Section 2 Scantlings of erections other than forecastles

2.1.1 The thickness, t, of plating of the fronts, sides and aft ends of all erections, other than the sides of superstructures where these are an extension of the side shell, is to be not less than:

but in no case is the thickness to be less than:

1. for the lowest tier:

   t

   =

2. for the upper tiers:

   t

   =

   but not less than 5,0 mm

2.1.2 The thickness of sides of poops and bridges is to be as required by Pt 3, Ch 6, 3 Shell envelope plating or Pt 4, Ch 1, 5 Shell envelope plating, as appropriate.

2.2.1 The modulus of stiffeners, Z, on front, side and end bulkheads of all erections, other than sides of superstructures, is to be not less than:

2.2.2 The section modulus of side frames of poops and bridges is to comply with the requirements of Pt 3, Ch 6, 4 Shell envelope framing or Pt 4, Ch 1, 6 Shell envelope framing, as appropriate.

2.2.3 The end connections of stiffeners are to be as given in Table 8.2.1 Stiffener end connections.

2.3.1 The requirements of Pt 3, Ch 8, 2.3 Deck plating need not apply to effective superstructure decks of passenger ships and ferries where direct calculations have been carried out in accordance with the SDA procedure relevant to the ship type.

2.3.2 The thickness of erection deck plating is to be not less than that required by Table 8.2.2 Thickness of deck plating.

2.3.3 When decks are fitted with approved sheathing, the thicknesses derived from Table 8.2.2 Thickness of deck plating may be reduced by 10 per cent for a 50 mm sheathing thickness, or 5 per cent for 25,5 mm, with intermediate values in proportion. The steel deck is to be coated with a suitable material in order to prevent corrosive action, and the sheathing or composition is to be effectively secured to the deck, see also Pt 6, Ch 4 Fire Protection, Detection and Extinction Requirements. Inside deckhouses the thickness may be reduced by a further 10 per cent.

2.4.1 The requirements of Pt 3, Ch 8, 2.4 Deck longitudinals and beams need not apply to effective superstructure decks of passenger ships and ferries where direct calculations have been carried out in accordance with the SDA procedure relevant to the ship type.

2.4.2 The section modulus of superstructure deck longitudinals and beams is to be in accordance with the requirements for location (2) in Table 1.4.4 Cargo and accommodation deck longitudinals and location (3) in Table 1.4.5 Strength/weather, cargo and accommodation deck beams in Pt 4, Ch 1 General Cargo Ships, using design heads not less than those specified in Table 3.5.1 in Chapter 3 for superstructure decks.

2.4.3 Transverse deck beams in deckhouses and deck longitudinals other than as in Pt 3, Ch 8, 2.7 Erections contributing to hull strength are to have a section modulus, Z, not less than:

and the value of h ₂, the load head, is to be taken as not less than:

2.5.1 The section modulus of deck girders and transverses is to be in accordance with the requirements for location (1) in Table 1.4.6 Deck girders, transverses and hatch beams inPt 4, Ch 1 General Cargo Ships, using design heads not less than those specified in Table 3.5.1 Design heads and permissible cargo loadings for superstructure decks.

2.6.1 Web frames or partial bulkheads are to be fitted within poops and bridges that have large deckhouses or other erections above.

2.6.2 Web frames or equivalent strengthening are also to be arranged to support the sides and ends of large deckhouses.

2.6.3 These web frames should be spaced about 9 m apart and are to be arranged, where practicable, in line with watertight bulkheads below. Webs are also to be arranged in way of large openings, boats, davits and other points of high loading.

2.6.4 Arrangements are to be made to minimise the effect of discontinuities in erections. All openings cut in the sides are to be substantially framed and have well rounded corners. Continuous coamings or girders are to be fitted below and above doors and similar openings. House tops are to be strengthened in way of davits. Special care is to be taken to minimise the size and number of openings in the side bulkheads in the region of the ends of erections within 0,5L amidships. Account is to be taken of the high vertical shear loading which can occur in these areas.

2.6.5 Adequate support under the ends of erections is to be provided in the form of webs, pillars, diaphragms or bulkheads in conjunction with reinforced deck beams. At the corners of houses and in way of supporting structures, attention is to be given to the connection to the deck, and inserts or equivalent arrangements are generally to be fitted especially for erections that are effective in resisting vertical hull girder bending as defined in Pt 3, Ch 3, 4.2 Collision bulkhead.

2.6.6 The side plating of bridges having a length of 0,15L or greater is to be increased in thickness by 25 per cent at the ends of the structure, and is to be tapered into the upper deck sheerstrake. This plating is to be efficiently stiffened at the upper edge and supported by web plates not more than 1,5 m from the end bulkhead. Proposals for alternative arrangements, including the use of higher tensile steel, will be individually considered.

2.7.1 Where a long superstructure or deckhouse is fitted, extending at least 0,15L, the scantlings of the first tier deck plating and longitudinals may be required to be increased, see also Pt 3, Ch 3, 3.4 Calculation of hull section modulus and Pt 3, Ch 4, 2.3 Open type ships.

2.8.1 Where superstructures or deckhouses are of unusual design, the strength is to be not less than that required by this Chapter for a conventional design.