Dnv Alu Structures Hsc

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RULES

DET NORSKE VERITAS (DNV)

= STRUCTURES =Aluminium High Speed, Light Craft

PART 3 - CHAPTER 1

High Speed, Light Craft

Design Principles, Design Loads

and

PART 3 - CHAPTER 3

Hull Structural Design, Aluminium Alloy

(DNV) JANUARY 2011


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RULES FOR CLASSIFICATION OF

DETNORSKEVERITASAS

The content of this service document is the subject of intellectual property rights reserved by Det Norske Veritas AS (DNV). The useraccepts that it is prohibited by anyone else but DNV and/or its licensees to offer and/or perform classification, certification and/orverification services, including the issuance of certificates and/or declarations of conformity, wholly or partly, on the basis of and/orpursuant to this document whether free of charge or chargeable, without DNV's prior written consent. DNV is not responsible for theconsequences arising from any use of this document by others.

High Speed, Light Craft andNaval Surface Craft

PART 3 CHAPTER 1

STRUCTURES, EQUIPMENT

Design Principles, Design LoadsJANUARY 2011

This chapter has been amended since the main revision (January 2011), most recently in July 2011.See Changes on page 3.


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FOREWORD

DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life,property and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification andconsultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, andcarries out research in relation to these functions.

The Rules lay down technical and procedural requirements related to obtaining and retaining a Class Certificate. It is usedas a contractual document and includes both requirements and acceptance criteria.

The electronic pdf version of this document found through http://www.dnv.com is the officially binding version Det Norske Veritas AS January 2011

Any comments may be sent by e-mail to [email protected] subscription orders or information about subscription terms, please use [email protected]

Computer Typesetting (Adobe Frame Maker) by Det Norske Veritas

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation tosuch person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided thatthe maximum compensation shall never exceed USD 2 million.In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalfof Det Norske Veritas.


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Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Pt.3 Ch.1 Page 3

DET NORSKE VERITAS AS

General

As of October 2010 all DNV service documents are primarily published electronically.

In order to ensure a practical transition from the print scheme to the electronic scheme, all rule chapters havingincorporated amendments and corrections more recent than the date of the latest printed issue, have been given the dateJanuary 2011.

An overview of DNV service documents, their update status and historical amendments and corrections may be foundthrough http://www.dnv.com/resources/rules_standards/.

Amendments July 2011

General

The restricted use legal clause found in Pt.1 Ch.1 Sec.4 has been added also on the front page.

Main changes

Since the previous edition (January 2005), this chapter has been amended, most recently in July 2010. All changespreviously found in Pt.0 Ch.1 Sec.3 have been incorporated and a new date (January 2011) has been given as explainedunder General.

In addition, the layout has been changed to one column in order to improve electronic readability.


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Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Amended July 2011, see page 3Pt.3 Ch.1 Contents Page 4


CONTENTS

Sec. 1 Design Principles ................................................................................................................................ 5

A. Documentation ..............................................................................................................................................................5A 100 Plans and particulars .............................................................................................................................................5

A 200 Information ........................................................................................................................................................... 5A 300 Strength calculations.............................................................................................................................................5A 400 Certificates............................................................................................................................................................5

B. Subdivision and Arrangement .....................................................................................................................................6B 100 General ..................................................................................................................................................................6B 200 Transverse watertight bulkheads........................................................................................................................... 6B 300 Position of collision bulkhead............................................................................................................................... 6B 400 Openings and closing appliances..........................................................................................................................6B 500 Cofferdams............................................................................................................................................................6B 600 Steering gear compartment ...................................................................................................................................7

C. Scantlings .......................................................................................................................................................................7C 100 General ..................................................................................................................................................................7

C 200 Loading conditions ............................................................................................................................................... 7C 300 Hull girder strength ............................................................................................................................................... 7C 400 Resistance to slamming ........................................................................................................................................7C 500 Local vibrations .................................................................................................................................................... 7C 600 Miscellaneous strength requirements.................................................................................................................... 7

D. Definitions ...................................................................................................................................................................... 7D 100 Symbols ................................................................................................................................................................ 7D 200 Structural terms..................................................................................................................................................... 8

Sec. 2 Design Loads..................................................................................................................................... 10

A. General.........................................................................................................................................................................10A 100 Introduction......................................................................................................................................................... 10A 200 Definitions .......................................................................................................................................................... 10

B. Accelerations................................................................................................................................................................11B 100 General ................................................................................................................................................................ 11B 200 Design vertical acceleration................................................................................................................................12B 300 Horizontal accelerations...................................................................................................................................... 13

C. Pressures and Forces ..................................................................................................................................................14C 100 General ................................................................................................................................................................ 14C 200 Slamming pressure on bottom ............................................................................................................................ 14C 300 Forebody side and bow impact pressure............................................................................................................. 16C 400 Slamming pressure on flat cross structures.........................................................................................................17C 500 Sea pressure ........................................................................................................................................................18C 600 Liquids ................................................................................................................................................................19C 700 Dry cargo, stores and equipment ........................................................................................................................20

C 800 Heavy units ......................................................................................................................................................... 20

Sec. 3 Hull Girder Loads............................................................................................................................ 21

A. Longitudinal Bending, Shearing and Axial Loads................................................................................................... 21A 100 General ................................................................................................................................................................ 21A 200 Crest landing .......................................................................................................................................................21A 300 Hollow landing ................................................................................................................................................... 22A 400 Hydrofoils ...........................................................................................................................................................22A 500 Hogging and sagging bending moments.............................................................................................................22A 600 Shear forces from longitudinal bending..............................................................................................................23A 700 Axial loads..........................................................................................................................................................23A 800 Combination of hull girder loads........................................................................................................................ 23

B. Twin Hull Loads..........................................................................................................................................................23

B 100 General ................................................................................................................................................................ 23B 200 Vertical bending moment and shear force ..........................................................................................................24B 300 Pitch connecting moment....................................................................................................................................26B 400 Twin hull torsional moment................................................................................................................................26


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Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Pt.3 Ch.1 Sec.1 Page 5


SECTION 1DESIGN PRINCIPLES

A. Documentation

A 100 Plans and particulars101 The following plans shall normally be submitted for approval:

midship section including main particulars (L, B, D, T, CB), maximum service speed V and design waveheight HS. (significant double amplitude)

profile and decks shell expansion and framing including openings watertight bulkheads and transom including openings and their closing appliances tank structures including height of air pipes engine room structures including tanks and foundations for heavy machinery components afterpeak structures forepeak structures superstructures and deckhouses including openings with sill heights and their closing appliances

hatchways, hatch covers, ports in crafts sides and ends including securing and tightening appliances propeller shaft brackets with their attachment to the hull trim flaps or foils with their attachment to the hull rudder and rudder stock with details of bearings arrangement and particulars of anchoring and mooring equipment with windlass drawings of cathodic protection systems, showing anode types, mass, distribution, location and attachment

details (for sacrificial anodes or impressed current anodes with reference electrodes) selection and combination of materials for exposure to sea water and/or marine atmosphere.

Identical or similar structures in various positions should preferably be covered by the same plan.

102 When relevant an operating manual shall be submitted, see Pt.1 Ch.1 Sec.2 A400.

103 The following plans shall be submitted for information:

general arrangement engine room arrangement tank arrangement capacity plan body plan, hydrostatic curves or tables specifications for corrosion protection, i.e. for coating, see Ch.3 Sec.2 C301 and for cathodic protection

including calculations, see Ch.3 Sec.2 C403.

104 Additional documentation required for approval are listed in the appropriate Parts.

A 200 Information

201 Information which may be necessary for longitudinal strength calculations shall be submitted.

202 Information which may be necessary for overall and local strength calculations shall be submitted.

A 300 Strength calculations

301 Strength calculations shall normally be submitted for reference demonstrating that stresses are withinrequired limits according to the rules.

302 For craft of novel design and for craft with L >50 m, global hull strength analysis demonstrating stressesand deflections in the hull structure will normally be required.

A 400 Certificates

401 Certificates issued by Det Norske Veritas will be required for the following materials/components:

all materials to be used in hull, superstructure and deckhouses

trim foils or flaps rudder and rudder stock steering gear anchor and chain/wire ropes windlass.


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Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Amended July 2011, see page 3Pt.3 Ch.1 Sec.1 Page 6


B. Subdivision and Arrangement

B 100 General

101 The hull shall be subdivided into watertight compartments as required for the service and type notationrequested.

B 200 Transverse watertight bulkheads

201 At least the following transverse watertight bulkheads shall be fitted in all craft:

a collision bulkhead a bulkhead at each end of the machinery space(s).

202 The watertight bulkheads are in general to extend to the freeboard deck. Afterpeak bulkheads may,however, terminate at the first watertight deck above the waterline at draught T.

203 For craft with two continuous decks and a large freeboard to the uppermost deck, the following applies:

when the draught is less than the depth to the second deck, only the collision bulkhead need extend to theuppermost continuous deck. The remaining bulkheads may terminate at the second deck

when the draught is greater than the depth to the second deck, the machinery bulkheads, with the exception

of afterpeak bulkhead, shall extend watertight to the uppermost continuous deck.

204 In craft with a raised quarter deck, the watertight bulkheads within the quarter deck region shall extendto this deck.

205 For craft with the additional class notationYacht and Patrol alternative arrangements may be acceptedbased on special considerations.

B 300 Position of collision bulkhead

301 The distance xc from the forward perpendicular to the collision bulkhead shall be taken between thefollowing limits:

xc(minimum) = 0.05 L (m)

xc(maximum) = 3.0 + 0.05 L (m)

L = length in m on design waterline.

302 Minor steps or recesses in the collision bulkhead may be accepted, provided the requirements tominimum and maximum distances from the forward perpendicular are complied with.

303 For craft having complete or long forward superstructures, the collision bulkhead shall extend to the nextdeck above freeboard deck. The extension need not be fitted directly over the bulkhead below, provided therequirements to distances from the forward perpendicular are complied with, and the part of the freeboard deckforming the step is made watertight.

For craft having particular high freeboard and long bow overhang, the position of the collision bulkhead abovethe freeboard deck may be specially considered.

304 For craft with the additional class notationYacht and Patrol alternative arrangements may be accepted

based on special considerations.B 400 Openings and closing appliances

401 Openings may be accepted in watertight bulkheads, except in that part of the collision bulkhead whichis situated below the freeboard deck.

402 Openings situated below the freeboard deck shall have watertight doors with signboards fitted at eachdoor stipulating that the door be kept closed while the craft is at sea. This assumption will be stated in theAppendix to Classification Certificate.

403 Openings in the collision bulkhead above the freeboard deck shall have weathertight doors or anequivalent arrangement. The number of openings in the bulkhead shall be reduced to the minimum compatiblewith the design and normal operation of the craft.

404 ForYacht and Patrol notation alternative requirements may apply.B 500 Cofferdams

501 Cofferdams Fuel oil, lubricating oil and fresh water tanks shall be separated from each other bycofferdams.


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B 600 Steering gear compartment

601 The steering gear compartment shall be readily accessible and, as far as practicable, separated frommachinery spaces.

C. Scantlings

C 100 General

101 Hull scantlings are in general to be based on the two design aspects, load and strength.

102 The rules have established design loads corresponding to the loads imposed by the sea and thecontainment of cargo, passengers, ballast and bunkers. The design loads are applicable in strength formulaeand calculation methods when satisfactory strength level is represented by allowable stress and/or usagefactors.

103 The structure shall be capable of withstanding the static and dynamic loads which can act on the craftunder operating conditions, without such loading resulting in inadmissible deformation and loss ofwatertightness or interfering with the safe operation of the craft.

104 Cyclic loads, including those from vibrations which can occur on the craft, shall not:

impair the integrity of structure during the anticipated service life of the craft hinder normal functioning of machinery and equipment impair the ability of the crew to carry out its duties.

105 Documentation on the vibration level onboard a craft may be required.

C 200 Loading conditions

201 Static loads are derived from loading conditions submitted by the builder or standard conditionsprescribed in the rules.

202 Wave-induced loads determined according to accepted theories, models tests or full scale measurementsmay be accepted as equivalent basis for classification. However, craft will not be classed for operation withina specific geographical area.

The determination of dynamic loads shall be based on long term distribution of responses that the craft willexperience during its operating life.

C 300 Hull girder strength

301 For craft with length L 50 m the minimum strength standard is normally satisfied for scantlingsobtained from local strength requirements.

C 400 Resistance to slamming

401 Craft shall be strengthened to resist slamming. Requirements for minimum slamming loads andassociated allowable stresses are given.

C 500 Local vibrations

501 The evaluation of structural response to vibrations caused by impulses from engine and propeller blades

is not covered by the classification.Upon request such evaluation may be undertaken by the Society.

C 600 Miscellaneous strength requirements

601 Requirements for scantlings of foundations, minimum plate thicknesses and other requirements notrelating relevant load and strength parameters may reflect criteria other than those indicated by these

parameters. Such requirements may have been developed from experience or represent simplificationsconsidered appropriate by the Society.

D. Definitions

D 100 Symbols101

L = length of the craft in m defined as the distance between perpendiculars. Amidships is defined as themiddle of L


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FP = forward perpendicular is the perpendicular at the intersection of the fully loaded waterline (with thecraft at rest) with the foreside of the stem

AP = after perpendicular is the perpendicular at the intersection of the fully loaded waterline (with the craftat rest) with the after side of sternpost or transom

B = greatest moulded breadth in m

D = moulded depth is the vertical distance in m from baseline to moulded deckline at the uppermostcontinuous deck measured amidships

T = fully loaded draught in m with the craft floating at rest in calm water

= fully loaded displacement in tonnes in salt water (density 1.025t/m3) on draught TCB = block coefficient, given by the formula:

=

BWL = greatest moulded breadth of the hull(s) in m at the fully loaded waterline (with the craft at rest).

For multihull craft BWL is the net sum of the waterline breadths

BWL2 = greatest moulded breadth of the hull(s) in m at the fully loaded waterline (with the craft at rest)measured at L/2.

For multihull craft BWL2 is the net sum of the waterline breadths

V = maximum speed in knots

g0 = standard acceleration of gravity.= 9.81 m/s2

LCG = longitudinal centre of gravity

WL = water line.

D 200 Structural terms

201 Freeboard deckis a deck above waterline, weathertight closed or protected, from which a freeboard ismeasured. For details see LL3 (Load Line Convention of 1966, Regulation 3).

202 Superstructure is defined as a decked structure on the freeboard deck, extending from side to side of theship or with the side plating not being inboard of the shell plating more than 4% of the breadth (B). See also

LL3.

203 Strength deckis normally defined as the uppermost continuous deck. A superstructure deck which within0.4L amidships has a continuous length equal to or greater than

or

shall be regarded as the strength deck instead of the covered part of the uppermost continuous deck.

H = height in m between the uppermost continuous deck and the superstructure deck in question.Another deck may be defined as the strength deck after special consideration of its effectiveness.

An analysis may be required to estimate the effective width of the various decks in the craft, and thereby theircontribution to the hull girder section modulus.

Strength deck requirements may then have to be applied to effective party of all upper decks.

204 Short superstructure deckis a superstructure deck which shall not be regarded as a strength deck.

205 Weather decks are open decks or parts of decks which may be exposed to local sea and weather loads.

206 Bulkhead deck (for passenger vessels and some special purpose vessels) is a deck above floodedwaterline to which the watertight bulkheads are carried.

207 Weathertightis used for external surfaces above freeboard (or bulkhead) deck and means that in any sea

conditions water will not penetrate into the ship.Flush with and below freeboard (or bulkhead) deck the stronger term watertightis used in the same meaning.

208 Watertightelsewhere is primarily related to the internal subdivision of the ship, and means that in aflooded condition water will not penetrate from one compartment into the other.

1 .025L BWLT-------------------------------------

3B

2---- H+

(m) for monohull vessels

3L

15------ H+

(m) for twin hull vessels


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A certain permanent set is, however, accepted in this one-accident case, which means that a watertight bulkheadis inferior to a tank bulkhead and is not accepted as such.

209 Girderis a collective term for primary supporting members, usually supporting stiffeners. Other termsused are:

bottom, side and deck transverses floor (a bottom transverse)

stringer (a horizontal girder) web frame vertical web.

210 Stiffeneris a collective term for a secondary supporting member. Other terms used are:

beam frame reversed frame (inner bottom transverse stiffeners) longitudinal.

211 Flat cross structure is a structure having an exposed, down-facing, horizontal or near-horizontalsurface above the waterline.

212 Supporting structure. Strengthening of the vessel structure, e.g. a deck, in order to accommodate loadsand moments from a heavy or loaded object.

213 Foundation. A device transferring loads from a heavy or loaded object to the vessel structure.


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SECTION 2DESIGN LOADS

A. General

A 100 Introduction101 Design loads given in this section are derived from full scale measurements and statistical analysis ofhigh speed and light craft designs.

102 Design loads given in this section covers:

High Speed and Light Craft (HSLC) which comply with the speed requirement in Pt.1 Ch.1 Sec.2 A104and A105; i.e. V 25 knots

Light Craft (LC) according to V < 25 knots.

103 New design concepts may require tank tests, theoretical studies, or full scale measurements to establishseakeeping properties and design loads.

104 Design pressures caused by sea, liquid cargoes, dry cargoes, ballast and bunkers are based on extremeconditions, but are modified to equivalent values corresponding to the stress levels stipulated in the rules.

105 The effects of speed reduction in heavy weather are allowed for. Limiting sea state (significant waveheight) to speed reduction may be stipulated. Such restrictions will be stated in the Appendix to ClassificationCertificate.

106 A signboard giving the relationship between allowable speed and significant wave height as restrictedshall be posted in the wheelhouse.

107 Significant wave height is the average of the 1/3 highest wave heights within the wave spectrum. Visualobservation of the wave height by an experienced person coincides well with the significant wave height.

108 Installation of an accelerometer at LCG may be required.

A 200 Definitions

201 Symbols:

p = design pressure in kN/m 2

= density of liquid or stowage rate of dry cargo in t/m3

Cw = wave coefficient.

For unrestricted service:

Cw = 0.08 L for L 100m= 6 + 0.02 L for L > 100m.

Reduction of Cw for restricted service is given in Table A1.

Restricted service class notations are defined in Pt.1 Ch.1 Sec.2.

Variation of wave coefficient Cw is shown in Fig.1.

Table A1 Reduction of Cw

Class notation Reduction

R0R1R2R3R4

R5-R6

0010%20%40%60%


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Fig. 1Wave coefficient

202 The load point for which the design pressure shall be calculated is defined for various strength membersas follows:

a) For plates: midpoint of horizontally stiffened plate.

Half of the stiffener spacing above the lower support of vertically stiffened plate, or at lower edge of platewhen the thickness is changed within the plate.

b) For stiffeners: midpoint of span.

When the pressure varies other than linearly the design pressure shall be taken as the greater of:

pm pa and pb are calculated pressure at the midpoint and at each end respectively.

c) For girders: midpoint of load area.

B. AccelerationsB 100 General

101 Accelerations in the crafts vertical, transverse and longitudinal axes are in general obtained by assumingthe corresponding linear acceleration and relevant components of angular accelerations as statisticallyindependent variables. The combined acceleration in each direction may be taken as:

n = number of independent variables.

Transverse or longitudinal component of the angular acceleration considered in the above expression shallinclude the component of gravity acting simultaneously in the same direction.

102 The combined effects given in the following may deviate from the above general expression due topractical simplifications applicable to hull structural design or based on experience regarding phasing betweencertain basic components.

pm andpa pb+

2-----------------

ac am2

m 1=

n

=


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B 200 Design vertical acceleration

201 Design vertical acceleration at crafts centre of gravity acg shall be specified by the builder, and isnormally not to be less than:

Minimum acg= 1 g0 for service restriction R0-R4

Minimum acg= 0.5 g0 for service restriction R5

fg = acceleration factor (fraction of g0) dependent of type and service notation and service area restrictionnotation given in Table B1.

The design vertical acceleration is an extreme value with a 1% probability of being exceeded, in the worstintended condition of operation.

202 Unless otherwise established, the design acceleration at different positions along the crafts length shallnot be less than:

kv = longitudinal distribution factor taken from Fig.2.

203 The allowable speed corresponding to the design vertical acceleration acg, may be estimated from theformulas for the relationship between instantaneous values of acg, V and Hs, given in 204 and 205.

204

Hs = significant wave height in mcg = deadrise angle at LCG in degrees

= minimum 10= maximum 30

BWL2 = water line breadth at L/2 in m.

For twin- and multi hull vessels the total breadth of the hulls (exclusive tunnels) shall be used

g0 = standard acceleration of gravity = 9.81 m/s2

kh = hull type factor given in Table B2.

Table B1 Acceleration factor fg

Type and servicenotation

Service area restriction notation

R0 R1 R2 R3 R4 R5-R6

Passenger 1) 1 1 1 1 0.5

Car ferry 1) 1 1 1 1 0.5

Cargo 4 3 2 1 1 0.5

Patrol 7 5 3 1 1 0.5

Yacht 1 1 1 1 1 0.5

1) Service area restriction R0 is not available for class notations Passengerand Car Ferry.

Table B2 Hull type factor

Hull type khMonohull, Catamaran 1.0

Wave Piercer 0.9

SES, ACV 0.8

Foil assisted hull (see 206) 0.7

SWATH (see 206) 0.7

acgV

L-------

3.2

L0.76

-------------fg g0 m s2

( ).=

V

L------- need not be taken greater than 3,0

av kv acg=

hen V L 3:

acg

khg0

1650------------

HS

BWL 2-------------- 0.084+

50 cg( )

V

L-------

2 L BWL 2

2

------------------------- m s

2( )

=


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The hull type factor kh is an estimate for correction of the vertical acceleration depending on the different typesof hull forms.

205

206 Unless other values are justified by calculations according to accepted theories, model tests or full scalemeasurements, the speed reductions implied by 204 and 205 shall be applied. For SWATH and craft with foilassisted hull, accelerations shall normally be determined in accordance with the above direct methods.

207 Relationships between allowable speed and significant wave height will be stated in the Appendix toClassification Certificate.

Fig. 2Longitudinal distribution factor for vertical design acceleration

B 300 Horizontal accelerations

301 The craft shall be designed for a longitudinal (surge) acceleration not less than

Tentative formula for the relation between instantaneous values of al, HS and V:

al is intended for calculation of forward directed inertia forces and may have to be increased based on theoverall impact possibilities in crafts front.

almay be simultaneous with downward vertical inertia in forebody.

302 It may be necessary to pay attention to transverse acceleration from forced roll in bow seas.

Period of forced roll to be taken:

When V L 3: 50m

a v = as given in B200

hs = vertical distance in m from the load point to the top of tank

hp = vertical distance in m from the load point to the top of air pipe or filling station.

For tanks which may be filled to top of air pipe or filling station and subsequently subjected to accelerations,the pressure shall be modified accordingly.

603 The design pressure on wash bulkheads is given by:

p = 3.5 lt (kN/m2)

lt = the greater distance in m to the next bulkhead forward or aft.

For wash bulkhead plating, requirement to thicknesses may have to be based on the reaction forces imposed onthe bulkhead by boundary structures.

C 700 Dry cargo, stores and equipment

701 The pressure on inner bottom, decks or hatch covers shall be taken as:

p =H (g0

+ 0.5 av) (kN/m2)

av = as given in B200

H = stowage height in m.

Standard values ofand H are given in Table C2.

If decks (excluding inner bottom) or hatch covers are designed for cargo loads heavier than the standard loadsgiven in Table C2, the notation dk (+) orha (+), respectively, will be entered in the Register of Ships. Thedesign cargo load in t/m2 will be given for each individual cargo space in the Appendix to ClassificationCertificate.

702 When the weather deck or weather deck hatch covers are designed to carry deck cargo, the pressure is ingeneral to be taken as the greater of p according to 500 and 700.

703 For transverse bulkheads in way of general cargo holds, the design loads given for watertight bulkheads

apply.

C 800 Heavy units

801 Heavy units The vertical force acting on supporting structures from rigid units of cargo, equipment orother structural components shall normally be taken as:

Pv = (g0 + 0.5 av) M (kN)

M = mass of unit in tonnes

av = as given in B200.

Table C2 Standard load parameters

Decks Parameters

Weather deck and weather deck hatchcovers intended for cargo

H = 1.0 t/m2

Sheltered deck, sheltered hatch coversand inner bottom for cargo or stores

= 0.7 t/m3

H = vertical distance in m from the load point to the deck above. For loadpoints below hatchways H shall be measured to the top of coaming

Platform deck in machinery space H = 1.6 t/m2

Accommodation decksH = 0.35 t/m2, when not directly calculated, including the deck's own mass.Minimum 0.25 t/m2.


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SECTION 3HULL GIRDER LOADS

A. Longitudinal Bending, Shearing and Axial Loads

A 100 General101 For craft of ordinary hull form with L/D less than 12 and with length less than 50 m, the minimumstrength standard is normally satisfied for scantlings obtained from local strength requirements.

102 For other types of craft, craft with L/D greater than 12 and for craft with length greater than 50 m, thelongitudinal strength shall be calculated as described in the following.

A 200 Crest landing

201 For craft with a slamming pressure is acting on an area equal to the reference area, AR,given below. The area shall be situated with the load point at LCG of the craft. The weight distribution of thehull girder shall be increased by the acceleration at LCG. The hull girder shall be considered out of water.

where:

k = 0.7 for crest landing= 0.6 for hollow landing.

202 The load combination which is illustrated in Fig.1 may be required analysed with actual weightdistribution along the hull beam.

203 The longitudinal midship bending moment may be assumed to be:

= displacement in tonnesacg = vertical design acceleration at LCG

ew = one half of the distance from LCG of the fore half body to the LCG of the aft half body of the vessel, in m= 0.25 L if not known (0.2 L for hollow landing)

ls = longitudinal extension of slamming reference area:

where bs is the breadth of the slamming reference area. See Fig.2.

(ew - ls/4) shall not be taken less than 0.04 L.

204 The reduction of MB towards ends will be determined by the weight distribution and the extent of AR.

Fig. 1Crest landing

Fig. 2Breadth of midship slamming reference area

V L 3

AR k

1 0.2acg

g0

-------+

T------------------------------- m2

( )=

MB

2--- g0 acg+( ) ew

ls

4---

kNm( )=

ls

AR

bs-------=


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Fig. 3

Hollow landing

A 300 Hollow landing

301 Hollow landing is similar to crest landing except that the reference area ARis situated towards AP andFP as shown in Fig.3.

302 The load combination may be required analysed with actual weight distribution along the hull beam.

303 The longitudinal midship bending moment may be assumed to be:

er

= mean distance from the centre of the AR

/2 end areas to the vessels LCG in m.

(er ew) not to be taken less than 0.04 L

A 400 Hydrofoils

401 The calculation of longitudinal strength of hydrofoils shall be effected for the most severe condition. Asa rule this will be considering the craft sustained above the water surface by the foils and supposing it to bestationary in the navigation condition, taking into account vertical acceleration as well as the verticalcomponents of the hydrodynamic action of the water on the foils.

A 500 Hogging and sagging bending moments

501 For all craft an investigation of hogging and sagging bending moments taking into account anyimmersed/ emerged structures may be required.

502 The investigation is in its simplest form to be based on a predicted phasing between pitch/heave and thepassage of a meeting design wave, and shall include the pitch angle and the inertia forces to be expected in thehogging and sagging conditions.

503 Tentative formulae for bending moments (still water + wave) for high speed light craft:

For monohull craft (in kNm):

Mtot hog = Msw + 0.19 CW L2 B CB

Mtot sag = Msw + 0.14 CW L2 B (CB + 0.7)

Msw= still water moment in the most unfavourable loading condition in kNm1)

= 0.11 Cw L2 B CB (kNm) in hogging if not known

= 0 in sagging if not known. 2)

For twin hull craft (in kNm):

Mtot hog = Msw + 0.19 CW L2 (BWL2 + k2 Btn) CB

Mtot sag = Msw + 0.14 CW L2 (BWL2 + k3 Btn) (CB + 0.7)

Msw = still water moment in the most unfavourable loading condition in kNm1)

= 0.5 L (kNm) in hogging if not known= 0 in sagging if not known. 2).

Additional correction of 20% to be added to the wave sagging moment for craft with large flare in the foreship.

1) Documentation of the most unfavourable still water conditions shall normally be submitted for information.

2) If the still water moment is a hogging moment, 50% of this moment can be deducted where the design sagging moment Mtotsag is

calculated.

Btn = breadth in m of cross structures (tunnel breadth)

k2 and k3 = empirical factors for the effect of cross structure immersion in hogging and sagging waves. If noother value available:

MB

2--- g0 acg+( ) er ew( )=


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k4 = 0.25 in general, when V is maximum speed of craft,= 0.35 when V is taken as the slowed down speed

z = height in m from base line to wet deck (top of tunnel).

A 600 Shear forces from longitudinal bending

601 A vertical hull girder shear force may be related to the hull girder bending moments from 200, 300, and500 as follows:

MB = bending moment in kNm.

A 700 Axial loads

701 Axial loads from

surge = al thrust and sea end pressures

may have to be estimated and added together in most exposed areas (forebody buckling control).

al = maximum surge acceleration, not to be taken less than:

with linear interpolation for intermediate .

A 800 Combination of hull girder loads

801 The hull girder loads vertical bending, vertical shear and torsion (B400) shall be considered accordingto the following combinations:

80% longitudinal bending and shear + 60% torsion 60%% longitudinal bending and shear + 80% torsion.

802 The hull girder loads transverse vertical bending moment (B200) and pitch connecting moment (B300)shall be considered according to the following combinations:

70% transverse bending + 100% pitch connecting 100% transverse bending + 70% pitch connecting.

B. Twin Hull Loads

B 100 General

101 The transverse strength of twin hull connecting structure may be analysed for moments and forcesspecified below.

102 Design forces and moments given in 200, 300 and 400 shall be used unless other values are verified bymodel tests or full scale measurements or if similar structures have proved to be satisfactory in service.

k2 1z 0.5 T

0.5 T 2 CW+--------------------------------- , minimum 0=

k3 1z 0.5 T

0.5 T 2.5 CW+-------------------------------------- , minimum 0=

Qb

MB

0 .25 L----------------- (kN)=

0.4 g0 fo rV

L------- 5

0.2( ) g0 fo rV

L------- 3

V L


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B 200 Vertical bending moment and shear force

201 For craft with and L < 50 m, the twin hull transverse bending moment may be assumed to be:

b = transverse distance between the centrelines of the two hulls

s = factor given in Table B1.

Fig. 4Transverse vertical bending moment and shear force

202 For craft with L 50 m the twin hull transverse bending moment shall be assumed to be the greater of:

MS0 = still water transverse bending moment in kNm

Fy = horizontal split force on immersed hull

H1 =

BWL = maximum width (m) in water line (sum of both hulls)

BMAX = maximum width (m) of submerged part (sum of both hulls)

LBMAX = length in metres where BMAX/BWL > 1

HS,MAX = maximum significant wave height in which the vessel is allowed to operate (m)B = beam over all (m)

z = height from base line to neutral axis of cross structure (m).

See Fig.5 for explanation of symbols. The expression should not be used for Surface Effect Ships (SES) incushion borne mode, but shall be applied to SES in a survival condition with cushion air pressure equal to zero.A reduction factor of 0.8 is then to be applied to the dynamic split moment.

need not be taken greater than 3

V L 3( )

MS

acgb

s----------------- (kNm)=

MS MS0 1acg

g0-------+

(kNm)=

MS MS0 Fy z 0.5T( ) (kNm)+=

3.25 1 0.0172 VL

-------+ L1.05T1.30 0.5 BWL( )0.146

1LBMAX

L-------------------

LBMAX

L-------------------

BMAX

BWL----------------

2.10

+ H1 (kN)

=

min0.143B

HS MAX,

V

L-------


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Fig. 5Definition of parameters in case of different sectional shapes

203 The vertical shear force in centreline between twin hull may be assumed to be:

q = factor given in Table B1.

204 For craft with length L 50 m the twin hull still water transverse bending moment shall be assumed to be:

MS0 = still water transverse bending moment

D = displacement in tonnes

yb = distance in m from centre line to local centre line of one hull (see Fig.6 for definition)B = width over all in m.

Fig. 6Definition of local geometry for one hull on twin hull craft

Table B1 Factors s and q

Service restriction s qR4-R6

R3R2R1R0

8.07.56.55.54.0

6.05.55.04.03.0

0.5BWL=0.5BMAX 0.5BWL 0.5BWL

0.5BMAX 0.5BMAX

LB MAX

S a cg

q-------------- (kN)=

MS0 4.91 yb 0.4 B0.88

( ) (kNm)=

yb


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The expression shall not be used for Surface Effect Ships (SES) or for twin hulls with significant weight alongthe centre line.

B 300 Pitch connecting moment

301 The twin hull pitch connection moment (see Fig.7) may be assumed to be:

Fig. 7Pitch connecting moment and torsion moment on twin hull connection

B 400 Twin hull torsional moment

401 Hull torsional moment of twin hull may be assumed to be:

b = distance in m between the two hull centerlines.

MP

a cg L

8------------------ (kNm)=

Mt

a cgb

4----------------- (kNm)=


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RULES FOR CLASSIFICATION OF

DETNORSKEVERITASAS

The content of this service document is the subject of intellectual property rights reserved by Det Norske Veritas AS (DNV). The useraccepts that it is prohibited by anyone else but DNV and/or its licensees to offer and/or perform classification, certification and/orverification services, including the issuance of certificates and/or declarations of conformity, wholly or partly, on the basis of and/orpursuant to this document whether free of charge or chargeable, without DNV's prior written consent. DNV is not responsible for theconsequences arising from any use of this document by others.

High Speed, Light Craft and NavalSurface Craft

PART 3 CHAPTER 3

STRUCTURES, EQUIPMENT

Hull Structural Design,Aluminium Alloy

JANUARY 2011

This chapter has been amended since the main revision (January), most recently in July 2011.

See Changes on page 3.


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FOREWORD

DET NORSKE VERITAS (DNV) is an autonomous and independent foundation with the objectives of safeguarding life,property and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification andconsultancy services relating to quality of ships, offshore units and installations, and onshore industries worldwide, andcarries out research in relation to these functions.

The Rules lay down technical and procedural requirements related to obtaining and retaining a Class Certificate. It is usedas a contractual document and includes both requirements and acceptance criteria.

The electronic pdf version of this document found through http://www.dnv.com is the officially binding version Det Norske Veritas AS January 2011

Any comments may be sent by e-mail to [email protected] subscription orders or information about subscription terms, please use [email protected]

Computer Typesetting (Adobe Frame Maker) by Det Norske Veritas

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of Det Norske Veritas, then Det Norske Veritas shall pay compensation tosuch person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to ten times the fee charged for the service in question, provided thatthe maximum compensation shall never exceed USD 2 million.In this provision "Det Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all its subsidiaries, directors, officers, employees, agents and any other acting on behalfof Det Norske Veritas.


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Rules for High Speed, Light Craft and Naval Surface Craft, January 2011Pt.3 Ch.3 Changes Page 3


CHANGES

General

As of October 2010 all DNV service documents are primarily published electronically.

In order to ensure a practical transition from the print scheme to the electronic scheme, all rule chapters havingincorporated amendments and corrections more recent than the date of the latest printed issue, have been given the dateJanuary 2011.

An overview of DNV service documents, their update status and historical amendments and corrections may be foundthrough http://www.dnv.com/resources/rules_standards/.

Amendments July 2011

General

The restricted use legal clause found in Pt.1 Ch.1 Sec.4 has been added also on the front page.

Main changes

Since the previous edition (July 2000), this chapter has been amended, most recently in January 2006. All changespreviously found in Pt.0 Ch.1 Sec.3 have been incorporated and a new date (January 2011) has been given as explainedunder General.

In addition, the layout has been changed to one column in order to improve electronic readability.


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CONTENTS

Sec. 1 Structural Principles .......................................................................................................................... 8

A. General...........................................................................................................................................................................8A 100 The scantling reduction.........................................................................................................................................8

A 200 Aluminium alloys .................................................................................................................................................8B. Bottom Structures .........................................................................................................................................................8B 100 Longitudinal stiffeners.......................................................................................................................................... 8B 200 Web frames........................................................................................................................................................... 8B 300 Longitudinal girders.............................................................................................................................................. 8B 400 Engine girders.......................................................................................................................................................8B 500 Double bottom, if fitted ........................................................................................................................................9

C. Side Structure................................................................................................................................................................9C 100 Stiffeners...............................................................................................................................................................9

D. Deck Structure...............................................................................................................................................................9D 100 Longitudinal stiffeners.......................................................................................................................................... 9D 200 Bulwarks ............................................................................................................................................................... 9

E. Flat Cross Structure......................................................................................................................................................9E 100 Definition ..............................................................................................................................................................9E 200 Longitudinal stiffeners.......................................................................................................................................... 9

F. Bulkhead Structures ...................................................................................................................................................10F 100 Transverse bulkheads..........................................................................................................................................10F 200 Corrugated bulkheads .........................................................................................................................................10

G. Superstructures and Deckhouses............................................................................................................................... 10G 100 Definitions .......................................................................................................................................................... 10G 200 Structural continuity ...........................................................................................................................................10

H. Structural Design in General .....................................................................................................................................11H 100 Craft arrangement ............................................................................................................................................... 11H 200 Soft local transitions ...........................................................................................................................................11

H 300 Impact strength ................................................................................................................................................... 11I. Some Common Local Design Rules...........................................................................................................................11I 100 Definition of span ...............................................................................................................................................11I 200 Effective girder flange ........................................................................................................................................ 12I 300 Sniped stiffeners .................................................................................................................................................13

J. Support of Equipment and Outfitting Details .......................................................................................................... 13J 100 Heavy equipment, appendages etc......................................................................................................................13J 200 Minor outfitting details.......................................................................................................................................13

K. Structural Aspects not Covered by Rules ................................................................................................................. 13K 100 Deflections.......................................................................................................................................................... 13K 200 Local vibrations ..................................................................................................................................................14

Sec. 2 Materials and Material Protection ................................................................................................. 15

A. General.........................................................................................................................................................................15A 100 Application..........................................................................................................................................................15A 200 Material certificates ............................................................................................................................................15

B. Structural Aluminium Alloy ......................................................................................................................................15B 100 General ................................................................................................................................................................ 15B 200 Aluminium grades...............................................................................................................................................15B 300 Chemical composition ........................................................................................................................................ 15B 400 Mechanical properties.........................................................................................................................................15

C. Corrosion Protection...................................................................................................................................................17C 100 General ................................................................................................................................................................ 17C 200 For information and approval .............................................................................................................................17C 300 Coating................................................................................................................................................................17

C 400 Cathodic protection.............................................................................................................................................18C 500 Other materials in contact with aluminium.........................................................................................................19

D. Other Materials ...........................................................................................................................................................19D 100 Steel .................................................................................................................................................................... 19D 200 Connections between steel and aluminium......................................................................................................... 19


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Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Pt.3 Ch.3 Contents Page 5


D 300 Fibre Reinforced Plastic (FRP)........................................................................................................................... 19

Sec. 3 Manufacturing.................................................................................................................................. 20

A. General.........................................................................................................................................................................20A 100 Basic requirements.............................................................................................................................................. 20

B. Inspection.....................................................................................................................................................................20

B 100 General ................................................................................................................................................................ 20B 200 Penetrant testing..................................................................................................................................................20B 300 Radiographic testing ...........................................................................................................................................20B 400 Ultrasonic examination.......................................................................................................................................20

C. Extent of Examination ................................................................................................................................................20C 100 General ................................................................................................................................................................ 20

D. Acceptance Criteria for NDT.....................................................................................................................................20D 100 Acceptance criteria.............................................................................................................................................. 20

E. Testing ..........................................................................................................................................................................21E 100 Tanks...................................................................................................................................................................21E 200 Closing appliances .............................................................................................................................................. 21

Sec. 4 Hull Girder Strength........................................................................................................................ 22


B. Vertical Bending Strength..........................................................................................................................................22B 100 Hull section modulus requirement......................................................................................................................22B 200 Effective section modulus...................................................................................................................................22B 300 Hydrofoil on foils................................................................................................................................................ 23B 400 Longitudinal structural continuity ...................................................................................................................... 23B 500 Openings .............................................................................................................................................................23

C. Shear Strength.............................................................................................................................................................24C 100 Cases to be investigated......................................................................................................................................24

D. Cases to be Investigated.............................................................................................................................................. 24D 100 Inertia induced loads........................................................................................................................................... 24

E. Transverse Strength of Twin Hull Craft...................................................................................................................24E 100 Transverse strength ............................................................................................................................................. 24E 200 Allowable stresses .............................................................................................................................................. 25

Sec. 5 Plating and Stiffeners....................................................................................................................... 26

A. General.........................................................................................................................................................................26A 100 Introduction......................................................................................................................................................... 26A 200 Definitions .......................................................................................................................................................... 26A 300 Allowable stresses...............................................................................................................................................26

B. Plating ..........................................................................................................................................................................26B 100 Minimum thicknesses .........................................................................................................................................26

B 200 Bending............................................................................................................................................................... 27B 300 Slamming ............................................................................................................................................................27

C. Stiffeners ......................................................................................................................................................................28C 100 Bending............................................................................................................................................................... 28C 200 Slamming ............................................................................................................................................................29

Sec. 6 Web Frames and Girder Systems................................................................................................... 30

A. General.........................................................................................................................................................................30A 100 Introduction......................................................................................................................................................... 30A 200 Definitions .......................................................................................................................................................... 30A 300 Minimum thicknesses .........................................................................................................................................30A 400 Allowable stresses...............................................................................................................................................31A 500 Continuity of strength members .........................................................................................................................31

B. Web Frames and Girders ...........................................................................................................................................31B 100 General ................................................................................................................................................................ 31B 200 Effective flange................................................................................................................................................... 31B 300 Effective web ......................................................................................................................................................32B 400 Strength requirements .........................................................................................................................................32


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B 500 Girder tripping brackets ......................................................................................................................................33B 600 Girder web stiffeners........................................................................................................................................... 34

Sec. 7 Pillars and Pillar Bulkheads............................................................................................................ 35


B. Pillars............................................................................................................................................................................35B 100 Arrangement of pillars........................................................................................................................................ 35B 200 Cross-section particulars..................................................................................................................................... 35B 300 Pillar scantlings...................................................................................................................................................35B 400 Pillars in tanks.....................................................................................................................................................36

C. Supporting Bulkheads ................................................................................................................................................37C 100 General ................................................................................................................................................................ 37

Sec. 8 Weld Connections............................................................................................................................. 38

A. General.........................................................................................................................................................................38A 100 Introduction......................................................................................................................................................... 38A 200 Welding particulars............................................................................................................................................. 38

B. Types of Welded Joints...............................................................................................................................................38B 100 Butt joints............................................................................................................................................................38B 200 Tee or cross joints ...............................................................................................................................................38

C. Size of Connections .....................................................................................................................................................39C 100 Fillet welds, general ............................................................................................................................................39C 200 Fillet welds and penetration welds subject to high tensile stresses .................................................................... 39C 300 End connections of girders, pillars and cross ties............................................................................................... 40C 400 End connections of stiffeners.............................................................................................................................. 40

Sec. 9 Direct Strength Calculations ........................................................................................................... 43

A. General.........................................................................................................................................................................43A 100 Introduction......................................................................................................................................................... 43A 200 Application..........................................................................................................................................................43

B. Plating ..........................................................................................................................................................................43B 100 General ................................................................................................................................................................ 43B 200 Calculation procedure .........................................................................................................................................43B 300 Allowable stresses...............................................................................................................................................43

C. Stiffeners ......................................................................................................................................................................43C 100 General ................................................................................................................................................................ 43C 200 Calculation procedure .........................................................................................................................................44C 300 Loads...................................................................................................................................................................44C 400 Allowable stresses...............................................................................................................................................44

D. Girders .........................................................................................................................................................................44D 100 General ................................................................................................................................................................ 44D 200 Calculation methods ...........................................................................................................................................44D 300 Design load conditions........................................................................................................................................ 44D 400 Allowable stresses...............................................................................................................................................45

Sec. 10 Buckling Control .............................................................................................................................. 46

A. General.........................................................................................................................................................................46A 100 Definitions .......................................................................................................................................................... 46

B. Longitudinal Buckling Load ......................................................................................................................................47B 100 Longitudinal stresses........................................................................................................................................... 47

C. Transverse Buckling Load .........................................................................................................................................47C 100 Transverse stresses..............................................................................................................................................47

D. Plating .......................................................................................................................................................................... 47D 100 Plate panel in uni-axial compression ..................................................................................................................47

D 200 Plate panel in shear ............................................................................................................................................. 49D 300 Plate panel in bi-axial compression and shear....................................................................................................49

E. Stiffeners in Direction of Compression ..................................................................................................................... 50E 100 Lateral buckling mode ........................................................................................................................................ 50E 200 Torsional buckling mode ....................................................................................................................................51


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Amended July 2011, see page 3 Rules for High Speed, Light Craft and Naval Surface Craft, January 2011 Pt.3 Ch.3 Contents Page 7


E 300 Web and flange buckling ....................................................................................................................................52

F. Stiffeners Perpendicular to Direction of Compression............................................................................................52F 100 Moment of inertia of stiffeners ...........................................................................................................................52

G. Elastic Buckling of Stiffened Panels ..........................................................................................................................53G 100 Elastic buckling as a design basis .......................................................................................................................53G 200 Allowable compression....................................................................................................................................... 53

H. Girders .........................................................................................................................................................................54H 100 Axial load buckling............................................................................................................................................. 54H 200 Girders perpendicular to direction of compression............................................................................................. 54H 300 Buckling of effective flange................................................................................................................................54H 400 Shear buckling of web ........................................................................................................................................ 55


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SECTION 1STRUCTURAL PRINCIPLES

A. General

A 100 The scantling reduction101 The scantling reductions for high speed and light craft structures compared with Rules for Classificationof Ships are based on:

longitudinal framing in bottom and strength deck extended longitudinal and local buckling control

a sea and weather service restriction.A 200 Aluminium alloys

201 The alloy grades are listed in Sec.2 Tables B1 to B4.

202 The various formulae and expressions involving the factor f1 may be applied when:

f = yield stress is not to be taken greater than 70% of the ultimate tensile strength.

The material factor f1 included in the various formulae and expressions is given in Sec.2 Tables B1 to B3 forthe un-welded condition and in Table B4 for the welded condition.

B. Bottom Structures

B 100 Longitudinal stiffeners

101 Single bottoms as well as double bottoms are normally to be longitudinally stiffened.

102 The longitudinals should preferably be continuous through transverse members. If they are to be cut attransverse members, i.e. watertight bulkheads, continuous brackets connecting the ends of the longitudinals areto be fitted or welds are to be dimensioned accordingly.

103 Longitudinal stiffeners are to be supported by bulkheads and web frames.

104 Longitudinal stiffeners in slamming areas should have a shear connection to transverse members.

B 200 Web frames

201 Web frames are to be continuous around the cross section i.e. floors side webs and deck beams are to beconnected. Intermediate floors may be used.

202 In the engine room plate floors are to be fitted at every frame. In way of thrust bearings additionalstrengthening is to be provided.

B 300 Longitudinal girders

301 Web plates of longitudinal girders are to be continuous in way of transverse bulkheads.

302 A centre girder is normally to be fitted for docking purposes.

303 Manholes or other openings should not be positioned at ends of girders without due consideration being

taken of shear loadings.B 400 Engine girders

401 Under the main engine, girders extending from the bottom to the top plate of the engine seating are to befitted.

s = chosen spacing in m

sr =

a certain stiffener spacing reduction ratios

sr

----

basic spacing =2 100 L+( )

1000--------------------------- m in general

f1

f240---------=


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402 Engine holdingdown bolts are to be arranged as near as practicable to floors and longitudinal girders.

403 In way of thrust bearing and below pillars additional strengthening is to be provided.

B 500 Double bottom, if fitted

501 Manholes are to be cut in the inner bottom, floors and longitudinal girders to provide access to all partsof the double bottom. The vertical exte

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