Section 2 Minimum thickness requirements
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Special Service Craft, July 2022 - Part 7 Hull Construction in Aluminium - Chapter 3 Scantling Determination for Mono-Hull Craft - Section 2 Minimum thickness requirements

Section 2 Minimum thickness requirements

2.1 General

2.1.1 The thickness of plating and stiffeners determined from the Rule scantling requirements is in no case to be less than that given in Table 3.2.1 Minimum thickness requirements for the craft type.

2.1.2 In addition, where plating contributes to the global strength of the craft, the thickness is to be not less than that required to satisfy the global strength requirements detailed in Pt 7, Ch 6 Hull Girder Strength.

2.2 Corrosion margin

2.2.1 The minimum thicknesses given in Table 3.2.1 Minimum thickness requirements are based on the assumption that there is negligible loss in strength by corrosion. Where this is not the case the minimum thickness will be specially considered.

Table 3.2.1 Minimum thickness requirements

Item Minimum thickness (mm)
Mono-hull Hydrofoil Rigid inflatable boat (RIB)
Shell envelope      

Bottom shell plating

Side shell plating

Single bottom structure      

Centre girder web

Floor webs

Side girder webs

Double bottom structure      

Centre girder

     

(1)Within 0,4L R amidships

(2) Outside 0,4L R amidships

Floors and side girders

Inner bottom plating

Bulkheads      

Watertight bulkhead plating

Deep tank bulkhead plating

Deck plating and stiffeners      

Strength/Main deck plating

Lower deck/Inside deckhouse

Superstructures and deckhouses      

Superstructure side plating

Deckhouse front 1st tier

Deckhouse front upper tiers

Deckhouse aft

Pillars      

Wall thickness of tubular pillars

Wall thickness of rectangular pillars

Symbols
ω =

= service type correction factor as determined from Table 3.2.2 Service type correction factors (ω)

k m =

= 385/(σA + σu)

σA =

= specified minimum yield stress or 0,2% proof stress of the alloy in unwelded condition, in N/mm2

σu =

= specified minimum ultimate tensile strength of the alloy in unwelded condition, in N/mm2

b p =

= minimum breadth of cross section of hollow rectangular pillar, in mm

d p =

= outside diameter of tubular pillar, in mm

L R is as defined in Pt 7, Ch 3, 1.5 Symbols and definitions 1.5.1

2.3 Impact considerations

2.3.1 Due consideration is to be given to the scantlings of all structure which may be subject to local impact loadings. Impact testing may be required to be carried out at the discretion of LR to demonstrate the suitability of the proposed scantlings for a particular application.

2.4 Sheathing

2.4.1 Areas of shell and deck which are subject to additional wear by abrasion e.g. passenger routes, working areas of fishing craft, forefoot region etc, are to suitably protected by local reinforcement or sheathing. This sheathing may be of timber, rubber, steel, additional layers of reinforcement, etc. as appropriate. Details of such sheathing and the method of attachment are to be submitted for consideration.

2.4.2 The attachment of sheathing by mechanical means such as bolting or other methods is not to impair the watertight integrity of the craft. Through bolting of the hull is to be kept to a minimum and avoided where practicable. The design arrangements in way of any through bolting are to be such that damage to the sheathing will not impair the watertight integrity of the hull.

2.5 Operation in ice

2.5.1 The minimum plating thickness of craft intended for operation in ice conditions is to comply with Pt 7, Ch 5, 7 Strengthening requirements for navigation in ice conditions.

Table 3.2.2 Service type correction factors (ω)

Service type notation ω
Cargo 1,1
Passenger 1,0
Patrol 1,0
Pilot 1,1
Yacht 1,0
Workboat MFV 1,2

Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.