Section 5 Platings

501. Definitions

1. Craft side is ranged as defined below :

(1) Upper bound : the upper deck, including long and short superstructure sides.

(2) Lower bound : the top of the bottom structure.

(3) Forward bound : the stem.

(4) Aft bound : the stern including transom.

2. The upper bound of the slamming area is at the turn of bilge or chine knuckles, and in cases no knuckles case, the upper bound shall be reached at 1.25 m above keel.

3. The definitions of symbols used in this chapter, unless specified otherwise, are to be in accordance with the following :

: thickness of plating (mm )

section modulus of stiffeners (cm )

: stiffener spacing measured along the plating (m )

basic stiffener spacing (m ), as defined

:

m

= 0.76 (m ), for watertight bulkheads, cargo hold bulkheads, superstructure and deck- house bulkheads

: stiffener span (m ) measured along the top flange of the member

: allowable bending stress (N mm

or

: design pressure (kN m ) as defined in Ch 2.

: midship section modulus (cm ), as built at deck or bottom respectively

: midship section modulus (cm ), as defined in 401.

: correction factor for aspect ratio of plating field, see Table 3.3.1.

: radius of curvature (m )

: material factor in Table 3.3.2, as defined in Table 2.1.5. of Pt 2, Ch the Classification of Steel Ships.

1. of Rules for

Table 3.3.1 Correction Factor Table 3.3.2 Material Factor ( )

502. Keel plating

1. The keel plating is to extend over the complete length of the craft. The breadth is not to be less than that obtained from the following formula :

mm

2. The thickness of keel plating is not to be less than the values according to the formula below. The thickness is, in no case, to be less than that of the adjacent bottom plating.

mm

is not to be taken less than 0.5 or greater than

503. Bottom and bilge plating

1. The thickness of bottom and bilge plating is not to be less than formula :

that obtained from the following

or

mm

The following extended formula for thickness of plating exposed when relevant.

to lateral pressure may be used

mm

and : as defined in

sea pressure or internal tank pressure, as defined in Ch 2, 304 or 305.

: static pressure equivalent to slamming, as defined in Ch 2, 301.

allowable stress, as defined in varied linearly.

Table 3.3.3. Between specified regions the s-value may be

Table 3.3.3 Allowable Stress (

2. The thickness of bottom and bilge plating is not to be less than that obtained from the following formula :

min

is not to be taken less than 0.5 or greater than 1.0.

3. The thickness of bilge plating is not to be less than that of the adjacent bottom and side platings, whichever is the greater.

4. Plating in way of rudder bearings, shaft brackets, etc. may have to be increased to 2 times that of the adjacent platings.

504. Side plating

1. The thickness of side plating is not to be less than that obtained from the following formula :

or

mm

The following extended formula for thickness of plating exposed to lateral pressure when relevant.

may be used

or

mm

and : as defined in

:

as defined in 503. Par 1.

as defined in Ch 2, 302 or 303.

allowable stress, as defined in Table 3.3.4

2. The thickness of side plating is not to be less than formula defined in 503. Par 2.

Table 3.3.4 Allowable Stress of Side Plating

505. Sheer strake at strength deck

1. The breadth of sheer strake is not to be less than that obtained from the following formula :

mm

2. The thickness of lowing formula :

monohull craft with L > 50m is not to be less than that obtained from the fol-

mm

: thickness of side plating, defined in 504.

: thickness of strength deck plating, defined in 506. is not to be taken less than .

3. If the end bulkhead of a superstructure is located within 0.5 amidships, the side plating should be given a smooth transition to the sheer strake below.

(1) The range for the sheer strake with increase thickness

m :

≥ m : 2.5 m

(2) The increase thickness of sheer strake

m : (1 + 0.005 ) times of thickness, defined in previous Par

≥ m : 1.3 times of thickness, defined in previous Par

506. Strength deck plating

1. The thickness of strength mula :

deck plating is not to be less than that obtained from the following for-

mm

: defined in Table 3.3.5 considering that deck position and is not to be taken values

Table 3.3.5 Minimum Thickness (

and Stiffener Spacing Ratio (

2. If the end bulkhead of a long superstructure is located within 0.5 amidship, the stringer

is to be increased in thickness for a length of bulkhead. The increase in thickness is to be 20 %.

3. If hatch opening corners of streamlined shape are strength deck at hatch corners is to be increased by

3 m on each side of the superstructure end

not adopted, the thickness of deck plating in 25 %.

507. Plating of deck below or above strength deck

1. The thickness of deck plating below or above strength deck is not to be less than following for- mula, and the deep tank boundary deck plating is not to be less than the thickness, defined in 508.

mm

: defined in Table 3.3.6 considering that deck position and is not to be taken values

Table 3.3.6 Minimum Thickness (

and Stiffener Spacing Ratio (

508. Bulkhead plating

1. The thickness of bulkhead or tank boundary bulkhead is not to be less than that obtained from the following formula :

mm

The following extended formula for thickness of plating may be used when relevant.

mm

and : as defined in 501.

: design load, defined in Ch 2, 305.

: allowable stress, defined in Table

Table 3.3.7 Allowable Stresses of Bulkheads

2. The thickness of the tank boundary bulkhead is ing formula :

not to be less than that obtained from the follow-

mm

is not to be taken less than 0.5 or greater than 1.0.

3. The thickness of other bulkhead is not to be less than that obtained from the following formula.

However the thickness is not to be less than 3.0 mm .

mm

4. For platings in afterpeak bulkhead in way of sterntube, increased thickness or doubling may be required.

509. End bulkheads of superstructures and deckhouses, and exposed sides in deck- houses

1. The thickness of end bulkheads of superstructures and deckhouses and exposed sides in deckhouse bulkhead is not to be less than that obtained from the following formula :

mm

: design load, defined in Ch 2, 307.

2. The thickness of end bulkheads of superstructure and deckhouse is not to be less than that obtained

from the following formula :

(1) For the lowest tier

mm

is not to be taken less than

(2) For higher tiers : mm

is not to be taken less than 2.5 mm

510. Machinery casings

The thickness of machinery casings protected by closed superstructure and deckhouse is not to be less than the following formula. However, thickness is not to be less than 4.0 mm .

(1) Machinery casings in cargo holds : mm

(2) Machinery casings in accommodation area : mm

511. Bulwark plating

1. The thickness of bulwark

(1) The thickness of bulwark plating is not to be less than required for side plating in a super- structure in the same position if the height of the bulwarks is 1.8 m .

(2) If the height of bulwark is 1 m or less, the thickness need not be greater than that obtained

form the following formula :

mm

maximum : 6 mm , minimum : 3 mm

(3) For intermediate heights, the thickness of the bulwark may be found by interpolation.

2. Long bulwarks are to have expansion joints within 0.6 amidship.

3. Where bulwarks are on exposed decks form wells, ample provision is to be made for freeing the decks of water.

4. Bulwarks for ships with > 50 m are in general not to be welded to the top of the sheer strake within 0.6 amidship. Such weld connections may, however, be accepted upon special consid- eration of design, thickness and material grade.