Section 4 Deck structure

4.1.1 The strength deck, outside the line of openings, is to be longitudinally framed throughout the cargo hold region. The strength deck, inside the line of openings, may also be longitudinally framed.

4.1.2 The requirements of Pt 4, Ch 1, 4 Deck structure of the Rules for Ships are to be applied, together with the additional requirements of this Section.

4.2.1 The thickness of the strength deck plating, outside the line of openings, is to be maintained as per Pt 3, Ch 4, 7.1 Application 7.1.2 of the Rules for Ships, and may be tapered to Rule thickness at ends.

4.2.2 The thickness of the strength deck plating, inside the line of openings and clear of the screen bulkhead under, is to be taken as:

s is spacing of secondary stiffeners, in mm.

4.2.3 The strength deck plate thickness outside the line of openings, is to be continued inboard between hatches, 100 mm minimum, beyond the inboard end of the hatch corner curvature to ensure that the chamfered plating is clear of the corner tangent point. See Figure 4.4.1 Corners of main cargo hatchways.

4.2.4 The thickness of the underdeck passage tunnel, where fitted, at the upper side shell stringer level is to be not less than the greater of Table 1.4.2 Lower deck plating of the Rules and Regulations for the Classification of Ships, July 2022 or 9,5 mm in thickness.

4.3.1 The scantlings of the strength deck longitudinals are to be maintained as per Pt 3, Ch 4, 7.1 Application 7.1.2 of the Rules for Ships and may be tapered to Rule scantlings at ends.

4.3.2 The scantlings of the strength deck longitudinals are to comply with the requirements of Table 1.4.3 Strength/weather deck longitudinals of the Rules for Ships.

4.3.3 The scantlings of the strength deck beams, are to comply with the requirements of Table 1.4.5 Strength/weather, cargo and accommodation deck beams of the Rules for Ships.

4.3.4 The deck longitudinals outside the line of openings are to be continuous through the transverse structure, throughout the cargo hold region.

4.3.5 The deck transverse arch beam under and between the hatches is to comply with the requirements of Table 1.4.6 Deck girders, transverses and hatch beams of the Rules for Ships.

4.4.1 The corners of main cargo hatchways in the strength deck are to be elliptical or rounded. The hatch corner radii are to be 300 mm min. and the elliptical corners 600 mm min. x 300 mm min. with the major axis in a fore and aft direction, see Figure 4.4.1 Corners of main cargo hatchways.

4.4.2 Insert plates in way of the hatch corners are not generally required.

4.4.3 Where openings in the strength deck plating are arranged, outside the line of openings, the requirements of Pt 4, Ch 1, 4.5 Deck openings 4.5.4 of the Rules for Ships, will apply, except that the longitudinal extent required for compensation is increased, see Ch 4, 3.4 Hull bending strength 3.4.8.