All timber used for grain fittings shall be of good sound quality and of a type and grade which has been proved to be satisfactory for this purpose. The actual finished dimensions of the timber shall be in accordance with the dimensions hereinafter specified in this Part. Plywood of an exterior type bonded with waterproof glue and fitted so that the direction of the grain in the face plies is perpendicular to the supporting uprights or binder may be used provided that its strength is equivalent to that of solid timber of the appropriate scantlings.

When calculating the dimensions of divisions loaded on one side, using the Tables in paragraphs (a) and (b) and Subsection (C) of this Section, the following working stresses should be adopted:

For divisions of steel                                2 000 kg per square cm

For divisions of wood                                160 kg per square cm

Materials other than wood or steel may be approved for such divisions provided that proper regard has been paid to their mechanical properties.

Where uprights, binders or any other strength members are formed by two separate sections, one fitted on each side of a division and interconnected by through bolts at adequate spacing, the effective section modules shall be taken as the sum of the two moduli of the separate sections.

Where divisions do not extend to the full depth of the hold such divisions and their uprights shall be supported or stayed so as to be as efficient as those which do extend to the full depth of the hold.

(B)        DIVISIONS LOADED ON BOTH SIDES

If thicknesses greater than these are provided the maximum unsupported span will vary directly with the increase in thickness.

Divisions formed by using materials other than wood shall have a strength equivalent to the shifting boards required in paragraph (a) of this subsection.

Where—

W =        section modulus in cm3

a =        horizontal span between uprights in metres.

The Section modulus per metre span W1 shall not be less than that given by the formula:

Where—

h1 is the vertical unsupported span in metres and shall be taken as the maximum value of the distance between any two adjacent stays or between the stay or either end of the upright. Where this distance is less than 2,4 metres the respective modulus shall be calculated as if the actual value was 2,4 metres.

Shores of 7 metres or more in length shall be securely bridged at approximately mid-length (iii) When the horizontal distance between the uprights differs significantly from 4 metres, the moments of inertia of the shores may be changed in direct proportion.

Where stays are used to support divisions loaded on both sides, they shall be fitted horizontally or as near thereto as practicable, well secured at each end and formed of steempune sizes of the wire rope shall be determined assuming that the divisions and upright which the stay supports are uniformly loaded at 500 kg/m2. The working load so assumed in the stay shall not exceed one-third of its breaking load.

The load in kg per metre length of the division shall be taken to be as follows:

TABLE I

B (m)

For other values of h or B the loads shall be determined by linear interpolation or extrapolation as necessary.

The load in kg per metre length of the division shall be taken to be as follows:

TABLE II

L (m)

For other values of h or L the loads shall be determined by linear interpolation or extrapolation as necessary.

The total load per unit length of divisions shown in the Tables I and II above may, if considered necessary, be assumed to have a trapezoidal distribution with height. In such cases, the reaction loads at the upper and lower ends of a vertical member or upright are not equal. The reaction loads at the upper end expressed as percentages of the total load supported by the vertical member or upright shall be taken to be those shown in Tables III and IV below.

TABLE III

LONGITUDINAL DIVISIONS LOADED ON ONE SIDE ONLY

Bearing Reaction at the Upper End of Upright as Percentage of Load (Table I)

B (m)

For other values of h or L the loads shall be determined by linear interpolation or extrapolation as necessary.

B =        transverse extent of the bulk grain in metres.

TABLE IV

TRANSVERSE DIVISIONS LOADED ON ONE SIDE ONLY

Bearing Reaction at the Upper End of Upright as Percentage of Load (Table II)

L (m)

For other values of h or L the reaction loads shall be determined by linear interpolation or extrapolation as necessary.

The strength of the end connections of such vertical members or uprights may be calculated on the basis of the maximum load likely to be imposed at either end. These loads are as follows:

Longitudinal Divisions:

Maximum load at the top                50 per cent of the appropriate total load from Table I

Maximum load at the bottom                55 per cent of the appropriate total load from Table I

Transverse Divisions:

Maximum load at the top                45 per cent of the appropriate total load from Table II

Maximum load at the bottom                45 per cent of the appropriate total load from Table II

The thickness of horizontal wooden boards may also be determined having regard to the vertical distribution of the loading represented by Tables III and IV above and in such cases

Where—

When the vertical distribution of the loading is assumed to be uniform, i.e. rectangular, k shall be taken as equal to 1.0. For a trapezoidal distribution

Where—

R is the upper end bearing reaction taken from Table III or IV.

The sizes of stays and shores shall be so determined that the loads derived from Tables I and II in the preceding paragraphs (a) and (b) shall not exceed one-third of the breaking loads.

When a saucer is used to reduce the heeling moments in a “filled compartment”, its depth, measured from the bottom of the saucer to the deck line, shall be as follows:

For ships with a moulded breadth of up to 9,1 metres, not less than 1,2 metres. For ships with a moulded breadth of 18,3 metres or more, not less than 1,8 metres.

For ships with a moulded breadth between 9,1 metres and 18,3 metres, the minimum depth of the saucer shall be calculated by interpolation.

The top (mouth) of the saucer shall be formed by the underdeck structure in the way of the hatchway, i.e. hatchside girders or coamings and hatchend beams. The saucer and hatchway above shall be completely filled with bagged grain or other suitable cargo laid down on a separation cloth or its equivalent and stowed tightly against adjacent structures and the portable hatchway beams if the latter are in place.

As an alternative to filling the saucer with bagged grain or other suitable cargo a bundle of bulk grain may be used provided that—

Athwartship lashings acceptable to the Administration shall be placed inside the saucer formed in the bulk grain at intervals of not more than 2,4 metres. These lashings shall be of sufficient length to permit being drawn up tight and secured at the top of the saucer; dunnage not less than 25 mm in thickness or other suitable material of equal strength and between 150 to 300 mm in width shall be placed fore and aft over these lashings to prevent the cutting or chafing of the material which shall be placed thereon to line the saucer;

If there is no bulk grain or other cargo above a “filled compartment” the hatch covers shall be secured in an approved manner having regard to the weight and permanent arrangements provided for securing such covers.

The documents of authorization issued under Regulation 10 of this Chapter shall include reference to the manner of securing considered necessary by the Administration issuing such documents.