Section 7 Bottom strengthening for operating aground
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 4 Ship Structures (Ship Types) - Chapter 12 Dredging and Reclamation Craft - Section 7 Bottom strengthening for operating aground

Section 7 Bottom strengthening for operating aground

Parent topic: Chapter 12 Dredging and Reclamation Craft

7.1 Application

7.1.1 The scantlings of bottom structure are to comply with the requirements given in Table 12.7.1 Bottom strengthening for operating aground.

7.1.2 Unless otherwise specified by the Owner, it should be assumed that non-self-propelled dredging and reclamation craft are to operate aground.

Table 12.7.1 Bottom strengthening for operating aground

Item Requirement
The following requirements are to be applied to the bottom structure upon which the ship is likely to be supported whilst aground

(1) Bottom shell, keel and swim end plating

 Thickness to be increased by 20% over the minimum requirements of Pt 4, Ch 1, 5 Shell envelope plating, with a minimum of 8 mm

(2) Bottom longitudinals

 Scantlings as required by Table 12.5.1 Longitudinal stiffening(1) taking K 1 = 74 and c = 1,0

(3) Bilge longitudinals (where fitted)

 Scantlings to be the same as bottom longitudinals
  Transverse framing Longitudinal framing

(4) Primary stiffening in way of single bottoms, see Notes 1 and 2

(a) Floors to be fitted at every frame with vertical stiffeners spaced, in general, not more than 1,25 m apart

(a) The spacing of transverses or floors is, in general, not to exceed 2,5 m outboard of wells or 1,85 m elsewhere

(b) Side girders to be spaced not more than 2,2 m apart and intermediate 100 mm x 10 mm bulb plate longitudinals, or equivalent, fitted

(b) The panel size nearest the shell plating of web plates of transverses or floors is, in general, not to exceed 80t x 80t where t is the actual web thickness

(c) Side girders to be spaced not more than 2,2 m apart

(5) Primary stiffening in way of double bottoms, see Notes 1 and 2

(a) Plate floors are to be fitted at every frame with vertical stiffeners spaced, in general, not more than 1,25 m apart

(a) The spacing of plate floors is, in general, not to exceed 1,85 m

(b) Side girders to be spaced not more than 2,5 m apart and intermediate 100 mm x 10 mm bulb plate longitudinals, or equivalent, fitted

(b) Side girders to be spaced not more than 2,5 m apart

(c) Where the span of floors between a hopper space and the ship's side exceeds 3,75 m, a longitudinal girder is to be fitted

Note 1. The scantlings of floors, girders and transverses are to be determined in accordance with the requirements of Pt 4, Ch 12, 6 Bottom structure.

Note 2. The number and size of holes in floors, girder and transverses are to be kept to a minimum, see Pt 4, Ch 1, 8 Double bottom structure.

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