gunwale, or for any deck openings situated outside the line of main hatch- ways and whose depth does not exceed 20 per cent of the depth of the sheerstrake or 380 mm, whichever is the lesser. Openings are not to be cut in a rounded gunwale. Cargo door openings are to have well rounded corners, and the proposed compensation for the door openings will be individually considered.
3.6.2 Sea inlet and other openings are to have well rounded corners. The thickness of sea inlet box plating is generally to be the same as the adjacent shell. It is however, to be not less than 12,5 mm, and need not exceed 25 mm.
Part 3, Chapter 5
Section 3Fore End Structure
RULES ANDREGULATIONS FOR THECLASSIFICATION OFSHIPS, July 2000
Part 3, Chapter 5
Section 3LLOYD’SREGISTER OFSHIPPING 13
NOTES
1. For ships where L£ 70 m this thickness may be reduced by 1 mm, but it is to be not less than 6 mm.
2. The taper thickness is to be determined from Table 3.2.1 in Chapter 3.
3. For thickness of shell plating in way of the cargo and fore peak tanks of oil tankers or ore carriers, see also Pt 4, Ch 9, Ch 10 or Ch 11, as appropriate. 4. In offshore supply ships the thick-
ness of side shell is to be not less than 9 mm.
5. For trawlers and fishing vessels,
see Pt 4, Ch 6,5.
6. For fast cargo ships, see Pt 4, Ch 1,3.
7. For oil tankers the thickness is also to be in accordance with Pt 4, Ch 9,4.3.3.
A1 = (1,6L – 32) cm2or L cm2 whichever is the greater
A2 = 0,75 A1 cm2
t =
(
5,0 + 0,083L2)
k mm t = as (2)(a) for side shellTable 5.3.1 Shell plating forward
Location Thickness, in mm
(1) Bottom shell and bilge, see also 1.5 and Note 5:
(a) Forward of 0,075L from the F.P. (b) Between 0,075L and 0,25L from
the F.P., see Note 7
(c) Aft of 0,25L from the F.P., see Note 7 (2) Side shell, see Notes 4 and 5:
(a) Forward of 0,075L from the F.P. (b) Between 0,075L and 0,2L from the F.P.,
see also 3.5.2
(c) Aft of 0,2L from the F.P.
(4) Forecastle, see Notes 4 and 5 (5) Stem, see Notes 4 and 5:
(a) Bar stem: below load waterline at stem head (b) Plate stem: below load waterline
at stem head (3) Sheerstrake, see Notes 4 and 5:
(a) Forward of 0,075L from the F.P.: where > 0,7
where £ 0,7
(b) Between 0,075L and 0,2L from the F.P.,
see Note 7
(c) Aft of 0,2L from the F.P., see Note 7
T D T D
t =
(
6,5 + 0,033L)
(
see Note 1)
As (1)(a) or the taper thickness, whichever is the greater
The taper thickness (see Note 2)
k s1 sb
t =
(
6,5 + 0,033L)
(
see Note 1)
As (2)(a) or the taper thickness, whichever is the greater
The taper thickness, see Note 2
k s1 sb
As (2)(a) for side shell As (4) for a forecastle
As (3)(a) or as determined from Table 3.2.1 in Chapter 3
The taper thickness, see Note 2
Symbols
L, B, D, T, s, k as defined in 1.4.1
s1 = s, but to be taken as not less than sb
sb = standard frame spacing, in mm, as follows:
A1= cross-sectional area of bar stem below load waterline, in cm2
A2= cross-sectional area of bar stem at stem head, in cm2
L2 = L, but need not be taken greater than 215 m Region
Forward of 0,05L from the F.P.
Between 0,05L and 0,2L from the F.P.
Between 0,2L and 0,25L from the F.P. Bottom shell sb
(
470 +)
or 600*(
470 +)
or 700*(
510 +)
Side shell sb(
470 +)
or 600*(
470 +)
or 700* *whichever is the lesserL 0,6 L 0,6 L2 0,6 L 0,6 L 0,6 t =