Section 4 Deck structure

4.1.1 Longitudinal framing is, in general, to be adopted outside line of openings. The arrangement of structure between hatches is to be such as to ensure continuity of the main deck structure to resist athwartship forces, and transverse stiffening is to be arranged. For and aft knuckles in cross deck strip plating between hatches should be arranged close to longitudinal girders or supported by brackets.

4.1.2 In the case of large bulk carriers with narrow deck strips between hatchways, or where it is the intention to load any two adjoining holds with adjacent holds fully empty for a sea-going condition or for bulk carriers to be classed `any hold may be empty', the cross deck scantlings will be specially considered.

4.1.3 The requirements of Pt 4, Ch 1, 4 Deck structure are to be applied, together with the requirements of this Section.

4.1.4 The Shipright FDA Procedure, Structural Detail Design Guide (SDDG), indicates recommended structural design configurations in critical areas, for the deck structure outside the line of openings and between hatches.

4.2.1 Where the difference between the thickness of plating inside and outside the line of main hatches exceeds 12 mm, a transitional plate of thickness equivalent to the mean of the adjacent plate thicknesses is to be fitted. The plate thickness outside the line of hatches is to be continued inboard between hatches beyond the end of the hatch corner curvature, to ensure that the chamfered plating is clear of the corner tangent point.

4.3.1 The following requirements apply to bulk carriers with vertically corrugated transverse bulkheads in cargo holds having one or more of the following characteristics:

1. B ≥ 40 m

2. ≥ 2,2

   b

   =

   breadth of deck opening

   w

   =

   width of cross deck strip

   B

   =

   moulded breadth of ship

3. A structural arrangement where the hatch side coaming and deck opening are arranged inboard of the topside tank.

4. All bulk carriers to be classed 100A1 bulk carrier, strengthened for heavy cargoes, any hold may be empty, ESP.

4.3.2 The corners of main cargo hatchways in the strength deck are to be rounded with a radius not less than of the breadth of the opening, with a maximum radius of 1000 mm.

4.3.3 Insert plates are to be fitted at the corners having a thickness not less than 25 per cent greater than the adjacent deck thickness outside the line of openings, with a minimum increase of 5 mm, see also Pt 4, Ch 7, 4.3 Main cargo hatchway openings 4.3.4.

The corner inserts are to be extended transversely into the cross deck plating for a minimum distance equal to 0,075b, where b, is the breadth of deck opening.

4.3.4 For the extreme corners of the end hatchways of the cargo region furthest from amidships the thickness of the corner insert plates is to be not less than 60 per cent greater than the adjacent deck thickness outside the line of openings.

4.4.1 For the scantlings of deck longitudinals and transverses in way of topside tanks, see Pt 4, Ch 7, 7.4 Shell and deck structure and Pt 4, Ch 7, 7.5 Primary supporting structure, respectively.