Hull Structure and Arrangenment for the Classification of Cargo Ships Less Than 65 and Non Cargo...

8/9/2019 Hull Structure and Arrangenment for the Classification of Cargo Ships Less Than 65 and Non Cargo Ships Less Than 90 m - 600NR_2014-07

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Hull Structure and Arrangementfor the Classification of

Cargo Ships less than 65 m andNon Cargo Ships less than 90 m

July 2014

Rule NoteNR 600 DT R00 E

Marine & Offshore Division92571 Neuill y su r Seine Cedex – France

Tel: + 33 (0)1 55 24 70 00 – Fax: + 33 (0)1 55 24 70 25Marine website: http://www.veristar.comEmail: [email protected] Bureau Veritas - All right s reserved


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ARTICLE 11.1. - BUREAU VERITAS is a Society the purpose of whose Marine & Offshore Division (the "Society") isthe classification (" Classification ") of any ship or vessel or offshore unit or structure of any type or part of it or system therein collectively hereinafter referred to as a "Unit" whether linked to shore, river bed or seabed or not, whether operated or located at sea or in inland waters or partly on land, including submarines,hovercrafts, drilling rigs, offshore installations of any type and of any purpose, their related and ancillaryequipment, subsea or not, such as well head and pipelines, mooring legs and mooring points or otherwiseas decided by the Society.The Society:• "prepares and publishes Rules for classification, Guidance Notes and other documents (" Rules ");• "issues Certificates, Attestations and Reports following its interventions (" Certificates ");• "publishes Registers.1.2. - The Society also participates in the application of National and International Regulations or Stand-ards, in particular by delegation from different Governments. Those activities are hereafter collectively re-ferred to as " Certification ".1.3. - The Society can also provide services related to Classification and Certification such as ship andcompany safety management certification; ship and port security certification, training activities; all activi-ties and duties incidental thereto such as documentation on any supporting means, software, instrumen-tation, measurements, tests and trials on board.1.4. - The interventions mentioned in 1.1., 1.2. and 1.3. are referred to as " Services ". The party and/or itsrepresentative requesting the services is hereinafter referred to as the " Client ".The Services are pre-pared and carried out on the assumption that the Clients are aware of the International Maritimeand/or Offshore Industry (the "Industry") practices.1.5. - The Society is neither and may not be considered as an Underwriter, Broker in ship's sale or char-tering, Expert in Unit's valuation, Consulting Engineer, Controller, Naval Architect, Manufacturer, Ship-builder, Repair yard, Charterer or Shipowner who are not relieved of any of their expressed or impliedobligations by the interventions of the Society.ARTICLE 22.1. - Classification is the appraisement given by the Society for its Client, at a certain date, following sur-veys by its Surveyors along the lines specified in Articles 3 and 4 hereafter on the level of compliance of a Unit to its Rules or part of them. This appraisement is represented by a class entered on the Certificatesand periodically transcribed in the Society's Register.2.2. - Certification is carried out by the Society along the same lines as set out in Articles 3 and 4 hereafter and with reference to the applicable National and International Regulations or Standards.2.3. - It is incumbent upon the Client to maintain the condition of the Unit after surveys, to presentthe Unit for surveys and to inform the Society without delay of circumstances which may a ffect thegiven appraisement or cause to modify its scope.2.4. - The Client is to give to the Society all access and information necessary for the safe and efficientperformance of the requested Services. The Client is the sole responsible for the conditions of presenta-tion of the Unit for tests, trials and surveys and the conditions under which tests and trials are carried out.ARTICLE 33.1. - The Rules, procedures and instructions of the Society take into account at the date of their preparation the state of currently available and proven technical knowledge of the Industry. Theyare a collection of minimum requirements but not a standard or a code of construction neither aguide for maintenance, a safety handbook or a guide of professional practices, all of which areassumed to be known in detail and carefully followed at all times by the Client.Committees consisting of personalities from the Industry contribute to the development of those docu-ments.3.2. - The Society only is qualified to apply its Rules and to interpret them. Any reference to themhas no effect unless it involves the Society's intervention.3.3. - The Services of the Society are carried out by professional Surveyors according to the applicableRules and to the Code of Ethics of the Society. Surveyors have authority to decide locally on matters re-lated to classification and certification of the Units, unless the Rules provide otherwise.3.4. -The operations of the Society in providing its Services are exclusively conducted by way of ran-dom inspections and do not in any circumstances involve monitoring or exhaustive verification.

ARTICLE 44.1. - The Society, acting by reference to its Rules:• "reviews the construction arrangements of the Units as shown on the documents presented by the Cli-

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met.The Client is to inform the Society without delay of circumstances which may cause the date or theextent of the surveys to be changed.ARTICLE 55.1. -The Society acts as a provider of services. This cannot be construed as an obligation bearingon the Society to obtain a result or as a warranty.5.2. - The certificates issued by the Society pursuant to 5.1. here above are a statement on the levelof compliance of the Unit to its Rules or to the documents of reference for the Services provided for.In particular, the Society does not engage in any work relating to the design, building, productionor repair checks, neither in the operation of the Units or in their trade, neither in any advisory serv-ices, and cannot be held liable on those accounts. Its certificates cannot be construed as an im-plied or express warranty of safety, fitness for the purpose, seaworthiness of the Unit or of its valuefor sale, insurance or chartering .5.3. - The Society does not declare the acceptance or commissioning of a Unit, nor of its construc-tion in conformity with its design, that being the exclusive responsibility of its owner or builder. 5.4. - The Services of the Society cannot create any obligation bearing on the Society or constitute anywarranty of proper operation, beyond any representation set forth in the Rules, of any Unit, equipment or machinery, computer software of any sort or other comparable concepts that has been subject to any sur-vey by the Society.

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can be handed over to another Classification Society, where appropriate, in case of the Unit's transferof class;

• "the data relative to the evolution of the Register, to the class suspension and to the survey status ofthe Units, as well as general technical information related to hull and equipment damages, may bepassed on to IACS (International Association of Classification Societies) according to the associationworking rules;

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The documents and data are subject to a file management plan.ARTICLE 1010.1. - Any delay or shortcoming in the performance of its Services by the Society arising from an eventnot reasonably foreseeable by or beyond the control of the Society shall be deemed not to be a breach of contract.ARTICLE 1111.1. - In case of diverging opinions during surveys between the Client and the Society's surveyor, the So-ciety may designate another of its surveyors at the request of the Client.11.2. - Disagreements of a technical nature between the Client and the Society can be submitted by theSociety to the advice of its Marine Advisory Committee.ARTICLE 1212.1. - Disputes over the Services carried out by delegation of Governments are assessed within theframework of the applicable agreements with the States, international Conventions and national rules.12.2. - Disputes arising out of the payment of the Society's invoices by the Client are submitted to the Courtof Nanterre, France, or to another Court as deemed fit by the Society.12.3. - Other disputes over the present General Conditions or over the Services of the Society areexclusively submitted to arbitration, by three arbitrators, in London according to the ArbitrationAct 1996 or any statutory modification or re-enactment thereof. The contract between the Societyand the Client shall be governed by English law.ARTICLE 1313.1. - These General Conditions constitute the sole contractual obligations binding together theSociety and the Client, to the exclusion of all other representation, statements, terms, conditionswhether express or implied. They may be varied in writing by mutual agreement. They a re not var-ied by any purchase order or other document of the Client serving similar purpose.13.2. - The invalidity of one or more stipulations of the present General Conditions does not affect the va-lidity of the remaining provisions.13.3. - The definitions herein take precedence over any definitions serving the same purpose which mayappear in other documents issued by the Society.

BV Mod. Ad. ME 545 L - 7 January 2013

MARINE & OFFSHORE DIVISION

GENERAL CONDITIONS


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July 2014

RULE NOTE NR 600

NR 600Hull Structure and Arrangement

for the Classification of

Cargo Ships less than 65 m andNon Cargo Ships less than 90 m

Chapters 1 2 3 4 5 6

Chapter 1 General

Chapter 2 Structure Design Principles, General Arrangement andScantling Criteria

Chapter 3 Design Loads

Chapter 4 Hull Scantling

Chapter 5 Other Structure

Chapter 6 Construction and Testing

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2 Bureau Veritas July 2014

Unless otherwise specified, these rules apply to ships for which contracts aresigned after July 1 st, 2014. The Society may refer to the contents hereof beforeJuly 1st, 2014, as and when deemed necessary or appropriate.

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July 2014 Bureau Veritas 3

C HAPTER 1G ENERAL

Section 1 General1 General 23

1.1 Wording1.2 Classification

2 Application criteria 24

2.1 Type of ship covered by the present Rules2.2 Ship types not covered by the present Rules2.3 Particular cases

3 Navigation coefficients 243.1 Navigation notation3.2 Sea going launch and launch

4 Definitions 24

4.1 Length4.2 Breadth4.3 Depth4.4 Moulded draught4.5 Total block coefficient4.6 Chine and bottom4.7 Lightweight4.8 Deadweight4.9 Freeboard deck4.10 Bulkhead deck4.11 Superstructure4.12 Platform of multihull

5 Reference co-ordinate system 26

5.1 General

6 Stability 26

6.1 General

7 Documentation to be submitted 27

7.1 Documentation to be submitted

Section 2 Materials1 General 30

1.1 Application

2 Steels for hull structure 30

2.1 General

3 Aluminium alloys for hull structure 313.1 Characteristics and testing



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4 Composite materials and plywood for hull structure 31

4.1 Characteristics and testing4.2 Application

Section 3 Scantling Principles1 Main scantling principles 32

1.1 General1.2 Type of ships1.3 Corrosion addition1.4 Rounding off

2 Hull analysis approach 33

2.1 Hull girder and local strength2.2 Plating scantling approach



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C HAPTER 4H ULL S CANTLING

Section 1 General

1 Materials 81

1.1 General

2 Structure scantling approach 81

2.1 General2.2 Global strength analysis2.3 Local scantling analysis2.4 Specific cases

Section 2 Global Strength Analysis

1 General 82

1.1 Application1.2 Global strength calculation

2 Global strength check 82

2.1 General2.2 Maximum stress check2.3 Buckling check

3 Calculation of global strength for monohull ship 83

3.1 General3.2 Strength characteristics3.3 Overall stresses

4 Calculation of global strength of multihull 84

4.1 General4.2 Global strength in head sea condition4.3 Global strength of multihull in quartering sea and in digging in waves

4.4 Transverse bending moment acting on twin-hull connections of swath

Section 3 Local Plating Scantling

1 General 88

1.1 General1.2 Local loads

2 Plating scantling 88

2.1 General2.2 Scantling for steel and aluminium plating2.3 Scantling for composite panel



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Section 4 Local Secondary Stiffener Scantling

1 General 91

1.1 Local scantling

1.2 Local loads1.3 Section modulus calculation1.4 End stiffener conditions for section moduli calculation1.5 Span of stiffener

2 Secondary stiffener scantling 93

2.1 General2.2 Scantling for steel and aluminium secondary stiffener2.3 Scantling of secondary stiffeners in composite materials

Section 5 Local Primary Stiffener Scantling

1 General 96

1.1 Local scantling1.2 Structural beam models1.3 Finite element model1.4 Beam section modulus calculation1.5 End stiffener conditions for calculation

2 Primary stiffener scantling 97

2.1 Scantling for steel and aluminium primary stiffeners under lateral loads

2.2 Scantling for steel and aluminium primary stiffeners under wheeled loads2.3 Primary stiffeners in composite materials

3 Specific requirements 98

3.1 General3.2 Cut-outs and large openings3.3 Web stiffening arrangement for primary supporting members

Section 6 Stiffener Brackets Scantling and Stiffener End Connections

1 General arrangement of brackets 101

1.1 Materials1.2 General requirements

2 Bracket for connection of perpendicular stiffeners 101

2.1 General arrangement

3 Bracket ensuring continuity of secondary stiffeners 102

3.1 General

4 Bracketless end stiffeners connections 103

4.1 Bracketless end connections4.2 Other type of end connection



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Section 7 Pillar Scantling1 General 104

1.1 Materials1.2 Application

2 Pillar in steel material 105

2.1 Buckling of pillars subjected to compression axial load2.2 Buckling of pillars subjected to compression axial load and bending moments2.3 Vertical bulkhead stiffener acting as pillar

3 Pillar in aluminium material 106

3.1 General

4 Pillar in composite material 106

4.1 Global column buckling4.2 Local buckling

Appendix 1 Calculation of the Critical Buckling Stresses1 General 107

1.1 Application1.2 Materials

2 Plating 107

2.1 Calculation hypothesis

3 Secondary stiffeners 109


4 Primary stiffeners 110




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3 Machinery spaces 122

3.1 Application3.2 General3.3 Double bottom3.4 Single bottom3.5 Side3.6 Platforms3.7 Pillaring3.8 Machinery casing3.9 Seatings of main engines

4 Bow doors and inner doors 123

4.1 General4.2 Scantling and arrangement4.3 Securing and locking arrangement4.4 Operating and Maintenance Manual

5 Side doors and stern doors 1245.1 General5.2 Scantling and arrangement5.3 Securing and locking arrangement5.4 Operating and Maintenance Manual

6 Hatch covers 124

6.1 Small hatch covers6.2 Large hatch covers

7 Movable decks and inner ramps - External ramps 125

7.1 Application

7.2 Scantling7.3 Primary supporting members7.4 Supports, suspensions and locking devices7.5 Tests and trials7.6 External ramps

8 Rudders 126

8.1 General8.2 Rudder horn and solepiece scantlings

9 Water jet propulsion tunnel 127

9.1 General

10 Foils and trim tab supports 12810.1 General

11 Propeller shaft brackets 128

11.1 General

12 Bulwarks 128

12.1 General

13 Lifting appliances 128

13.1 General

14 Protection of metallic hull 12914.1 General



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Section 3 Helicopter Decks and Platforms1 Application 130

1.1 General1.2 Definition

2 General arrangement 130

2.1 Landing area and approach sector2.2 Sheathing of the landing area2.3 Safety net2.4 Drainage system2.5 Deck reinforcements

3 Design loads 130

3.1 Emergency landing load3.2 Garage load3.3 Specific loads for helicopter platforms

3.4 Local external pressures4 Scantlings 131

4.1 Plating4.2 Ordinary stiffeners4.3 Primary supporting members

Section 4 Additional Requirements in Relation to the Service Notation orService Feature Assigned to the Ship

1 General 1331.1 Service notations and service features1.2 Material

2 Ro-ro cargo ships 133

2.1 Application2.2 General2.3 Hull scantlings

3 Container ships 134

3.1 Application3.2 General

3.3 Structure design principles3.4 Design loads3.5 Hull scantlings3.6 Construction and testing

4 Livestock carriers 135

4.1 Application4.2 Ship arrangement4.3 Hull girder strength and hull scantlings

5 Bulk carriers 135

5.1 Application

5.2 Ship arrangement5.3 Structure design principles5.4 Design loads5.5 Hull scantlings



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5.6 Hatch covers5.7 Protection of hull metallic structure5.8 Construction and testing

6 Ore carriers 136

6.1 Application6.2 Ship arrangement6.3 Structure design principles6.4 Design loads6.5 Hull scantlings6.6 Hatch covers6.7 Construction and testing

7 Combination carriers 137

7.1 Application7.2 Ship arrangement7.3 Structure design principles

7.4 Design loads7.5 Hull scantlings7.6 Other structures7.7 Hatch covers7.8 Protection of hull metallic structures7.9 Cathodic protection of tanks7.10 Construction and testing

8 Oil tankers and FLS tankers 138

8.1 Application8.2 Ship arrangement8.3 Design loads8.4 Hull scantlings8.5 Other structures8.6 Protection of hull metallic structure8.7 Cathodic protection of tanks8.8 Construction and testing

9 Chemical tankers 139

9.1 Application9.2 Ship survival capability and location of cargo tanks9.3 Ship arrangement9.4 Cargo containment9.5 Other structures9.6 Protection of hull metallic structure9.7 Construction and testing

10 Tankers 139

10.1 Application10.2 Ship arrangement10.3 Design loads10.4 Hull scantlings10.5 Other structures

11 Passenger ships 140

11.1 Application11.2 Ship arrangement11.3 Design loads11.4 Hull scantlings11.5 Other structures



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12 Ro-ro passenger ships 141

12.1 Application12.2 Ship arrangement12.3 Structure design principles12.4 Design loads12.5 Hull scantlings12.6 Other structures

13 Tugs 141

13.1 Application13.2 Structure design principles13.3 Hull scantlings13.4 Other structures13.5 Towing arrangements13.6 Construction and testing13.7 Additional requirements for salvage tugs, for escort tugs and for anchor handling

vessels13.8 Integrated tug/barge combination

14 Supply vessels 142

14.1 Application14.2 Ship arrangement14.3 Access arrangement14.4 Structure design principles14.5 Design loads14.6 Hull scantlings14.7 Other structure14.8 Hull outfitting

15 Fire-fighting ships 143

15.1 Application15.2 Structure design principles15.3 Other structures

16 Oil recovery ships 143

16.1 Application16.2 Ship arrangement16.3 Hull scantlings16.4 Construction and testing

17 Cable-laying ships 144

17.1 Application17.2 Hull scantlings17.3 Other structures17.4 Equipment

18 Non-propelled units 144

18.1 Application18.2 Structure design principles18.3 Hull girder strength18.4 Hull scantlings18.5 Hull outfitting

19 Fishing vessels 145

19.1 Application19.2 Ship arrangement19.3 Hull scantling



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19.4 Specific design loads19.5 Hull scantlings19.6 Lifting appliances and fishing devices19.7 Hull outfitting19.8 Protection of hull metallic structure

20 Launch and seagoing launch 14820.1 Application20.2 Hull outfitting

Section 5 Anchoring Equipment and Shipboard fittings for Anchoring,Mooring and Towing Equipment

1 Design assumption for anchoring equipment 149

1.1 General

1.2 General case1.3 Specific cases

2 Anchoring equipment calculation 150

2.1 General2.2 Anchoring force calculation for monohull2.3 Anchoring force calculation for multihull

3 Equipment in chain and anchor 151

3.1 Anchors3.2 Chain cables3.3 Wire ropes and synthetic fibre ropes

3.4 Attachment pieces4 Shipboard fittings for anchoring equipment 154

4.1 Windlass and chain stopper4.2 Chain locker4.3 Anchoring sea trials

5 Shipboard fittings for towing and mooring 155

5.1 General



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C HAPTER 6C ONSTRUCTION AND T ESTING

Section 1 General1 General 159

1.12 Welding, welds and assembly of structure 159

2.1 Material3 Testing 159

3.1 General4 Construction survey 159

4.1 General

Section 2 Welding for Steel1 General 160

1.1 Materials1.2 Application1.3 Weld and welding booklet

2 Scantling of welds 1602.1 Butt welds2.2 Butt welds on permanent backing2.3 Fillet weld on a lap-joint2.4 Slot welds2.5 Plug welding2.6 Fillet weld

3 Typical joint preparation 1643.1 General3.2 Butt welding3.3 Fillet weld

4 Plate misalignment 1664.1 Misalignment in butt weld

4.2 Misalignment in cruciform connections

Section 3 Testing1 General 167

1.1 Application1.2 Definitions

2 Watertight compartments 1672.1 General2.2 Structural testing2.3 Hydropneumatic testing2.4 Leak testing2.5 Hose testing2.6 Other testing methods



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3 Miscellaneous 170

3.1 Watertight decks, trunks, etc.3.2 Doors in bulkheads above the bulkhead deck3.3 Steering nozzles3.4 Working test of windlass

Section 4 Construction Survey1 General 171

1.1 Scope

2 Structure drawing examination 171

2.1 General

3 Hull construction 171

3.1 Shipyard details and procedures3.2 Materials3.3 Forming3.4 Welding3.5 Inspection and check3.6 Modifications and repairs during construction

4 Survey for unit production 175

4.1 General

5 Alternative survey scheme for production in large series 175

5.1 General

5.2 Type approval5.3 Quality system documentation5.4 Manufacturing, testing and inspection plan (MTI plan)5.5 Society’s certificate



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NR 600

Chapter 1GENERAL

S ECTION 1 G ENERAL

S ECTION 2 MATERIALS

S ECTION 3 S CANTLING P RINCIPLE



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NR 600, Ch 1, Sec 1


2 Application criteria

2.1 Type of ship covered by the present Rules

2.1.1 General

The present Rules contain the requirements for the determi-nation of the hull scantlings (for the fore, central and aft partsof the ship) and structure arrangement applicable to the fol-lowing type of ships of normal form, speed and proportionsand built in steel, aluminium, or composite materials:

• cargo ships with L less than 65 m

• non-cargo ships with L less than 90 m.

2.1.2 Additional requirements applicable to specificships

a) Ship in aluminium

Specific additional requirements applicable to shipsbuilt in aluminium materials are defined in NR561 Alu-minium Ships.

b) Ship in composite materials

Specific additional requirements applicable to shipsbuilt in composite and/or plywood materials are definedin NR546 Composite Ships.

2.2 Ship types not covered by the presentRules

2.2.1 Liquefied gas carrier

Ships having the service notation liquefied gas carrier arenot covered by the present Rules and are to be in accord-ance with NR467 Steel Ships, Part B and Part D, Chapter 9.

2.2.2 Ships for dredging activity

Ships having one of the following service notations are notcovered by the present Rules and are to be in accordancewith NR467 Steel Ships, Part B and Part D, Chapter 13:

• dredger

• hopper dredger

• hopper unit

• split hopper dredger

• split hopper unit .

2.2.3 Cargo ships with alternate light and heavycargo loading conditions

As a rule, for ships having alternate light and heavy cargoloading conditions, the scantlings may be checked accord-ing to NR467 Steel Ships, Part B, Chapter 7 instead of thepresent Rules when deemed necessary by the Society.

2.3 Particular cases

2.3.1 Hull scantling

The Society reserves its right, whenever deemed necessary,to fully apply the requirements defined in NR467 SteelShips (dedicated for ships greater than 65 m in rule length)instead of the present Rules (see Sec 3, [2]).

2.3.2 Subdivision, compartment arrangement, andarrangement of hull openings

The requirements to be applied for the subdivision of thehull, the compartment arrangements and the arrangementof hull openings are defined in Ch 2, Sec 2, Tab 1.

3 Navigation coefficients

3.1 Navigation notation

3.1.1 The navigation coefficients n and n 1, which appear inthe formulae of the present Rules, are defined in Tab 2depending on the assigned navigation notation defined inNR467 Steel Ships, Pt A, Ch 1, Sec 2, [5.1].

Table 2 : Navigation coefficients n and n 1

3.2 Sea going launch and launch

3.2.1 For the service notations sea going launch and launch

as defined in NR467 Steel Ships, Pt A, Ch 1, Sec 2, [4.11.2],the navigation coefficients n and n 1, which appear in the for-mulae of the present Rules, are defined in Tab 3 .

Table 3 : Navigation coefficients n and n 1

4 Definitions

4.1 Length

4.1.1 Rule length

Rule length L is equal to the distance, in m, measured onthe summer load waterline, from the fore-side of the stem tothe after side of the rudder post, or to the centre of the rud-der stock where there is no rudder post. L is to be not lessthan 96% and need not exceed 97% of the extreme lengthon the summer load waterline.

Navigation notation n for localscantlingn1 for hull girder

scantling

unrestricted navigation 1,00 1,00

summer zone 0,90 0,95

tropical zone 0,80 0,90

coastal area 0,80 0,90

sheltered area 0,65 0,80

Service notation n for localscantlingn1 for hull girder

scantling

sea going launch 0,65 + 0,008 L w ≤ 1 0,80

launch 0,55 + 0,008 L w ≤ 1 0,70

Note 1:Lw : Lw = 0,5 (LWL + LHULL)

where:LWL : Length at waterline at full load, in mLHULL : Length of the hull from the extreme forward to

the extreme aft part of the hull, in m.



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NR 600, Ch 1, Sec 1


4.1.2 Ends of the rule length

The fore end (FP) of the rule length L is the perpendicular tothe summer load waterline at the forward side of the stem.

The aft end (AP) of the rule length L is the perpendicular tothe waterline at a distance L aft of the fore end.

4.1.3 Midship L CGThe midship LCG is the perpendicular to the waterline at adistance 0,5 L aft of the fore end.

4.1.4 Load line length

The load line length L LL is the distance, in m, on the water-line at 85% of the least moulded depth from the top of thekeel, measured from the forward side of the stem to the cen-tre of the rudder stock. L LL is to be not less than 96% of thetotal length on the same waterline.

In ship design with a rake of keel, the waterline on which

this length is measured is parallel to the designed waterlineat 85% of the least moulded depth D min found by drawing aline parallel to the keel line of the ship (including skeg) tan-gent to the moulded sheer line of the freeboard deck.Theleast moulded depth is the vertical distance measured fromthe top of the keel to the top of the freeboard deck beam atside at the point of tangency (see Fig 1).

Figure 1 : Length of ships with a rake of keel

4.1.5 Hull length

The hull length LHULL is equal to the distance, in m, meas-ured vertically from the fore end of the hull to the aft end of the hull.

4.1.6 Waterline length

The waterline length L WL is equal to the distance, in m,measured vertically from the intersection between the

waterline at full load displacement and the fore end and aftend of the hull.

4.2 Breadth

4.2.1 Moulded breadth

The moulded breadth B is the greatest moulded breadth, inm, measured amidships below the weather deck.

4.2.2 Waterline breadth

The waterline breadth B WL is the breadth, in m, measuredamidships at the moulded draught.

For catamaran, the waterline breadth B WL is to be measuredat one float at moulded draught.

For swath, the waterline breadth B ST is to be measured atone strut at moulded draught.

4.2.3 Breadth between multihull floatsThe breadth between floats B E is the distance, in m, measuredbetween the longitudinal planes of symmetry of the floats.

4.2.4 Breadth of submerged float of swathThe moulded breadth of submerged float of swath B SF is thegreatest moulded breadth, in m, measured amidships of thesubmerged float.

4.3 Depth

4.3.1 The depth D is the distance, in m, measured verti-cally on the midship transverse section, from the mouldedbase line to the top of the deck beam at side on the upper-most continuous deck.In the case of a ship with a solid bar keel, the moulded baseline is to be taken at the intersection between the upperface of the bottom plating with the solid bar keel at the mid-dle of length L.

4.4 Moulded draught

4.4.1 The moulded draught T is the distance, in m, meas-ured vertically on the midship transverse section, from themoulded base line to the summer load line.In the case of ships with a solid bar keel, the moulded baseline is to be taken as defined for the measurement of thedepth.

4.5 Total block coefficient

4.5.1 The total block coefficient is to be taken equal to:• For monohull:

• For catamaran:

• For swath:

where:Bm = (BSF DSF + BST (T − DSF)) / Twith:BSF : Breadth, in m, of the submerged floatDSF : Depth, in m, of the submerged floatBST : Breadth, in m, of the strutT : Moulded draught, in m.

4.6 Chine and bottom

4.6.1 ChineFor hulls that do not have a clearly identified chine, thechine is the hull point at which the tangent to the hull isinclined 50° to the horizontal.

4.6.2 BottomThe bottom is the part of the hull between the keel and thechines.

CB∆

1 025 LWLBWLT,---------------------------------------=

CB∆

1 025 LWL2BWLT,-------------------------------------------=

CB∆

1 025 LWL2BmT,----------------------------------------=



28/178


29/178

NR 600, Ch 1, Sec 1


7 Documentation to be submitted

7.1 Documentation to be submitted

7.1.1 Plans and documents to be submitted forapproval

a) GeneralThe plans and documents to be submitted to the Societyfor approval are listed in Tab 5.Structural plans are to show details of connections of the various parts and are to specified the materials used,including their manufacturing processes (see also Chap-ter 6).

b) Service notationThe plans and documents in relation to the service nota-tion to be submitted to the Society for approval arelisted in Tab 6.

c) Additional class notationThe plans and documents in relation to the additionalclass notation to be submitted to the Society forapproval are listed in Tab 7.

7.1.2 Plans and documents to be submitted forinformation

In addition to those in [7.1.1], the following plans and doc-uments are to be submitted to the Society for information:• general arrangement

• capacity plan, indicating the volume and position of thecentre of gravity of all compartments and tanks

• lightweight distribution.

In addition, when direct calculation analyses are carried outby the Designer according to the rule requirements, theyare to be submitted to the Society.

Table 5 : Plans and documents to be submitted for approval for all ships

Plan or document Containing also information on

Midship sectionTransverse sectionsShell expansionDecks and profilesDouble bottomPillar arrangementsFraming planDeep tank and ballast tank bulkheads, swashbulkheads

Class characteristicsMain dimensionsMinimum ballast draughtFrame spacingContractual service speedDensity of cargoesDesign loads on decks and double bottomSteel gradesLocation and height of air vent outlets of various compartmentsCorrosion protectionOpenings in decks and shell and relevant compensationsBoundaries of flat areas in bottom and sidesDetails of structural reinforcements and/or discontinuitiesBilge keel with details of connections to hull structures

Watertight subdivision bulkheadsWatertight tunnels

Openings and their closing appliances, if any

Fore part structure Location and height of air vent outlets of various compartments

Transverse thruster, if any, general arrangement,tunnel structure, connections of thruster withtunnel and hull structures

Aft part structure Location and height of air vent outlets of various compartments

Machinery space structuresFoundations of propulsion machinery and boilers

Type, power and r.p.m. of propulsion machineryMass and centre of gravity of machinery and boilers

Superstructures and deckhousesMachinery space casing

Extension and mechanical properties of the aluminium alloy used(where applicable)

Bow doors, stern doors and inner doors, if any,side doors and other openings in the side shell

Closing appliancesElectrical diagrams of power control and position indication circuits for bowdoors, stern doors, side doors, inner doors, television system and alarm systemsfor ingress of water

Hatch covers, if any Design loads on hatch coversSealing and securing arrangements, type and position of locking boltsDistance of hatch covers from the summer load waterline and from the fore end

Movable decks and ramps, if any

(1) Where other steering or propulsion systems are adopted (e.g. steering nozzles or azimuth propulsion systems), the plans show-ing the relevant arrangement and structural scantlings are to be submitted.



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NR 600, Ch 1, Sec 1


Table 6 : Plans and documents to be submitted depending on service notations

Windows and side scuttles, arrangements anddetails

Bulwarks and freeing ports Arrangement and dimensions of bulwarks and freeing ports on the freeboarddeck and superstructure deck

Helicopter decks, if any General arrangementMain structureCharacteristics of helicopters: maximum mass, distance between landing gearsor landing skids, print area of wheels or skids, distribution of landing gear loads

Rudder and rudder horn (1) Maximum ahead service speed

Stern frame or sternpost, stern tube (1)Propeller shaft boss and brackets

Derricks and cargo gearCargo lift structures

Design loads (forces and moments)Connections to the hull structures

Sea chests, stabiliser recesses, etc.

Hawse pipes

Plan of outer doors and hatchways

Plan of manholes

Plan of access to and escape from spaces

Plan of tank testing Testing procedures for the various compartmentsHeight of pipes for testing

Plan of watertight doors and scheme of relevantmanoeuvring devices

Manoeuvring devicesElectrical diagrams of power control and position indication circuits

Equipment number calculation Geometrical elements for calculationList of equipmentConstruction and breaking load of steel wires

Material, construction, breaking load and relevant elongation of synthetic ropes

Service notations (1) Plans or documentsRo-ro passenger shipRo-ro cargo ship

Plans of the bow or stern ramps, elevators for cargo handling and movable decks, if any, including:• structural arrangements of ramps, elevators and movable decks with their masses• arrangements of securing and locking devices• connection of ramps, lifting and/or hoisting appliances to the hull structures, with indication of design

loads (amplitude and direction)• wire ropes and hoisting devices in working and stowed position• hydraulic jacks• loose gear (blocks, shackles, etc.) indicating the safe working loads and the testing loads• test conditionsOperating and maintenance manual of bow and stern doors and rampsPlan of arrangement of motor vehicles, railway cars and/or other types of vehicles which are intended to becarried and indicating securing and load bearing arrangementsCharacteristics of motor vehicles, railways cars and/or other types of vehicles which are intended to be car-ried: (as applicable) axle load, axle spacing, number of wheels per axle, wheel spacing, size of tyre printPlan of dangerous areas, in the case of ships intended for the carriage of motor vehicles with petrol in their tanks

Container ship Container arrangement in holds, on decks and on hatch covers, indicating size and gross mass of containersContainer lashing arrangement indicating securing and load bearings arrangementsDrawings of load bearing structures and cell guides, indicating the design loads and including the connec-

tions to the hull structures and the associated structural reinforcements(1) as defined in NR467 Steel Ships, Part A.

Plan or document Containing also information on

(1) Where other steering or propulsion systems are adopted (e.g. steering nozzles or azimuth propulsion systems), the plans show-ing the relevant arrangement and structural scantlings are to be submitted.



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NR 600, Ch 1, Sec 1


Table 7 : Plans and documents to be submitted depending on additional class notations

Livestock carrier Livestock arrangementDistribution of fodder and consumable liquid on the various decks and platforms

Oil tanker ESPFLS tanker

Arrangement of pressure/vacuum valves in cargo tanksCargo temperatures

Tanker Cargo temperaturesChemical tanker List of cargoes intended to be carried, with their density

Types of cargo to be carried in each tankCargo temperaturesArrangement of pressure/vacuum valves in cargo tanksFor ships with independent tanks, connection of the cargo tanks to the hull structure

TugSalvage tugTug escort

Connection of the towing system (winch and hook) with the hull structures with indication of design loads

Tug, Salvage tug, Tugescort with additionalservice feature bargecombined

Structural arrangement of the fore part of the tug, showing details of reinforcements in way of the connect-ing pointStructural arrangement of the aft part of the barge, showing details of reinforcements in way of the connect-ing pointDetails of the connection systemBarge with additional

service feature tugcombinedSupply vessel General plan showing the location of storage and cargo tanks with adjacent cofferdams and indicating the

nature and density of cargoes intended to be carriedPlan of gas-dangerous spacesConnection of the cargo tanks with the hull structureStowage of deck cargoes and lashing arrangement with location of lashing points and indication of design loadsStructural reinforcements in way of load transmitting elements, such as winches, rollers, lifting appliances

Oil recovery ship General plan showing the location of tanks intended for the retention of oily residues and systems for theirtreatment

Plan of the system for treatment of oily residues and specification of all relevant apparatusesSupporting structures of the system for treatment of oily residuesOperating manual

Cable laying ship Structural reinforcements in way of load transmitting elements, such as foundations and fastenings of theequipment to the ship structures

Fishing vessel Minimum design temperature of refrigerated spacesStructural reinforcements in way of load transmitting elements, such as masts, gantries, trawl gallows andwinches, including the maximum brake load of the winches

Additional class notation (1) Plans or documentsICE CLASS IA SUPERICE CLASS IAICE CLASS IBICE CLASS ICICE CLASS ID

The plans relevant to shell expansion and fore and aft part structures are to define the maximumdraught LWL, the minimum draught BWL (both draughts at midship, fore and aft ends), and the bor-derlines of fore, midship and aft regions (see NR467 Steel Ships, Part E, Chapter 8)

LASHING Lashing arrangement plans, indicating:• container arrangement in holds, on decks and on hatch covers, with specification of the gross

mass of each container and of each container stack• arrangement of mobile lashing equipment with the specific location of the various pieces of

equipmentComplete list of the mobile lashing equipment, with detailed drawing and indication of materials,

safety working loads, breaking loads or test toadsRemovable load-bearing structures for containers, such as guides, cells, buttresses, etc., connected tothe hull structure or to hatch covers

(1) as defined in the NR467 Steel Ships, Part A.

Service notations (1) Plans or documents

(1) as defined in NR467 Steel Ships, Part A.



32/178

NR 600, Ch 1, Sec 2


SECTION 2 M ATERIALS

1 General

1.1 Application

1.1.1 This Section defines the main characteristics to takeinto account for steels, aluminium alloys or compositematerials within the scope of the determination of the hullscantling as defined in the present Rules.

1.1.2 Materials and products such as parts made of iron

castings, where allowed, products made of copper and cop-per alloys, rivets, anchors, chain cables, cranes, masts, der-rick posts, derricks, accessories and wire ropes are tocomply with the applicable requirements of NR216 Materi-als and Welding.

1.1.3 Materials with different characteristics may be con-sidered, provided their specification (manufacture, chemi-cal composition, mechanical properties, welding, etc.) issubmitted to the Society for approval.

2 Steels for hull structure

2.1 General

2.1.1 Characteristics of materials

The characteristics of steels to be used in the construction of ships are to comply with the applicable requirements of NR216 Materials and Welding.

2.1.2 Testing and manufacturing process

Materials are to be tested in compliance with the applicablerequirements of NR216 Materials and Welding.

The requirements of this Section presume that welding andother cold or hot manufacturing processes (parent materialtypes and welding, preheating, heat treatment after weld-ing, etc.) are carried out in compliance with current soundworking practice and the applicable requirements of NR216Materials and Welding.

2.1.3 Mechanical characteristics of hull steels

The mechanical characteristics of steels are to comply withthe requirements of NR467 Steel Ships, Pt B, Ch 4, Sec 1,and in particular the:

• grade of steel to be used for the various strength mem-bers of the structure

• grade of steel for structure exposed to low temperatures(air and/or refrigerated spaces)

• steels for forging and casting.

Table 1 : Mechanical properties of hull steels

Tab 1 gives the mechanical properties of steels currentlyused in the construction of ships as a reminder.

Higher strength steels other than those indicated in Tab 1are considered by the Society on a case-by-case basis.

When steels with a minimum specified yield stress R eH otherthan 235 N/mm 2 are used on a ship, hull scantlings are to

be determined by taking into account the material factor kdefined in [2.1.4].

2.1.4 Material factor k for scantling

As a rule, the scantling of structure element is based on asteel material of minimum yield stress R eH equal to235 N/mm 2.

A material factor k is used in the scantling formulae to takeinto account steel materials with other values of minimumyield stress.

Unless otherwise specified, the material factor k has the val-ues defined in Tab 2, as a function of the minimum speci-fied yield stress ReH.

For intermediate values of R eH , k may be obtained by linearinterpolation.

Steels with a yield stress lower than 235 N/mm 2 or higherthan 390 N/mm 2 are considered by the Society on a case-by-case basis.

Table 2 : Material factor k

Steel gradest ≤ 100 mm

Minimum yieldstress ReH ,in N/mm 2

Ultimate minimumtensile strength R m ,

in N/mm 2

A-B-D-E 235 400 - 520

AH32-DH32-EH32FH32

315 440 - 590

AH36-DH36-EH36FH36

355 490 - 620

AH40-DH40-EH40FH40

390 510 - 650

Note 1: Refer to NR216 Materials and Welding, Ch 2, Sec 1,[2].

ReH , in N/mm 2 k

235 1,00

315 0,78

355 0,72

390 0,68



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NR 600, Ch 1, Sec 2


2.1.5 Minimum yield stress for scantling criteria ofhull structure

The minimum yield stress of steel R y , in N/mm 2, used forthe scantling criteria of the hull structure is to be taken,unless otherwise specified, equal to:

where:

k : Material factor defined in [2.1.4].

3 Aluminium alloys for hull structure

3.1 Characteristics and testing

3.1.1 The characteristics of aluminium alloys to be used inthe construction and their testing process are to complywith the applicable requirements of the following Rules:

• NR216 Materials and Welding

• NR561 Aluminium Ships.

Materials with different characteristics may be accepted,provided their specification (manufacture, chemical com-position, mechanical properties, welding, etc.) is submittedto the Society for approval.

3.1.2 Material factor k for scantling

As a rule, the scantling of structure element is based on analuminium alloy in welded condition of minimum yieldstress R’

lim equal to 100 N/mm 2.

A material factor k, used on the scantling formula to takeinto account aluminium alloy in welded condition withother values of minimum yield stress, is to be taken equalto:

where:

R’lim : Minimum yield stress of the aluminium alloysconsidered, to be taken equal to the minimumvalue, in welded condition, between R ’p0,2(proof stress) and 0,7 R ’m (tensile strength),where R ’p0,2 and R ’m are defined in NR561 Alu-

minium Ships.3.1.3 Minimum yield stress for scantling criteria of

hull structureThe minimum yield stress of aluminium R y , in N/mm 2, usedfor the scantling criteria of the hull structure is to be taken,unless otherwise specified, equal to:

where:k : Material factor defined in [3.1.2].

4 Composite materials and plywood

for hull structure4.1 Characteristics and testing

4.1.1 The characteristics of composite materials and ply-wood and their testing and manufacturing process are tocomply with the applicable requirements of NR546 Com-posite Ships, in particular for the:• raw materials• laminating process• mechanical tests and raw material homologation.

4.2 Application

4.2.1 Attention is drawn to the use of composite and/or ply-wood materials from a structural fire protection point of view.The Flag Administration may request that international con-vention be applied instead of the present requirements,entailing in some cases a use limitation of composite and/orplywood materials.

Ry 235 k ⁄ =

k 100 R ′ lim ⁄ =

Ry 100 k ⁄ =



34/178

NR 600, Ch 1, Sec 3


SECTION 3 S CANTLING P RINCIPLES

Symbols

L : Rule length, in m, as defined in Sec 1, [4.1.1].

1 Main scantling principles

1.1 General

1.1.1 The present Section defines the main scantling princi-

ples considered in the present Rules.

1.2 Type of ships

1.2.1 General

Two groups of ship are defined, taking into account specificshape of hull (see definition in Sec 1, [1.1.2]):

• Cargo ship

• Non-cargo ship.

Ship motions and accelerations of ship under examination

are calculated in relation to its group.The longitudinal distribution of ship motions and accelera-tions along the ship length are defined on four differentareas, as follows (see Fig 1):

• 1st area: from aft part to 0,25 L

• 2nd area: from 0,25 L to 0,70 L

• 3rd area: from 0,70 L to 0,85 L

• 4th area: from 0,85 L to the fore part.

Ship motions and accelerations of each area are calculatedin the middle of the area and are considered as constantalong the area.As a rule, ship motions and accelerations are calculated inhead sea condition.

Figure 1 : Definition of longitudinal areas

1.2.2 Specific case of high speed shipThe structure of the high speed ship with planing hull is tobe examined in the two following conditions of navigation:• when the ship sails in a displacement mode:

as cargo or non-cargo ship, as applicable, and• when the sea conditions allow to sail at the maximum

contractual speed in planing hull mode:as a high speed ship.

The global and local loads, and the permissible stressesconsidered to check the structure are specific to each of these two conditions of navigation.

1.3 Corrosion addition

1.3.1 Steel shipsThe scantlings obtained by applying the criteria specified inthe present Rules for steel structure are gross scantling, i.e.they include additions for corrosion.As a rule, the included corrosion additions are equal to:

• 15% of the local scantling of an individual plate ele-ment required to sustains the loads• 20% of the local scantling of an individual stiffener ele-

ment required to sustains the loads• 10% of the local scantling of a set of element (plate or

longitudinal) contributing to the longitudinal globalstrength.

1.3.2 Aluminium shipsThe scantlings obtained by applying the criteria specified inthe present Rules for aluminium structure are gross scant-ling, i.e they include additions for local corrosion.

As a rule, the included corrosion additions is equal to 5% of the scantling required to sustains the loads.

1.3.3 Composite shipsThe scantlings obtained by applying the criteria specified inthe present Rules for composite structure include a rule par-tial safety coefficient, C V, taking into account the ageingeffect on the laminate mechanical characteristics.

1.4 Rounding off

1.4.1 The rounding off of plate thicknesses on metallichulls is to be obtained from the following procedure:

a) the thickness is calculated in accordance with the rulerequirements

b) the rounded thickness is taken equal to the valuerounded off to the nearest half-millimetre.L

1 st area 2 nd area 3 rd area 4 th area

0,25 L0,70 L

0,85 L



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NR 600, Ch 1, Sec 3


Stiffener section moduli as calculated in accordance withthe rule requirements are to be rounded off to the neareststandard value. However, no reduction may exceed 3%.

2 Hull analysis approach

2.1 Hull girder and local strength

2.1.1 General

As a rule, the global hull girder strength and the localstrength are examined independently in the present Rules,as follows:

• the longitudinal scantling of the hull girder is examinedon the basis of a maximum permissible stress at deckand bottom and a buckling check of elements contribut-ing to the hull girder strength

• the local scantling is examined on the basis of local per-missible stresses defined in relation to the type of localloads applied and the type of structure element.

2.1.2 Particular case

As a rule, the requirements of NR467 Steel Ships,Chapter 7, dedicated for ships greater than 65 m, are to befully applied instead of the present Rules when:

• the global stress, in N/mm 2, calculated according to Ch 4,Sec 2 (excluding the case of the minimum bendingmoment for high speed ship calculated according to Ch 3,Sec 2, [6.1] ) is greater than 0,35 R y, where Ry is defined inSec 2, [2.1.5] for steel structure and in Sec 2, [3.1.3] foraluminium structure.

• when deemed necessary by the Society.

For ship built in composite materials, a combination withthe global hull girder stresses for the local scantling analysismay be carried out when deemed necessary by the Society.

2.2 Plating scantling approach

2.2.1 GeneralThe plating scantlings obtained by applying the criteriaspecified in the present Rules are based on a simplify elasticbehaviour of plating under lateral loads approach.

2.2.2 Other plating scantling approachWhen deemed necessary, it may be considered a platingscantling approach based on a plastic behaviour of platingunder lateral loads.In this case, the requirements of NR467 Steel Ships,Chapter 7, dedicated for ships greater than 65 m, are to befully applied, instead of the present Rules, to check the hullstructure.



36/178

NR 600, Ch 1, Sec 3




37/178


NR 600

Chapter 2STRUCTURE DESIGN PRINCIPLES,

GENERAL ARRANGEMENT ANDSCANTLING CRITERIA

S ECTION 1 S TRUCTURE DESIGN P RINCIPLES

S ECTION 2 S UBDIVISION , C OMPARTMENT A RRANGEMENT , AND ARRANGEMENT OF HULL O PENINGS

S ECTION 3 S CANTLING C RITERIA



38/178




39/178

NR 600, Ch 2, Sec 1


SECTION 1 S TRUCTURE DESIGN P RINCIPLES

1 General

1.1 Application

1.1.1 Steel structure

The requirements of the present Section apply to longitudi-nally or transversely frame structure arrangement of hullbuilt in steel materials for:

• structural continuity of hull

• single and double bottoms

• sides and decks

• transverse and longitudinal structures

• superstructures and deckhouses

• special features.

Any other arrangement may be considered on a case-by-case basis.

Additional specific structure design principles in relation tothe service notation of the ship are defined in Ch 5, Sec 4.

1.1.2 Aluminium structure

Equivalent arrangements for hull built in aluminium alloysare defined in NR561 Aluminium Ships.

1.1.3 Composite and plywood structure

Equivalent arrangements for hull built in composite materi-als and/or plywood are defined in NR546 Composite Ships.

2 Structural continuity of hull girder

2.1 General principles for longitudinal hullgirder

2.1.1 Attention is to be paid to the structural continuity:• in way of changes in the framing system

• at the connections of primary and secondary stiffeners.

2.1.2 Longitudinal members contributing to the hull girderlongitudinal strength are to extend continuously over a suf-ficient distance towards the ends of the ship.

Secondary stiffeners contributing to the hull girder longitu-dinal strength are generally to be continuous when crossingprimary supporting members. Otherwise, the detail of con-nections is considered by the Society on a case-by-casebasis.

2.1.3 Where stress concentrations may occur in way of structural discontinuity, adequate compensation and rein-forcements are to be provided.

2.1.4 Openings are to be avoided, as far as practicable, inway of highly stressed areas.

Where necessary, the shape of openings is to be speciallydesigned to reduce the stress concentration factors.

Openings are to be generally well rounded with smoothedges.

2.1.5 Primary supporting members are to be arranged insuch a way that they ensure adequate continuity of strength.Abrupt changes in height or in cross-section are to be

avoided.

2.2 General principles for platform of multihull

2.2.1 Attention is to be paid to the structural continuity of the primary transverse cross structure of the platform ensur-ing the global transversal resistance of the multihull.

The primary transverse cross structure of catamaran are gen-erally to be continuous when crossing float structures.

The connection between the transverse cross structure of swath and struts are to be examined by direct calculation.

The general continuity principles defined in [2.1] also applyfor the primary transverse cross structure of the platform.

2.3 Insert plates and doublers

2.3.1 A local increase in plating thickness is generally to beachieved through insert plates. Local doublers, which arenormally only allowed for temporary repair, may howeverbe accepted by the Society on a case-by-case basis.

In any case, doublers and insert plates are to be made of materials of a quality at least equal to that of the plates onwhich they are welded.

2.3.2 Doublers having width, in mm, greater than:

• 20 times their thickness, for thicknesses equal to or lessthan 15 mm

• 25 times their thickness, for thicknesses greater than15 mm,

are to be fitted with slot welds, to be effected according toChapter 6.

2.3.3 When doublers fitted on the outer shell and strengthdeck within 0,6 L amidships are accepted by the Society,their width and thickness are to be such that slot welds arenot necessary according to the requirements in [2.3.2]. Out-side this area, the possibility of fitting doublers requiringslot welds will be considered by the Society on a case-by-case basis.



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NR 600, Ch 2, Sec 1


2.4 Connections between steel and aluminium

2.4.1 Any direct contact between steel and aluminiumalloy is to be avoided.

Any heterogeneous jointing system is considered by the

Society on a case-by-case basis.The use of transition joints made of aluminium/steel-cladplates or profiles is to be in accordance with NR216 Materi-als and Welding.

3 Bottom structure arrangement

3.1 General arrangement

3.1.1 The bottom structure is to be checked by theDesigner to make sure that it withstands the loads resultingfrom the dry-docking of the ship or the lifting by crane,when applicable. This check under such loading cases isnot within the scope of classification.

3.1.2 Provision is to be made for the free passage of waterfrom all the areas of the bottom to the suctions, by means of scallops in floors and bottom girders.

3.1.3 Additional girder and floors may be fitted in theengine room to ensure adequate rigidity of the structure,according to the recommendations of the engine supplier.

3.1.4 If fitted, solid ballast is to be securely positioned. If necessary, intermediate girders and floors may be required.

The builder is to check that solid ballast material is compat-ible with the hull material.

3.1.5 Where face plates of floors and girders are at samelevel, the face plate of the stiffer member is generally to becontinuous. Butt welds of faces plates are to providestrength continuity.

3.1.6 As a rule, bottom girders are to be fitted in way of each line of pillars. If it is not the case, local longitudinalmembers are to be provided.

3.2 Longitudinal framing arrangement ofsingle bottom

3.2.1 As a general rule, hull with a longitudinally framedsingle bottom is to be fitted with a continuous or inter-coastal centre girder welded to the floors.

3.2.2 Where side girders are fitted locally in lieu of centregirder, they are to be extended over a sufficient distancebeyond the ends of the centre girder and an additional stiff-ening of the bottom in the centreline area may be required.

3.2.3 Centre and side bottom girders are to be extended asfar as possible towards the ends of the hull.

3.2.4 Cut-outs fitted in web of floors for crossing of bottomlongitudinal are to be taken into account for the shear anal-ysis of floors.

3.3 Transverse framing arrangement ofsingle bottom

3.3.1 Requirements of [3.1] apply also to transverse fram-ing in single bottom.

3.3.2 In general, the height, in m, of floors at the centrelineshould not be less than B/16. In the case of ship with con-siderable rise of floors, this height may be required to beincreased so as to ensure a satisfactory connection to theframes.

3.3.3 The ends of floors at side are to be aligned with sidetransverse members.It may be accepted, on a case-by-case basis, that floor endsat side be welded on a primary longitudinal member of theside shell or the bottom.

3.3.4 Openings and cut-outs in the web of bottom girders

for the crossing of floors are to be taken into account for thefloor shear analysis.

3.4 Double bottom arrangement

3.4.1 Double bottom heightAs a general rules, the double bottom height is to be:• sufficient to ensure access to any part of the bottom, and• not less than 0,76 m in way of the centre girder.

3.4.2 Where the height of the double bottom varies, thevariation is generally to be made gradually and over an ade-quate length.The knuckles of inner bottom plating are to be located inway of floors.

Where such arrangements are not possible, suitable longitu-dinal structures such as partial girders, longitudinal bracketsetc., fitted across the knuckle, are to be fitted.

3.4.3 Adequate continuity is to be provided between dou-ble bottom area and single bottom area.

3.4.4 Floors are to be fitted:• watertight in way of transverse watertight bulkheads• reinforced in way of double bottom steps.

3.4.5 Where the double bottom height exceeds 0,9 m, webof floors and girders are to be strengthened by vertical stiff-eners spaced not more than 1 m apart.These stiffeners may consist of:• either bottom girders welded to the floors, or• flat bars with, as a rule, a width equal to one tenth of the

floor depth and a thickness equal to the floors thickness.

3.4.6 Watertight floors are to be fitted with stiffeners havinga section modulus not less than that required for tank bulk-head vertical stiffeners.

3.4.7 In case of open floors consisting of a frame con-nected to the bottom plating and a reverse frame connectedto the inner bottom plating, the construction principle is tobe as shown on Fig 1.



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NR 600, Ch 2, Sec 1


Figure 1 : Open floor

3.4.8 Double bottom compartment

Double bottom compartments are to be in accordance withSec 2, [4].

3.4.9 Duct keel

Where a duct keel is arranged, the continuity of the struc-ture of the floors is to be ensured.

3.5 Arrangement, scantlings and connectionsof bilge keels

3.5.1 Arrangement

Bilge keels may not be welded directly on the shell plating.An intermediate flat, or doubler, is required on the shellplating.

The thickness of the intermediate flat is to be equal to that of

the bilge strake.

The ends of the bilge keels are to be sniped at an angle of 15° or rounded with large radius. They are to be located inway of a transverse bilge stiffener. The ends of the interme-diate flat are to be sniped at an angle of 15°.

The arrangement shown in Fig 2 is recommended.

The arrangement shown in Fig 3 may also be accepted.

Figure 2 : Bilge keel arrangement

Figure 3 : Bilge keel arrangement

3.5.2 MaterialsThe bilge keel and the intermediate flat are to be made of steel with the same yield stress and grade as that of the bilgestrake.

3.5.3 Welding

Welding of bilge keel with intermediate plate connectionsis to be in accordance with Ch 6, Sec 2.

4 Side structure arrangement

4.1 General

4.1.1 In a transverse framing system, structure of sides ismade of secondary transverse frames, possibly supported byhorizontal stringers.

4.1.2 In a longitudinal framing system, structure of sidesare made of secondary longitudinal stiffeners supported byvertical primary supporting members.

4.1.3 Where the connection between side shell and deckplate is rounded, the radius, in mm, is to be not less than15 tS, where t S is the thickness, in mm, of the sheerstrake.

4.2 Stiffener arrangement

4.2.1 In general, the section modulus of ‘tweendeck framesis to be not less than that required for frames located imme-diately above.

4.2.2 Transverse web frames and secondary side frames areto be attached to floors and deck beams by brackets or anyother equivalent structure (see Ch 4, Sec 6).

4.2.3 For transverse framing system, the attention of theDesigner is drawn on the risk of buckling of side shell platepanels in way of ends of frames. Extra-thickness or addi-tional intercostal stiffeners may be requested in these areason the side shell.

shell plating



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NR 600, Ch 2, Sec 1


4.3 Openings in the side shell plating

4.3.1 Openings in side shells are to be well rounded at thecorners and located, as far as practicable, well clear of superstructure ends.

4.3.2 Large size openings are to be adequately compen-sated by means of insert plates of increased thickness. Suchcompensation is to be partial or total, depending on thestresses occurring in the area of the openings.

4.3.3 Secondary stiffeners cut in way of openings are to beattached to local structural members supported by the con-tinuous adjacent secondary stiffeners, or any other equiva-lent arrangement.

4.3.4 The sea chest thickness is generally to be equal tothat of the local shell plating

4.3.5 Openings for stabilizer fins are considered by theSociety on a case-by-case basis.

5 Deck structure arrangement

5.1 General

5.1.1 Adequate continuity of decks (plates and stiffeners) isto be ensured in way of:

• stepped strength decks

• changes in the framing system• large openings.

5.1.2 Deck supporting structures under cranes and wind-lass are to be adequately stiffened.

5.1.3 Pillars or other supporting structures are generally tobe fitted under heavy concentrated loads on decks.

5.1.4 Stiffeners are also to be fitted in way of the ends andcorners of deck houses and partial superstructures.

5.1.5 Beams fitted at side of a deck hatch are to be effec-tively supported by at least two deck girders located at eachside of the deck opening.

5.2 Opening arrangement

5.2.1 The deck openings are to be as much spaced apart aspossible.

As practicable, they are to be located as far as possible fromthe highly stressed deck areas or from the stepped deckareas.

5.2.2 Extra thickness or additional reinforcements may berequested where deck openings are located:

• close to the primary transverse cross structure of plat-form of multihull

• in areas of deck structural singularity (cockpit, steppeddeck...)

• in way of the fixing of out-fittings.

5.2.3 As a rule, all the deck openings are to be fitted with

radius corners. Generally, the corner radius is not to be lessthan 5% of the transverse width of the opening.

5.2.4 Corner radiusing, in the case of two or more openingsathwart ship in one single transverse section, is consideredby the Society on a case-by-case basis.

5.3 Hatch supporting structure

5.3.1 Hatch side girders and hatch end beams of reinforcedscantling are to be fitted in way of cargo hold openings.

In general, hatched end beams and deck transverses are to

be in line with bottom and side transverse structures, so asto form a reinforced ring.

Adequate continuity of strength of longitudinal hatch coam-ings is to be ensured.

The details of connection of deck transverses to longitudinalgirders and web frames are to be submitted to the Societyfor approval.

5.4 Pillars arrangement under deck

5.4.1 Pillars are to be connected to the inner bottom at theintersection of girders and floors and at deck at the intersec-tion of deck beams and deck girders.

Where it is not the case, an appropriate local partial struc-ture is to be fitted to support the pillars.

5.4.2 Pillars are to be attached at their heads and heels bycontinuous welding.

Heads and heels of pillars are to be attached to the sur-rounding structure by means of brackets, insert plates ordoubling plates so that the loads are well distributed.

In general, the thickness of insert plate or doubling plates isto be not less than 1,5 times the thickness of the pillar.

5.4.3 If tensile stress is expected in the pillar, an insert plateis to be put in place of doubling plate and head and heelbrackets may be required.

5.4.4 In tanks and in spaces intended for products whichmay procure explosive gases, solid or open section pillarsare to be fitted.

5.4.5 Manholes may not be cut in the girders and floorsbelow the heels of pillars.

5.4.6 Tight or non-tight bulkheads may be considered as pil-lars, provided that their scantling comply with Ch 4, Sec 7.

5.4.7 The scantlings of pillars are to comply with therequirements of Ch 4, Sec 7.



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NR 600, Ch 2, Sec 1


6 Bulkhead structure arrangement

6.1 General

6.1.1 Plane bulkheads may be horizontally or vertically

stiffened.Stiffening of horizontally framed bulkheads consists of hori-zontal secondary stiffeners supported by vertical primarysupporting members.

Stiffening of vertically framed bulkheads consists of verticalsecondary stiffeners which may be supported by horizontalstringers.

The structural continuity of the vertical and horizontal pri-mary supporting members with the surrounding supportinghull structures is to be carefully ensured.

6.1.2 As a general rule, transverse bulkheads are to be stiff-

ened, in way of bottom and deck girders, by vertical stiffen-ers in line with these girders or by an equivalent system.Where a deck girder is not continuous, the bulkhead verti-cal stiffener supporting the end of the deck girder is to bestrong enough to sustain the bending moment transmittedby the deck girder.

6.2 Watertight bulkheads

6.2.1 Crossing through watertight transverse bulkheads of bottom, side shell or deck longitudinal stiffeners are toclosed by watertight collar plates.

6.2.2 Ends of stiffeners of watertight bulkheads are to bealigned with the hull structure members, and are to be fittedwith end brackets.Where this arrangement is made impossible due to hulllines, any other solution may be accepted provided embed-ding of the bulkhead secondary stiffeners is satisfactorilyachieved.

6.2.3 The secondary stiffeners of watertight bulkheads inthe ‘tweendecks may be snipped at ends, provided theirscantling is increased accordingly.

6.2.4 Watertight doors

The thickness of watertight doors is to be not less than theadjacent bulkhead plating, taking into account their actualspacing.

Where bulkhead stiffeners are cut in way of watertight door,reinforced stiffeners are to be fitted and suitably overlapped;cross-bars are to be provided to support the interrupted stiff-eners.

6.3 Non-tight bulkheads

6.3.1 As a rule, non-tight bulkheads not acting as pillars areto be provided with vertical stiffeners with a maximumspacing equal to:• 0,9 m, for transverse bulkheads• two-frame spacings, with a maximum of 1,5 m, for lon-

gitudinal bulkheads.

6.3.2 Swash bulkheadsAs a rule, the total area of openings in swash bulkheads fit-ted in tanks is to be between 10% and 30% of the total areaof the swash bulkhead.

6.4 Corrugated bulkheads6.4.1 GeneralThe main dimensions a, b, c and d of corrugated bulkheadsare defined in Fig 4.Unless otherwise specified, the following requirement is tobe complied with:

Moreover, in some cases, the Society may prescribe anupper limit for the ratio b/t.In general, the bending internal radius is to be not less thanthe following values, in mm:

• for normal strength steel:Ri = 2,5 t

• for high tensile steel:Ri = 3,0 t

When welds in a direction parallel to the bend axis are pro

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