Section 7 Bottom strengthening for loading and unloading aground
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 3 Ship Structures (General) - Chapter 9 Special Features - Section 7 Bottom strengthening for loading and unloading aground

Section 7 Bottom strengthening for loading and unloading aground

Parent topic: Chapter 9 Special Features

7.1 Application

7.1.1 Where a ship of length, L, less than 90 m has the bottom structure additionally strengthened for loading and unloading aground in accordance with Table 9.7.1 Bottom strengthening for loading and unloading aground, it will be eligible for the special features notation `bottom strengthened for loading and unloading aground'. Ships of length, L, 90 m or more intended for this service will receive individual consideration.

7.1.2 For dredgers intended to operate aground, the requirements of Pt 4, Ch 12 Dredging and Reclamation Craft are to be applied.

Table 9.7.1 Bottom strengthening for loading and unloading 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 and keel plating

 Thickness to be increased by 20% over the minimum requirements given in Part 4 for the particular type of ship with a minimum of 8 mm
  For dry cargo ships, as required in way of double bottoms, see item (3)

(2) Bottom longitudinals in way of single bottoms

 For oil tankers, scantlings as required by Table 9.5.1 Values of F1 in Pt 4, Ch 9 in taking c 1 = 1,0

(3) Bottom longitudinals in way of double bottoms, see Note 1

For dry cargo ships, scantlings as required by Table 1.6.1 Shell framing (longitudinal) in Pt 4, Ch 1 in taking c 1 = 1,0

(4) Bilge longitudinals
(where fitted)

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

(5) Primary stiffening in way of single bottoms, see Notes 2 and 3

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

(b) One side girder is to be fitted on each side of the centreline in addition to the requirements ofPt 4, Ch 1, 7 Single bottom structure and intermediate 150 x 10 bulb plate longitudinals or equivalent fitted

(a) The arrangements and scantlings will receive individual consideration depending on the structural arrangements of the particular ship type

(b) The spacing of transverse or floors is, in general, not to exceed 1,85 m

(6) Primary stiffening in way of double bottoms, see Notes 1, 2 and 3

(a) Plate floors are to be fitted at every frame and vertical stiffening arranged to give panel widths, in general, not exceeding 1,25 m

One side girder is to be fitted on each side of the centreline in addition to the requirements of Pt 4, Ch 1, 8 Double bottom structure and intermediate 150 x 10 bulb plate longitudinals or equivalent fitted

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

(b) One side girder is to be fitted on each side of the centreline in addition to the requirements of Pt 4, Ch 1, 8 Double bottom structure

Note 1. For oil tankers, to be specially considered.

Note 2. The scantlings of floors, girders and transverses are to be determined from Pt 4 Ship Structures (Ship Types), for the particular ship type.

Note 3. The number and sizes of holes in floors, girders and transverses are to be kept to a minimum; see Pt 4, Ch 1, 8 Double bottom structure and Pt 4, Ch 9, 6 Inner hull, inner bottom and longitudinal oiltight bulkheads.

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