Section 2 Decks

201. General

1. Watertightness of the decks

Except specially permitted by this Society, the decks are to be of watertight structure.

2. Compensation of deck openings

Hatchways and other openings on decks are to have well rounded corners and to be compensated with appropriate means as necessary.

3. Local compensation

(1) The cofferdam is to be installed or to be strengthened with appropriate means in way of the ladder well

(2) The places where heavy dredging equipment are installed or local stresses are occurred are to be strengthened appropriately.

202. Deck loads

1. The value

Y of the deck loads

The value Y

of deck loads on deck, deck beam, girder, pillar and truss is to be obtained from one

of the followings;

(1) h is to be equivalent to the standards given by 7 times the tween deck height at side of the space(m), or 7 times the height from the deck concerned to the upper edge of hatch coaming

of the above deck (m). However,

h may be specified as the maximum design cargo weight per

unit area of deck (kN/m2). In this case, the value of loading height of cargo.

h is to be determined by considering the

(2) Deck loads Y (kN/m2) on non-exposed decks and platforms are to be defined by the designer

without being less than 3.0 (kN/m2) for accommodation decks and 10.0 (kN/m2) for other decks and platforms.

(3) The deck loads of the exposed deck are to be obtained from the following formula;

ŴFẄX GŻ F (kNĤmË)

Ŵ and Ẅ : value obtained from Table 4.1

However, Y of Item II need not to exceed the value of Item I.

X : the value obtained from the following formula

Ä < 90 m : 0.067 Ä, 90 m ≦ Ä ≦ 150 m : 0.051 Ä

Ch 4

Table 4.1 Value, Ŵ and Ẅ

Ż : the vertical distance from the load line to the exposed deck at the ship's side in ac- cordance with the followings;

(A) For decks located in between fore end and 0.15 Ä , it is to be measured from the fore end.

(B) For decks located in between 0.15 Ä and 0.3 Ä from the fore end, it is to be measured at the point of 0.15 Ä from the fore end.

(C) For decks located in between the aft end and 0.2 Ä from the aft end, it is to be measured from the aft end.

(D) For decks other than those mentioned in (A), middle of Ä.

(B) and (C), it is to be measured from the

(4) Regardless of the requirements in the above

formula given in Table 4.2;

(3), Y

is not to be less than that obtained from the

Table 4.2 Minimum value of h

Ch 4

203. Effective sectional area of strength deck

1. Definition

The effective sectional area of strength deck is the sectional area, on each side of the ship's centre line such as strength deck, longitudinal beam and longitudinal girder etc. that are longitudinal or deemed to be longitudinal, extending not less than 0.5 Ä at amidships.

2. Effective sectional area of strength deck

(1) The effective sectional area of strength deck at the midship part is to be so determined as to be not less than the value that fulfills the section modulus of athwartship section calculated from the requirement in Ch 3.

(2) Beyond the midship part toward the fore end and aft end, the effective sectional area may be gradually reduced. However, at 0.15 Ä from the fore and aft end, it is not to be less than 50 %

of the effective sectional area at the midship part.

204. Thickness of the strength deck

1. Thickness of the strength deck

The thickness of the strength deck is not to be less than that obtained from the followings. However, within the superstructure or steel deckhouse, it may be reduced from the thickness ob- tained from the formula, by 1 mm .

(1) At amidships, the thickness of deck plating outside the line of hatchway opening is to not to be less than that obtained from the followings;

Decks of longitudinal framing system Decks of transverse framing system

: Ź G ËĦĖĒ ÅĬJY Ğ ËĦÈ (mm )

: Ź G ËĦÈĖ ÅĬJY Ğ ËĦÈ (mm )

Å : spacing of longitudinal or transverse beam (m )

Y : the value obtained from Table 4.1

(2) The thickness of the deck plating other than (1) and other deck plating is not to be less than that obtained from the following formula;

Ź G ËĦËÈ ÅĬJY Ğ ËĦÈ (mm )

Å and Y

: as required in the above (1)

2. Deck plating forming the top of tanks

The thickness of deck plating forming the top of tanks is not to be less than the thickness as re- quired in Ch 7, Sec 3, when the spacing of beams is regarded as the spacing of stiffeners.