dnv ships for navigation in ice

7/22/2019 DNV Ships for Navigation in Ice

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RULES FORCLASSIFICATION OF

DETNORSKEVERITAS

Veritasveien 1, NO-1322 Hvik, Norway Tel.: +47 67 57 99 00 Fax: +47 67 57 99 11

SHIPS

NEWBUILDINGS

SPECIAL SERVICE AND TYPEADDITIONAL CLASS

PART 5 CHAPTER 1

SHIPS FOR NAVIGATION IN ICEJANUARY 2005This booklet includes the relevant amendments and corrections

shown in the July 2005 version of Pt.0 Ch.1 Sec.3.

CONTENTS PAGE

Sec. 1 General Requirements ................................................................................................................ 5Sec. 2 Basic Ice Strengthening.............................................................................................................. 6Sec. 3 Ice Strengthening for the Northern Baltic .................................................................................. 8

Sec. 4 Vessels for Arctic and Ice Breaking Service ........................................................................... 19Sec. 5 Sealers ..................................................................................................................................... 37


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CHANGES IN THE RULES

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Det Norske Veritas

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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 to such personfor 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 that the maximum compen-sation 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 behalf of DetNorske Veritas.

General

The present edition of the rules includes additions and amendmentsdecided by the Board as of November 2004 and supersedes the Janu-ary 2003 edition of the same chapter.

The rule changes come into force 1 July 2005.

This chapter is valid until superseded by a revised chapter. Supple-

ments will not be issued except for minor amendments and an updatedlist of corrections presented in Pt.0 Ch.1 Sec.3. Pt.0 Ch.1 is normallyrevised in January and July each year.

Revised chapters will be forwarded to all subscribers to the rules.Buyers of reprints are advised to check the updated list of rule chap-ters printed in Pt.0 Ch.1 Sec.1 to ensure that the chapter is current.

Main changes

Sec.4 Vessels for Arctic and Ice Breaking Service

This section has been revised in order to align the intact and damagestability requirements for the class notations Icebreakerand Polarwith those of the IMO MSC/Circ 1056 "Guidelines for Ships Operat-ing in Arctic Ice-covered waters" relevant for polar classes 1 to 3. Themain changes are:

Ice loads to be accounted for in the calculation of loading condi-tions.

Beaching stability no longer considered. Extent of assumed bottom and side damage generally reduced.

Corrections and Clarifications

In addition to the above stated rule requirements, a number of correc-tions and clarifications have been made in the existing rule text.


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Amended, Rules for Ships, January 2005see Pt.0 Ch.1 Sec.3, July 2005 Pt.5 Ch.1 Contents Page 3

DETNORSKEVERITAS

CONTENTS

SEC. 1 GENERAL REQUIREMENTS .......................... 5

A. Classification..........................................................................5A 100 Application........................................................................5

A 200 Class notations ..................................................................5

B. Definitions ..............................................................................5B 100 Symbols.............................................................................5B 200 Terms ................................................................................5

C. Documentation ......................................................................5C 100 General ..............................................................................5

SEC. 2 BASIC ICE STRENGTHENING ....................... 6

A. General ...................................................................................6A 100 Classification.....................................................................6

B. Hull Arrangement and Scantlings.......................................6B 100 Shell plating ......................................................................6B 200 Ordinary frames ................................................................6

B 300 Intermediate ice frames.....................................................6B 400 Ice stringer.........................................................................6B 500 Weld connections..............................................................6B 600 Sternframe and rudder ......................................................6

C. Machinery ..............................................................................7C 100 Output of propulsion machinery.......................................7C 200 Design of propeller and propeller shaft ............................7C 300 Sea suctions and discharges..............................................7

SEC. 3 ICE STRENGTHENING FOR THENORTHERN BALTIC ......................................... 8

A. General ...................................................................................8A 100 Classification.....................................................................8A 200 Assumptions......................................................................8

A 300 Definitions.........................................................................8A 400 Documentation..................................................................8

B. Design Loads .........................................................................9B 100 Height of load area............................................................9B 200 Ice pressure .......................................................................9

C. Shell Plating ...........................................................................9C 100 Vertical extension of ice strengthening.............................9C 200 Plate thickness in the ice belt ..........................................10

D. Frames..................................................................................10D 100 Vertical extension of ice framing....................................10D 200 Transverse frames ...........................................................10D 300 Longitudinal frames........................................................11D 400 Structural details .............................................................11

E. Ice Stringers ........................................................................12E 100 Stringers within the ice belt ............................................12E 200 Stringers outside the ice belt ...........................................12E 300 Deck strips ......................................................................12

F. Web Frames........................................................................12F 100 Design load .....................................................................12F 200 Section modulus and shear area ......................................12

G. Bilge Keels............................................................................13G 100 Arrangement....................................................................13

H. Special Arrangement and Strengthening Forward..........13H 100 Stem, baltic ice strengthening .........................................13H 200 Arrangements for towing................................................13

I. Special Arrangement and Strengthening Aft...................14

I 100 Stern ................................................................................14I 200 Rudder and steering arrangements .................................14

J. Machinery............................................................................14J 100 Engine output..................................................................14J 200 Design loads for propeller and shafting..........................16

J 300 Propeller..........................................................................16J 400 Shafting ...........................................................................17J 500 Thrust bearing and reduction gear .................................17J 600 Miscellaneous machinery requirements..........................18

SEC. 4 VESSELS FOR ARCTIC AND ICE BREAKINGSERVICE ........................................................... 19

A. General ................................................................................ 19A 100 Classification ..................................................................19A 200 Scope...............................................................................19A 300 Design principles and assumptions.................................19A 400 Definitions.......................................................................20A 500 Documentation................................................................21

B. Materials and Corrosion Protection................................. 22B 100 Design temperatures........................................................22B 200 Structural categories........................................................23B 300 Selection of steel grades..................................................23B 400 Coatings ..........................................................................24B 500 Corrosion additions.........................................................24B 600 Equipment.......................................................................24

C. Ship Design and Arrangement.......................................... 24C 100 Hull form.........................................................................24C 200 Appendages.....................................................................24C 300 Mooring equipment.........................................................24

D. Design Loads ...................................................................... 24D 100 Ice impact forces on the bow..........................................24D 200 Beaching forces...............................................................25D 300 Ice compression loads amidships....................................25D 400 Local ice pressure ...........................................................25D 500 Accelerations...................................................................26

E. Global Strength .................................................................. 26E 100 General............................................................................26

E 200 Longitudinal strength......................................................26E 300 Transverse strength amidships........................................27E 400 Overall strength of substructure in the foreship..............28

F. Local Strength .................................................................... 28F 100 General............................................................................28F 200 Plating.............................................................................28F 300 Longitudinal stiffeners....................................................28F 400 Other stiffeners................................................................29F 500 Girders ............................................................................29

G. Rudders, Propeller Nozzles and Steering Gears ............. 30G 100 General............................................................................30G 200 Ice loads on rudders ........................................................30G 300 Rudder scantlings............................................................31G 400 Ice loads on propeller nozzles.........................................31

G 500 Propeller nozzle scantlings .............................................31G 600 Steering gear ...................................................................31

H. Welding ............................................................................... 31H 100 General............................................................................31H 200 External welding.............................................................31H 300 Fillet welds and penetration welds subject

to high stresses ................................................................31

I. Machinery Systems ............................................................ 32I 100 Pneumatic starting arrangement......................................32I 200 Sea inlets and discharges ................................................32I 300 Sea cooling water arrangements .....................................32I 400 Ballast system .................................................................32

J. Propulsion Machinery and Propellers ............................. 32J 100 General............................................................................32

J 200 Engine output..................................................................32J 300 Determination of ice torque............................................33J 400 Propeller..........................................................................33J 500 Shafting ...........................................................................33J 600 Thrust bearing .................................................................34J 700 Reduction gear ...............................................................34


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Rules for Ships, January 2005 Amended,Pt.5 Ch.1 Contents Page 4 see Pt.0 Ch.1 Sec.3, July 2005

DETNORSKEVERITAS

J 800 Flexible couplings and clutches ......................................34J 900 Fixed shaft couplings ......................................................35J 1000 Propeller fitting ...............................................................35J 1100 Spare parts.......................................................................35

K. Thrusters .............................................................................35K 100 General............................................................................35K 200 Shafting ...........................................................................35K 300 Reduction gear ................................................................35

K 400 Propeller..........................................................................35

L. Stability and Watertight Integrity ...................................35L 100 Application......................................................................35L 200 Documentation ................................................................35L 300 Requirements for intact stability.....................................35L 400 Requirements for damage stability .................................36L 500 Requirements to watertight integrity...............................36

SEC. 5 SEALERS ........................................................... 37

A. General ................................................................................37A 100 Classification...................................................................37

A 200 Hull form.........................................................................37

B. Strength of Hull and Superstructures...............................37B 100 Ship's sides and stem.......................................................37B 200 Superstructures................................................................37

C. Sternframe, Rudder and Steering Gear ...........................37C 100 Design rudder force.........................................................37C 200 Protection of rudder and propeller ..................................37

D. Anchoring and Mooring Equipment.................................37D 100 General............................................................................37

E. Machinery............................................................................37E 100 Output of propulsion machinery .....................................37E 200 Thrust bearing, reduction gear, shafting and

propeller ..........................................................................37E 300 Machinery systems..........................................................37


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Amended, Rules for Ships, January 2005see Pt.0 Ch.1 Sec.3, July 2005 Pt.5 Ch.1 Sec.1 Page 5

DETNORSKEVERITAS

SECTION 1GENERAL REQUIREMENTS

A. Classification

A 100 Application101 The rules in this chapter apply to vessels occasionally orprimarily intended for navigation in waters with ice conditions.The requirements shall be regarded as supplementary to thosegiven for the assignment of main class.

A 200 Class notations

201 Vessels complying with relevant additional require-ments of this chapter will be assigned one of the followingclass notations:

B. Definitions

B 100 Symbols

101 General

L = rule length in m *)B = rule breadth in m *)D = rule depth in m *)T = rule draught in m *) = rule displacement in t *)CB = block coefficient *)f = displacement in t in fresh water (density 1.0 t/m

3) at iceclass draught

Ps = maximum continuous output of propulsion machineryin kW

s = stiffener spacing in m measured along the plating be-tween ordinary and/or intermediate stiffenerss0 = spacing in m of ordinary main framesss = 0.48 + 0.002 L

(m) maximum 0.61 m forward of the collision bulk-head and abaft the afterpeak bulkhead

l = stiffener span in m measured along the top flange ofthe member. For definition of span point, see Pt.3 Ch.1Sec.3 C100

S = girder span in m. For definition of span point, see Pt.3Ch.1 Sec.3 C100.

F = minimum upper yield stress of material in N/mm2

NV-NS-steel may be taken as having F= 235 N/mm2

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

*) For details see Pt.3 Ch.1.

B 200 Terms

201 Load waterline,LWL:

The waterline corresponding to winter load line. For shipstrading in the Baltic during winter at summer load line, the icestrengthening shall be based on the summer load line, see alsoSec.3 A300.

202 Ballast waterline,BWL:

To be determined in such a way that the propeller, if possible,is completely submerged, see also Sec.3 A300.

C. Documentation

C 100 General

101 Details related to additional classes regarding design, ar-rangement and strength are in general to be included in theplans specified for the main class.

102 Additional documentation not covered by the main classare specified in appropriate sections of this chapter.

Table A1 Class notations

Notation Reference

ICE-C (See Sec.2)

ICE-1A*FICE-1A*ICE-1AICE-1BICE-1C

(See Sec.3)

ICE - 05(or - 10or - 15)POLAR - 10(or - 20or - 30)Icebreaker

(See Sec.4)

Sealer (See Sec.5)


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Rules for Ships, January 2005 Amended,Pt.5 Ch.1 Sec.2 Page 6 see Pt.0 Ch.1 Sec.3, July 2005

DETNORSKEVERITAS

SECTION 2BASIC ICE STRENGTHENING

A. General

A 100 Classification

101 The requirements in this section apply to passenger andcargo vessels intended for service in waters with light ice con-ditions.

102 Vessels built in compliance with the following require-ments may be given the class notation ICE-C.

103 In cases where the structural requirements of Sec.3(ICE-1C) give smaller scantlings than Sec.2, Sec.3 may be ap-plied.

104 Vessels with longitudinal framing shall have scantlingsfor plating and longitudinals as for class notation ICE-1C, us-ing 0.9 times the ice pressure as given in Sec.3. The extent ofice strengthening shall be as specified in B100 and B300.

B. Hull Arrangement and Scantlings

B 100 Shell plating

101 From stem to a distance B abaft F.P. and within a belt ex-tending vertically from 0.5 m above LWL to 0.5 m belowBWL, the shell plating thickness shall not be less than:

t = 6 + 0.11 L + t (mm), maximum 25 mm

t = 20 (so ss) (mm), minimum zero.

102 Abaft the area mentioned in 101, the shell plating thick-ness within the specified ice belt may be gradually reduced tonormal thickness at the position where the waterlines attaintheir full breadth.

B 200 Ordinary frames

201 Ordinary frames in fore peak shall have a section modu-lus not less than:

Z = 0.25 L T (cm3)

The distance between ordinary frames in fore peak shall notexceed 0.61 m.

202 From collision bulkhead to 1.5 B abaft F.P., the sectionmodulus of ordinary main frames shall not be less than:

Z = 0.4 L soT (cm3)

B 300 Intermediate ice frames

301 In the region from stem to 1.5 B abaft F.P., intermediateframes shall be fitted. The intermediate ice frames shall extendfrom 0.62 m above LWL to 1.0 m below BWL.

Bottom plating forward situated less than 0.5 m below BWLshall have intermediate stiffening between floors. Intermediateice frames may be omitted, if the spacing of the ordinaryframes is not exceeding:

0.37 m forward of collision bulkhead (0.288 + 0.0012 L), maximum 0.42 m abaft collision bulk-

head.

302 The intermediate ice frames shall have a section modu-lus not less than:

forward of collision bulkhead:

abaft collision bulkhead:

The required section modulus of intermediate frames forwardof the collision bulkhead is based on a frame span equal to 2 m.For different spans, the requirement is modified in direct pro-portion. Intermediate frames need in no case have a sectionmodulus larger than 75% of that of the ordinary frames.

303 The ends of intermediate ice frames shall be connected

to horizontal carlings between ordinary frames. These carlingsshall not form a continuous stringer. Where intermediate iceframes extend to a deck or inner bottom above or below the icebelt, it may have sniped ends. Acceptable types of intermediateframe connections are shown in Fig. 1.

Fig. 1Acceptable types of intermediate ice frame connections

B 400 Ice stringer

401 In single deck ships, an ice stringer shall be fitted 0.2 to0.3 m below LWL from stem to a distance 2 B abaft F.P.

Forward of the collision bulkhead, the ice stringer shall be agirder with scantlings as an ordinary girder on the ship's side.Abaft the collision bulkhead, the ice stringer shall consist of aseries of tripping brackets fitted to the frames.

B 500 Weld connections

501 Weld connections to shell in fore peak shall be doublecontinuous.

B 600 Sternframe and rudder

601 The section modulus of sternframe, rudder horn and solepiece shall be 7.5% greater than required for the main class.

602 Scantlings of rudders, rudder stocks and rudder shaftsshall be based on a rudder force 25% greater than a design val-ue calculated according to Pt.3 Ch.3 Sec.2 D101, with k1= k2= 1.0 irrespective of condition, rudder profile type and arrange-ment.

Z

L2

160--------- 10+

=

so

ss---- (cm

3

)

ZL

2

100--------- 20+

=

so

ss---- (cm

3)


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DETNORSKEVERITAS

C. Machinery

C 100 Output of propulsion machinery

101 The maximum continuous output is generally not to beless than:

Ps= 0.73 L B (kW)

For ships with a bow specially designed for navigation in ice,a reduced output may be accepted. In any case, the output shallnot be less than:

Ps= 0.59 L B (kW)

102 If the ship is fitted with a controllable pitch propeller, theoutput may be reduced by 10%.

103 For ships with steam turbines, the astern power shall notbe less than 70% of the forward power.

C 200 Design of propeller and propeller shaft

201 Relevant criteria in Sec.3 shall be applied, assuming theice torque in Nm:

TICE

= 35 200 R2for open propellers

TICE= 35 200 R2(0.9 0.0622 R-0.5) for ducted propellers

R = propeller radius (m).

202 The propeller shaft diameter need not exceed 1.05 timesthe rule diameter given for main class, irrespective of the di-mension derived from Sec.3.

C 300 Sea suctions and discharges

301 The sea cooling water inlet and discharge for main andauxiliary engines shall be so arranged so that blockage ofstrums and strainers by ice is prevented. In addition to require-ments in Pt.4 Ch.1 and Ch.6 the requirements in 302 and 303shall be complied with.

302 One of the sea cooling water inlet sea chests shall be sit-uated near the centre line of the ship and well aft. At least oneof the sea chests shall be sufficiently high to allow ice to accu-mulate above the pump suctions.

303 A full capacity discharge branched off from the coolingwater overboard discharge line shall be connected to at leastone of the sea inlet chests. At least one of the fire pumps shallbe connected to this sea chest or to another sea chest with de-icing arrangements.

Guidance note:

Heating coils may be installed in the upper part of the sea

chest(s). Arrangement using ballast water for cooling purposes isrecommended but will not be accepted as a substitute for sea inletchest arrangement as described above.

---e-n-d---of---G-u-i-d-a-n-c-e---n-o-t-e---


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DETNORSKEVERITAS

SECTION 3ICE STRENGTHENING FOR THE NORTHERN BALTIC

A. General

A 100 Classification

101 The requirements in this section apply to vessels forservice in the northern Baltic in winter or areas with similar iceconditions.

102 Vessels built in compliance with the following require-ments may be given one of the class notations ICE-1A*, ICE-1A, ICE-1Bor ICE-1Cwhichever is relevant.

Guidance note:

The ice class requirements are considered to meet the Finnish-Swedish Ice Class Rules 01 October 2002 for correspondingclasses.

Revision of these rules concern propulsion power and structuralstrength and applies to ships of which the keel is laid, or which isat a similar stage of construction on or after 1 September 2003.


103 Vessels built in compliance with the requirements rele-vant for class ICE-1A*and with the additional requirementsgiven below may acquire the class notation ICE-1A*F.

Guidance note:

The additional ice class ICE-1A*F is recommended applied tovessels with relatively high engine power designed for regulartraffic in the northern Baltic and other relevant areas, normallyoperating according to rather fixed timetables irrespective of iceconditions and to a certain degree independent of ice breaker as-sistance.


A 200 Assumptions

201 The method for determining the hull scantlings is basedon certain assumptions concerning the nature of the ice load onthe structure. These assumptions rest on full scale observations

made in the northern Baltic.

202 The formulae given for plating, stiffeners and girders arebased on special investigations as to the distribution of iceloads from plating to stiffeners and girders as well as redistri-bution of loads on stiffeners and girders. Special values havebeen given for distribution factors and certain assumptionshave been made regarding boundary conditions.

203 For the formulae and values given in this section for thedetermination of the hull scantlings more sophisticated meth-ods may be substituted subject to special approval.

204 If scantlings derived from these regulations are less thanthose required for an unstrengthened ship, the latter shall beused.

205 The frame spacing and spans defined in the followingtext are normally assumed to be measured in a vertical planeparallel to the centreline of the ship. However, if the ships sidedeviates more than 20from this plane, the frame distances andspans shall be measured along the side of the ship.

206 Assistance from icebreakers is normally assumed whennavigating in ice bound waters.

A 300 Definitions

301 Maximum draught amidships

The maximum ice class draught amidships shall be the draughton the Fresh Water Load Line in Summer. If the ship has a tim-ber load line, the Fresh Water Timber Load Line in Summershall be used.

302 Maximum and minimum draught fore and aft

The maximum and minimum ice class draughts fore and aftshall be determined and stated in the classification certificate.

The line defined by the maximum draughts fore, amidshipsand aft will henceforth be referred to as LWL. The line may bea broken line. The line defined by the minimum draughts foreand aft will be referred to as BWL.

The draught and trim, limited by the LWL, must not be exceed-ed when the ship is navigating in ice. The salinity of the seawater along the intended route shall be taken into accountwhen loading the ship. Filling of ballast tanks may be neces-sary to load the ship to the BWL. Any ballast tanks situated ful-ly or partly above the BWL adjacent to the ship's shell shall beequipped with anti-freezing device(s) to prevent the waterfrom freezing, see J603. In determining the BWL, regard shallbe paid to the need for ensuring a reasonable degree of ice go-ing capability in ballast. The propeller shall be fully sub-merged, if possible entirely below the ice. The minimumforward draught shall be at least:

(2 + 0.00025 f) ho (m)

but need not exceed 4 howhere

f = displacement of the ship (t) on the maximum ice classdraught according to 301

ho = ice thickness according to B101.

303 Ice belt regions

The ice belt is divided into regions as follows (see also Fig.1):

Forward region: From the stem to a line parallel to and 0.04 Laft of the forward borderline of the part of the hull where thewaterlines run parallel to the centre line. For ice classes ICE-

1A*F, ICE-1A* and ICE-1A the overlap of the borderlineneed not exceed 6 m, for ice classes ICE-1Band ICE-1Cthisoverlap need not exceed 5 m.

Midship region: From the aft boundary of the Forward regionto a line parallel to and 0.04 L aft of the aft borderline of thepart of the hull where the waterlines run parallel to the centreline. For ice classes ICE-1A*F, ICE-1A* and ICE-1A theoverlap of the borderline need not exceed 6 m, for ice classesICE-1Band ICE-1Cthis overlap need not exceed 5 m.

Aft region: From the aft boundary of the Midship region to thestern.

A 400 Documentation

401 LWL and BWL shall be indicated on the shell expansionplan together with the lines separating the forward, amidshipsand aft regions of the ice belt. The machinery, displacement,f, and the output of propulsion machinery, Ps, shall be statedon the shell expansion and/or the framing plan.

DNV Ice Class notation Equivalent Finnish-Swedish Ice

ClassICE-1A* 1A Super

ICE-1A 1A

ICE-1B 1B

ICE-1C 1C


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DETNORSKEVERITAS

Fig. 1Ice belt regions

B. Design Loads

B 100 Height of load area

101 An ice strengthened ship is assumed to operate in opensea conditions corresponding to a level ice thickness not ex-ceeding ho. The design height (h) of the area actually under icepressure at any particular point of time is, however, assumed to

be only a fraction of the ice thickness. The values for hoand hare given in the following table.

B 200 Ice pressure

201 The design ice pressure (based on a nominal ice pressureof 5 600 kN/m2) is determined by the formula:

p = 5 600 cd

c1

ca

(kN/m2)

cd = a factor which takes account of the influence of the sizeand engine output of the ship. It is calculated by theformula:

a and b are given in Table B2.

f = displacement (t) as defined in A302Ps = machinery output (kW) as defined in J101c1 = a factor which takes account of the probability that the

design ice pressure occurs in a certain region of thehull for the ice class in question.

The value of c1is given in Table B3:

For ice class ICE-1A*Fan additional lower forward ice belt(see C102) is defined with factor c1= 0.20.

ca = a factor which takes account of the probability that thefull length of the area under consideration will be un-der pressure at the same time. It is calculated by theformula:

lashall be taken as given in Table B4.

C. Shell PlatingC 100 Vertical extension of ice strengthening

101 The vertical extension of the ice belt (see Fig.1) shall notbe less than given in Table C1.

102 In addition the following areas shall be strengthened:

Fore foot: For ice class ICE-1A*and ICE-1A*Fthe shell plat-ing below the ice belt from the stem to a position five mainframe spaces abaft the point where the bow profile departsfrom the keel line shall have at least the thickness required inthe ice belt in the midship region, calculated for the actualframe spacing.

Upper forward ice belt: For ice classes ICE-1A*and ICE-1Aon ships with an open water service speed equal to or exceed-ing 18 knots, the shell plate from the upper limit of the ice beltto 2 m above it and from the stem to a position at least 0.2 Labaft the forward perpendicular, shall have at least the thick-ness required in the ice belt in the midship region, calculatedfor the actual frame spacing.

Guidance note:

A similar strengthening of the bow region is advisable also for aship with a lower service speed, when it is, e.g. on the basis of themodel tests, evident that the ship will have a high bow wave.


For ice class ICE-1A*Fthe upper forward ice belt shall be tak-

Table B1 Values of hoand h

Ice class ho(m) h (m)

ICE-1A*ICE-1AICE-1BICE-1C

1.00.80.60.4

0.350.300.250.22

Table B2 Values of a and b

RegionForward Midship and aft

k 12 k > 12 k 12 k > 12

a 30 6 8 2

b 230 518 214 286

cda +

1000---------------=

kfPs

1000---------------=

Table B3 Values of c1

Ice classRegion

Forward Midship Aft

ICE-1A* 1.0 1.0 0.75

ICE-1A 1.0 0.85 0.65

ICE-1B 1.0 0.70 0.45

ICE-1C 1.0 0.50 0.25

Table B4 Values of laStructure Type of framing la

Shelltransverse frame spacing

longitudinal 2 x frame spacing

Framestransverse frame spacing

longitudinal span of frame

Ice stringer span of stringer

Web frame 2 x web frame spacing

Table C1 Vertical extension of ice belt

Ice class Above LWL (m) Below BWL (m)

ICE 1A*ICE 1AICE 1BICE 1C

0.60.50.40.4

0.750.60.50.5

ca

47 5la

44------------------- , maximum 1.0, minimum 0.6=


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DETNORSKEVERITAS

en 3 m above the normal ice belt, extending within the forwardregion.

Lower forward ice belt: For ice class ICE-1A*Fa lower for-ward ice belt below the normal ice belt is defined covering theforward region aft of the forefoot and down to the lower turnof bilge.

103 Sidescuttles shall not be situated in the ice belt. If the

weather deck in any part of the ship is situated below the upperlimit of the ice belt (e.g. in way of the well of a raised quarterdeck), the bulwark shall be given at least the same strength asis required for the shell in the ice belt. The strength of the con-struction of the freeing ports shall meet the same requirements.

C 200 Plate thickness in the ice belt

201 For transverse framing the thickness of the shell platingshall be determined by the formula:

For longitudinal framing the thickness of the shell plating shallbe determined by the formula:

p PL= 0.75 pp = as given in B200.

x1 =

x2 =

= 1.4 0.4 (h/s); when 1 h/s < 1.8

= 0.35 + 0.183 (h/s) for 1.8 h/s < 3 = 0.9 for h/s > 3

h = as given in B100

F = yield stress of the material (N/mm2)

tc = increment for abrasion and corrosion (mm); normally2 mm. If a special surface coating, by experienceshown capable to withstand the abrasion of ice, is ap-plied and maintained, lower values may be approved.

202 For ice class ICE-1A*F the following additional re-quirements are given:

bottom plating in the forward region (below the lower for-ward ice belt defined in 102) shall have a thickness not less

than:

side and bottom plating in the aft region below the ice beltshall have a thickness not less than:

D. Frames

D 100 Vertical extension of ice framing

101 The vertical extension of the ice strengthening of theframing shall be at least as given in Table D1:

Where an upper forward ice belt is required (see C102), the icestrengthened part of the framing shall be extended at least tothe top of this ice belt.

102 Where the ice strengthening would go beyond a deck ora tank top by not more than 250 mm, it can be terminated atthat deck or tank top.

D 200 Transverse frames

201 The section modulus of a main or intermediate trans-verse frame shall be calculated by the formula:

p = ice pressure as given in B200h = height of load area as given in B100

mt =

mo = values as given in Table D2.

t 21.1sx1 p PL

F------------------ tc (mm)+=

t 21.1sp PL

x2F------------ tc (mm)+=

1.34.2

h s 1.8+( )2

--------------------------------- , maximum 1.0

0.60. 4

h s( )----------------, when h/s 1+

t 0.7 s 0.8+( )235L

F------------- (mm), minimum 12 mm=

Table D1 Vertical extension of ice strengthening of the

framing

Ice class Region Above LWL(m)

Below BWL(m)

ICE-1A*F

forward 1.2to double bot-tom or belowtop of floors

midship 1.2 1.6

aft 1.2 1.2

ICE-1A*

from stem to0.3 L abaft it

1.2to double bot-tom or belowtop of floors

abaft 0.3 L fromstem

1.2 1.6

midship 1.2 1.6

aft 1.2 1.2

ICE-1A,1B, 1C

from stem to0.3 L abaft it

1.0 1.6

abaft 0.3 L fromstem

1.0 1.3

midship 1.0 1.3

aft 1.0 1.0

t 0.6 s 0.8+( )235L

F------------- (mm), minimum 10 mm=

Zp s h l

mtF---------------10

3 cm

3( )=

7mo

7 5h l------------------------


11/37


DETNORSKEVERITAS

The boundary conditions are those for the main and intermedi-ate frames. Possible different conditions for main and interme-diate frames are assumed to be taken care of by interactionbetween the frames and may be calculated as mean values.Load is applied at mid span.

If the ice belt covers less than half the span of a transverseframe, (b < 0.5 l) the following modified formula may be usedfor the section modulus:

b = distance in m between upper or lower boundary of theice belt and the nearest deck or stringer within the icebelt.

Where less than 15% of the span, l, of the frame is situatedwithin the ice-strengthening zone for frames as defined inD101, ordinary frame scantlings may be used.

202 Upper end of transverse framing

1) The upper end of the strengthened part of a main frame and

of an intermediate ice frame shall be attached to a deck oran ice stringer (see E).

2) Where an intermediate frame terminates above a deck oran ice stringer which is situated at or above the upper limitof the ice belt (see C100) the part above the deck or string-

er may have the scantlings required for an unstrengthenedship and the upper end be connected to the adjacent mainframes by a horizontal member of the same scantlings asthe main frame. Such an intermediate frame can also beextended to the deck above and if this is situated more than1.8 metre above the ice belt the intermediate frame neednot be attached to that deck, except in the Forward region.

203 Lower end of transverse framing

1) The lower end of the strengthened part of a main frame andof an intermediate ice frame shall be attached to a deck,tank top or ice stringer (see E).

2) Where an intermediate frame terminates below a deck,tank top or ice stringer which is situated at or below thelower limit of the ice belt (see C100), the lower end to beconnected to the adjacent main frames by a horizontalmember of the same scantlings as the frames.

D 300 Longitudinal frames

301 The section modulus of a longitudinal frame shall be cal-culated by the formula:

The shear area of a longitudinal frame shall be:

These formulae assume that the longitudinal frame is attachedto supporting structure as required in 401.

x3 = factor which takes account of the load distribution toadjacent frames:

x3= (1 0.2 h/s)

x4 = factor which takes account of the concentration of loadto the point of support:

x4= 0.6

p = ice pressure as given in B200h = height of load area as given in B100m1 = boundary condition factor; m1= 12 shall be used for

continuous longitudinals. Where the boundary condi-tions deviate significantly from a continuous beam, asmaller factor may be required.

D 400 Structural details

401 Within the ice strengthened area all frames shall be ef-fectively attached to all supporting structures. Longitudinal ortransverse frames crossing supporting structures, such as webframes or stringers, shall be connected to these structures onboth sides (by collar plates or lugs in way of cut-outs).

Brackets or top stiffeners shall be fitted, in order to provideproper transfer of forces to supporting elements, as necessary.Connection of non-continuous frames to supporting structuresshall be made by brackets or similar construction. When abracket is installed, it has to have at least the same thickness asthe web plate of the frame, and the edge shall be appropriately

stiffened against buckling.402 For ice class ICE-1A*Fand ICE-1A*, for ice class ICE-1Ain the forward and midship regions and for ice classes ICE-1Band ICE-1Cin the forward region, the following shall ap-ply in the ice strengthened area:

Table D2 Values of mo

Boundary condi-tion

mo Example

7Frames in a bulk carrier with top wing

tanks

6Frames extending from the tank top to a

single deck

5.7Continuous frames between several

decks or stringers

5Frames extending between two decks

only

Z p s h b l b( )2

F l2

---------------------------------- 103 cm3( )=

Zx3 x4 p h l

2

m1F-------------------------- 10

3 cm

3( )=

A8.7x3p h l

F------------------------- cm

2( )=


12/37


DETNORSKEVERITAS

1) Frames which are not at a straight angle to the shell shallbe supported against tripping by brackets, intercostals,stringers or similar at a distance preferably not exceeding1.3 m.

Transverse frames perpendicular to shell which are of un-symmetrical profiles shall have tripping preventions if thespan is exceeding 4.0 m.

2) Frames and girder webs shall be attached to the shell bydouble continuous welds. No scalloping is allowed (ex-cept when crossing shell plate butts).

3) The web thickness of the frames shall be at least one halfof the thickness of the shell plating and at least 9 mm.

Where there is a deck, tank top or bulkhead in lieu of aframe the plate thickness of this shall be as above, to adepth corresponding to the height of adjacent frames.

E. Ice Stringers

E 100 Stringers within the ice belt

101 The section modulus of a stringer situated within the icebelt (see C100) shall be calculated by the formula:

The shear area shall not be less than:


The product p h shall not be taken as less than 300l = span of stringer (m)

m1 = boundary condition factor as given in D301.

E 200 Stringers outside the ice belt

201 The section modulus of a stringer situated outside the icebelt but supporting ice strengthened frames shall be calculatedby the formula:

The shear area shall not be less than:


The product p h shall not be taken as less than 300.

l = span of stringer (m)m1 = boundary condition factor as given in D301ls = the distance to the adjacent ice stringer(m)hs = the distance to the ice belt (m).

E 300 Deck strips

301 Narrow deck strips abreast of hatches and serving as icestringers shall comply with the section modulus and shear arearequirements in 100 and 200 respectively. In the case of very

long hatches the lower limit of the product p h may be reducedto 200.

302 Regard shall be paid to the deflection of the ship's sidesdue to ice pressure in way of very long hatch openings, whendesigning weatherdeck hatch covers and their fittings.

F. Web Frames

F 100 Design load

101 The load transferred to a web frame from an ice stringeror from longitudinal framing shall be calculated by the formu-la:

F = p h s (kN)

p = ice pressure as given in B200, when calculating factorca, however, lashall be taken as 2 s

h = height in m of load area as given in B100

The product ph shall not be taken less than 300.

s = web frame spacing in m

In case the supported stringer is outside the ice belt, the load Fmay be multiplied by:

as given in E201.

Fig. 2Web frame

F 200 Section modulus and shear area

201 For a web frame simply supported at the upper end andfixed at the lower end (see Fig.2), the section modulus require-ment is given by:

M = maximum calculated bending moment under the loadF, as given in 101

= as given in Table F1A = required shear area from 202Aa = actual cross sectional area of web plate.

202 With boundary conditions as given in 201, the shear areaof a web frame is given by:

Q = maximum calculated shear force under the load F, asgiven in 101 = factor given in Table F1Af = cross sectional area of free flangeAw = cross sectional area of web plate.

Z0 .9ph l

2

m1F---------------------10

3 cm

3( )=

A7 . 8 p h l

F------------------- cm

2( )=

Z0.95ph l

2

m1F------------------------ 1

hs

ls-----

10

3 cm

3( )=

A8.2 p h l

F------------------- 1

hs

ls-----

cm

2( )=

1s

ls-----

ZM

F------ 1

1 A

Aa------

2

--------------------------103 (cm

3)=

A17.3 Q

F-------------------- (cm

2)=


13/37


DETNORSKEVERITAS

203 For other web frame configurations and boundary con-ditions than given in 201, a direct stress calculation should beperformed.

The concentrated load on the web frame is given in 101.

The point of application is in each case to be chosen in relationto the arrangement of stringers and longitudinal frames so as toobtain the maximum shear and bending moments.

Allowable stresses are as follows:

shear stress:

bending stress:

equivalent stress:

G. Bilge Keels

G 100 Arrangement

101 The connection of bilge keels to the hull shall be so de-signed that the risk of damage to the hull, in case a bilge keelis ripped off, is minimised.

102 To limit damage when a bilge keel is partly ripped off, itis recommended that bilge keels are cut up into several shorterindependent lengths.

103 For class ICE-1A*F bilge keels are normally to beavoided and should be replaced by roll-damping equipment.Specially strengthened bilge keels may be considered.

H. Special Arrangement and Strengthening For-ward

H 100 Stem, baltic ice strengthening

101 The stem may be made of rolled, cast or forged steel orof shaped steel plates. A sharp edged stem (see Fig.3) improvesthe manoeuvrability of the ship in ice and is recommended par-ticularly for smaller ships with length less than 150 m.

Fig. 3Welded stem

102 The plate thickness of a shaped plate stem and in the

case of a blunt bow, any part of the shell which forms an angleof 30 or more to the centre line in a horizontal plane, shall becalculated according to the formulae in C200 assuming that:

s = spacing of elements supporting the plate (m)pPL = p (see B200).

la = spacing of vertical supporting elements (m).

For class ICE-1A*Fthe front plate and upper part of the bulband the stem plate up to a point 3.6 m above LWL (lower partof bow door included) shall have a minimum thickness of:

c = 2.3 for the stem plate

= 1.8 for the bulb plating.

The width of the increased bulb plate shall not be less than 0.2b on each side of the centre line, b being the breadth of the bulbat F.P.

103 The stem and the part of a blunt bow defined above shallbe supported by floors or brackets spaced not more than 0.6 mapart and having a thickness of at least half the plate thickness.The reinforcement of the stem shall be extend from the keel toa point 0.75 m above LWL or, in case an upper forward ice beltis required (C102) to the upper limit of this.

H 200 Arrangements for towing

201 A mooring pipe with an opening not less than 250 by

300 mm, a length of at least 150 mm and an inner surface radi-us of at least 100 mm shall be fitted in the bow bulwark at thecentre line.

202 A bitt or other means for securing a towline, dimen-sioned to stand the breaking force of the towline of the shipshall be fitted.

203 On ships with a displacement not exceeding 30 000 tonsthe part of the bow which extends to a height of at least 5 mabove the LWL and at least 3 m aft of the stem, shall bestrengthened to take the stresses caused by fork towing. Forthis purpose intermediate frames shall be fitted and the framingshall be supported by stringers or decks.

204 It shall be noted that for ships of moderate size (displace-

ment not exceeding 30 000 tons) fork towing in many situa-tions is the most efficient way of assisting in ice. Ships with abulb protruding more than 2.5 m forward of the forward per-pendicular are often difficult to tow in this way. The adminis-trations reserve the right to deny assistance to such ships if thesituation so warrants.

F 3=

b F=

c b2

32

+ F= =

Table F1 Values of and

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

1.5 1.23 1.16 1.11 1.09 1.07 1.06 1.05 1.05 1.04 1.04

0 0.44 0.62 0.71 0.76 0.80 0.83 0.85 0.87 0.88 0.89

Af

Aw--------

t c235L

f------------- (mm)=


14/37


DETNORSKEVERITAS

I. Special Arrangement and Strengthening Aft

I 100 Stern

101 The introduction of new propulsion arrangements withazimuthing thrusters or podded propellers, which provide animproved manoeuvrability, will result in increased ice loadingof the aft region and stern area. This fact should be considered

in the design of the aft/stern structure.102 An extremely narrow clearance between the propellerblade tip and the stern frame shall be avoided as a small clear-ance would cause very high loads on the blade tip.

103 On twin and triple screw ships the ice strengthening ofthe shell and framing shall be extended to the double bottomfor 1.5 metre forward and aft of the side propellers.

104 Shafting and stern tubes of side propellers are normallyto be enclosed within plated bossings. If detached struts areused, their design, strength and attachment to the hull shall beduly considered.

For class ICE-1A*Fthe skin plating of propeller shaft bossingsshall not be less than:

105 A wide transom stern extending below the LWL will se-riously impede the capability of the ship to run astern in ice,which is most essential. Therefore a transom stern shall not beextended below the LWL if this can be avoided. If unavoida-ble, the part of the transom below the LWL shall be kept as nar-row as possible. The part of a transom stern situated within theice belt shall be strengthened as for the midship region.

I 200 Rudder and steering arrangements

201 The scantlings of rudder, rudder post, rudder stock, pin-tles, steering gear etc. as well as the capacity of the steeringgear shall be determined according to the rules. The maximumservice speed of the ship to be used in these calculations is,however, not to be taken less than that stated below:

If the actual maximum service speed of the ship is higher, that

speed shall be used.When calculating the rudder force according to the formulagiven in Pt.3 Ch.3 Sec.2 D and with the speed V in ahead con-dition as given above, the factors k1= k2= 1.0 irrespective ofcondition, rudder profile type or arrangement. In the asterncondition half the speed values shall be used.

202 For the ice classes ICE-1A* and ICE-1A the rudderstock and the upper edge of the rudder shall be protectedagainst ice pressure by an ice knife or equivalent means.

Guidance note:

Upper forward part of rudder and forward part of rudder hornshould be protected against abrasion by a special coating or in-crease in thickness.


203 For ice classes ICE-1A*and ICE-1Adue regard shall bepaid to the excessive loads caused by the rudder being forcedout of the midship position when backing into an ice ridge.

204 Relief valves for hydraulic pressure shall be effective.The components of the steering gear shall be dimensioned tostand the yield torque of the rudder stock. Where possible rud-der stoppers working on the blade or rudder head shall be fit-ted.

205 Parts of rudder within the ice belt shall have local thick-ness at least equivalent to the side shell in the afterbody.

J. Machinery

J 100 Engine output

101 Definition of engine output

The engine output PSis the maximum output the propulsionmachinery can continuously deliver to the propeller(s). If theoutput of the machinery is restricted by technical means or byany regulations applicable to the ship, PSshall be taken as therestricted output.

102 Documentation on board

Minimum engine output corresponding to the ice class shall begiven in the Classification Certificate.

103 Required engine output for ice classes

Definitions

The dimensions of the ship and some other parameters are de-fined below:

L = length of the ship between the perpendiculars (m)LBOW = length of the bow (m), Fig.4L PAR = length of the parallel midship body (m), Fig.4B = maximum breadth of the ship (m)T = actual ice class draughts of the ship (m) according to

A301

A wf = area of the waterline of the bow (m2), Fig.4 = the angle of the waterline at B/4 (), Fig.41 = the rake of the stem at the centreline (), Fig.42 = the rake of the bow at B/4 (), Fig.4DP = diameter of the propeller or outer diameter of nozzle

for the nozzle propeller, maximum 1.2 times propel-ler diameter (m)

HM = thickness of the brash ice in mid channel (m)HF = thickness of the brash ice layer displaced by the bow

(m).

Range of validity

The range of validity of the formulae for powering require-ments in 104 is presented in Table J1. When calculating the pa-

rameter DP/T, T shall be measured at LWL.

If the ships parameter values are beyond the ranges defined inTable J1, other methods for determining RCHshall be used asdefined in 105.

Table I1 Maximum service speed

Ice class Maximum service speed

ICE-1A*ICE-1AICE-1BICE-1C

20 knots18 knots16 knots14 knots

t 0.9 s 0.8+( )235L

f------------- (mm).=

Table J 1 Parameter validity range

Parameter Minimum Maximum

[degrees] 15 55

1[degrees] 25 90

2[degrees] 10 90

L [m] 65.0 250.0

B [m] 11.0 40.0

T [m] 4.0 15.0

LBOW/L 0.15 0.40

LPAR/L 0.25 0.75

DP/T 0.45 0.75

Awf/(L*B) 0.09 0.27


15/37


DETNORSKEVERITAS

Fig. 4Definitions

104 The engine output requirement shall be calculated forfollowing two draughts:

the maximum draught amidship referred to as LWL and the minimum draught referred to as BWL, as defined in

A302.

In the calculations the ship's parameters which depend on thedraught shall be determined at the appropriate draught, but Land B shall be determined only at the LWL. The engine output

shall not be less than the greater of these two outputs.The engine output PSshall not be less than that determined bythe formulae and in no case less than given in Table J3:

Guidance note:

New ships see A102 Guidance note.

For existing ICE-1Aand ICE-1A*ships see Pt.7 Ch.1 Sec.6 F.


RCHis the resistance in Newton of the ship in a channel withbrash ice and a consolidated layer:

C = 0.15 cos2 + sin sin 0.45C = 0.047 2.115 and 0 if 45

HF = 0.26 + (HMB)0.5

HM = 1.0 for ICE-1Aand ICE-1A*= 0.8 for ICE-1B= 0.6 for ICE-1C

C1and C2take into account a consolidated upper layer of thebrash ice and can be taken as zero for ice class ICE-1A, ICE-1Band ICE-1C.

For ice class ICE-1A*:

For a ship with a bulbous bow, 1shall be taken as 90.

f1 = 23 (N/m2)

f2 = 45.8 (N/m)f3 = 14.7 (N/m)f4 = 29 (N/m

2)g1 = 1 530 (N)g2 = 170 (N/m)g3 = 400 (N/m

1.5)C3 = 845 (kg/(m

2s2))C4 = 42 (kg/(m

2s2))C5 = 825 (kg/s

2)

Table J2 Value of factor Ke

Propeller type or machinery

Numbers ofpropellers

Controllable pitch propeller orelectric or hydraulic propulsion

machinery

Fixed pitchpropeller

1 propeller 2.03 2.26

2 propellers 1.44 1.6

3 propellers 1.18 1.31

Table J3 Minimum engine output PS

ICE-1A, ICE-Band ICE-C 1 000 kW

ICE-1A* 2 800 kW

PS Ke

RCH

1000------------

DP-----------------

3

2---

(kW)=

RCH

C1

C2

C3

C

HF

HM

+( )2

B C

HF

+( )

C4

LPA R

HF2

C5LT

B2

------- 3

Awf

L---------- (N)+

+ + +=

C1

f1

BLPA R

2T

B---- 1+

-------------------- 1 0.0211+( ) f2B f3LBO W f4BLBO W+ +( )+=

C

2

1 0.0631

+( ) g

1

g

2

B+( ) g

3

1 1.2T

B

----+ B

2

L

-------+=

arctan

2tan

sin-------------- =

The following shall apply: 20LT

B2

------- 3 5


16/37


DETNORSKEVERITAS

105 Other methods of determining Keor RCH

For an individual ship, in lieu of the Keor RCHvalues definedin Table J2 and 104, the use of Keor RCHvalues based on moreexact calculations or values based on model tests may be ap-proved. Such approval will be given on the understanding thatit can be revoked if experience of the ships performance inpractice motivates this.

The design requirement for ice classes shall be a minimumspeed of 5 knots in the following brash ice channels (see TableJ4):

J 200 Design loads for propeller and shafting

201 The formulae for scantlings are based on the followingloads:

To = mean torque of propulsion engine at maximum con-tinuous rating in Nm

(If multi-engine plant, Tois the mean torque in anactual branch or after a common point. Tois alwaysreferred to engine r.p.m.)

Tho = mean propeller thrust in N at maximum continuousspeed

R = as given in 301.Tice = ice torque in Nm (referred to propeller r.p.m.) and

found from Table J5.

J 300 Propeller

301 The particulars governing the requirements for scant-lings are:

R = propeller radius (m)Hr = pitch in m at radius in question = rake in degrees at blade tip (backward rake positive)Z = number of bladest = blade thickness in mm at cylindrical section consid-

eredt0.25= t at 0.25 Rt0.35= t at 0.35 Rt0.6 = t at 0.6 Rcr = blade width in m at cylindrical section consideredc0.25= crat 0.25 Rc0.35= crat 0.35 Rc0.6 = crat 0.6 Ru = gear ratio:

If the shafting system is directly coupled to engine, u = 1.

no = propeller speed at maximum continuous output, forwhich the machinery shall be approved, in revolutionsper minute.

302 Propellers shall be of steel or bronze as specified for pro-peller castings in Pt.2 Ch.2.

303 Moderately or highly skewed propellers will be espe-cially considered with respect to scantlings.

304 The blade thickness of the cylindrical sections at 0.25 R(fixed pitch propellers only) and at 0.35 R shall not be lessthan:

The thickness at 0.6 R shall not be less than:

U1and U2 = material constants to be taken as given in Pt.4Ch.5 Sec.1 Table B1.

For fixed blade propellers

For controllable pitch propellers

K4 = kiZ Ticesin

C1,C2,C3,C4= as given in Table J6.

A = q0+ q1d + q2d2+ q3d

3

q0,q1,q2,q3= as given in Table J7.

d =

d =

ki = 96 at 0.25 R

= 92 at 0.35 RKMat = 1.0 for stainless steel propellers = 0.8 for other materials

sin =

=

K1as given above is only valid for propulsion by diesel en-gines (by about zero speed, it is assumed 85% thrust and 75%

torque for fixed blade propellers and 125% thrust and 100%torque for controllable pitch propellers).

For turbine, diesel-electric or similar propulsion machinery K1will be considered in each particular case.

The thickness of other sections is governed by a smooth curve

Table J4 Values of HM

Ice class HMICE-1A* 1.0 m and a 0.1 m thick consolidated layer of ice

ICE-1A 1.0 m

ICE-1B 0.8 m

ICE-1C 0.6 m

Table J5 Values of Tice

Ice class Open propeller Ducted propeller

ICE-1A* 84 000 R2 62 400 R2

ICE-1A 62 400 R2 52 000 R2

ICE-1B 52 000 R2 47 600 R2

ICE-1C 47 600 R242 800 R2.R > 3 m

40 400 R2. R < 1.5 m 1)

1) For 1.5 m < R < 3 m, Tice may be found by linear interpolation.

uengine r .p .m.

propeller r .p .m.--------------------------------------------=

t C12RK1 U2C4 0.2+( ) K4+

Zc r K( Ma t U1 U2Sr )------------------------------------------------------------- (mm)=

t t0.35

0.45c0.35

c0.6----------------------- (mm)=

Sr

=2Rno

100

-------------

2

C2

C3

+( )

K1 = A1d T ho0.85 A2+

0.75uTo

R---------------------

K1 = A1d T ho1.25 A2

uTo

R---------+

2R

Hr----------- for fixed blade propellers

2R

0.7Hr-------------- for controllable pitch propellers

4

d2

16+

---------------------- at 0.25 R

2.86

d2

8.18+

--------------------------- at 0.35 R


17/37


DETNORSKEVERITAS

connecting the above section thicknesses.

305 The blade tip thickness at the radius 0.95 R shall not beless than given by the following formulae:

For ICE-1A*:

For ICE-1A, ICE-1Bor ICE-1C

b = ultimate tensile strength in N/mm2of propeller blade

material.

The thickness of the blade edge and the propeller tip shall notbe less than 50% of minimum t as given above, measured at1.25 t from the edge or tip, respectively. For controllable pitchpropellers where the direction of rotation is not reversible, thisrequirement only applies to the leading edge and propeller tip.

306 If found necessary by the torsional vibration calcula-tions, minor deviations from the dimensions given in 304 and305 may be approved upon special consideration.

307 The section modulus of the blade bolt connection re-ferred to an axis tangentially to the bolt pitch diameter, shallnot be less than:

b = tensile strength of propeller blade material (N/mm2)y = yield stress of bolt material (N/mm

2)

The propeller blade foot shall have a strength (including stressconcentration) not less than that of the bolts.

308 If a key is used for fitting of the propeller, the dimen-sions of the key shall be sufficient to transmit the full torqueincluding the ice torque, without exceeding the yield stressesin the materials.

309 If the propeller is bolted to the propeller shaft, the boltconnection shall have at least the same bending strength as thepropeller shaft.

The strength of the propeller shaft flange (including stress con-

centration) shall be at least the same as the strength of the bolts.

J 400 Shafting

401 The diameter of the propeller shaft at the aft bearingshall not be less than:

b = tensile strength of propeller blade material (N/mm2)

y = yield strength of propeller shaft material (N/mm2)

c0.35= as defined in 301

t0.35= as defined in 301.

Between the aft and second aft bearing, the shaft may be even-ly tapered to 1.22 times the diameter of the intermediate shaft,as required for the main class.

Forward of the after peak bulkhead, the shaft may be evenly ta-pered down to 1.05 times the rule diameter of intermediateshaft, but not less than the actual diameter of the intermediateshaft.

402 The diameter of the intermediate shaft, as required forthe main class, shall be multiplied by the factor:

u = as defined in 301I = equivalent mass moment of inertia in kgm2based on

torque of all parts on engine side of component underconsideration.

Masses rotating with engine speed to be transformedaccording to:

Iequiv= I actualu2

In propulsion systems with hydraulic or electromag-netic slip coupling, the masses in front of the couplingshall not be taken into consideration

It = equivalent mass moment of inertia of propulsion sys-

tem in kgm2. (Masses in front of hydraulic or electro-magnetic slip coupling shall not be taken intoconsideration.)

Note that Kmwill have different values forward and aft of aflywheel or reduction gear.

J 500 Thrust bearing, reduction gear, couplings andcrankshafts

501 The thrust bearing shall be dimensioned for a thrust ac-cording to:

502Reduction gears shall satisfy the requirements given inPt.4 Ch.4 Sec.2 when KAin the formulae for Hand Fis sub-

stituted by:

K1 = 1.0 for diesel engine driven plantsK1 = Tmax/ T0for electric motor driven plantsu = as defined in 301.I and It= as defined in 402.

Guidance note:

Normally, no reinforcement of crankshafts is considered neces-sary. In certain cases, especially with smaller engines (up to1 500 kW) with built-up crankshafts and flywheel at the forward

end, the sum of the maximum dynamic torque of the engine andthe impact torque

Table J6 Values of C1, C2, C3, C4

r 0.25 R 0.35 R 0.6 R

C1 0.278 0.258 0.150

C2 0.026 0.025 0.020

C3 0.055 0.049 0.034

C4 1.38 1.48 1.69

Table J7 Values of q0, q1, q2, q3

R q0 q1 q2 q3

0.25 RA1A2

8.3063.80

0.370-4.500

-0.340-0.640

0.0300.0845

0.35 RA1A2

9.5557.30

-0.015-7.470

-0.339-0.069

0.03220.0472

0.6 RA1A2

14.6052.90

-1.720-10.300

-0.1030.667

0.02030.0

t 20 4R+( ) 490b---------- (mm)=

t 15 4R+( )490

b---------- (mm)=

Wb 0.1 c0.35 t0.352 b

y------ cm

3( )=

dp 11.5bC0.35t0.35

2

y-------------------------------

1

3---

(mm)=

KM

1.25Tic eI

uToIt------------------------

1

3---

, minimum 1.0=

Th 1.3Tho

Tic e

R---------- (N)+=

KAice

Tic eI

UT0It-------------- K1+=

Tic eI

u It------------


18/37


DETNORSKEVERITAS

should not exceed 85% of friction torque of the shrink.


503 Clutches shall be designed according to Pt.4 Ch.4 Sec.3B.

504 Elastic couplings shall be designed according to Pt.4Ch.4 Sec.5 B.

J 600 Miscellaneous machinery requirements

601 Starting arrangements

The capacity of the air receivers shall be according to the re-quirements in Pt.4 Ch.6 Sec.5 I.

If the air receivers serve any other purposes than starting thepropulsion engine, they shall have additional capacity suffi-cient for these purposes.

The capacity of the air compressors shall be sufficient forcharging the air receivers from atmospheric to full pressure inone (1) hour, except for a ship with the ice class ICE-1A*if itspropulsion engine has to be reversed for going astern, in whichcase the compressors shall be able to charge the receivers inhalf an hour.

602 Sea inlet and cooling water systems.

The cooling water system shall be designed to ensure supply ofcooling water when navigating in ice. The sea cooling waterinlet and discharge for main and auxiliary engines shall be soarranged that blockage of strums and strainers is prevented.

For this purpose at least one cooling water inlet chest shall bearranged as follows:

1) The sea inlet shall be situated near the centre line of theship and well aft if possible. The inlet grids shall be spe-cially strengthened.

2) As a guidance for design the volume of the chest shall beabout one cubic metre for every 750 kW engine output of

the ship including the output of the auxiliary engines nec-essary for the ship's service.

3) To allow for ice accumulation above the pump suction theheight of the sea chest shall not be less than:

Vs= volume of sea chest according to item 2.

The suction pipe inlet shall be located not higher thanhmin/3 from top of sea chest.

4) A pipe for discharge cooling water, allowing full capacitydischarge, shall be connected to the chest. Where the seachest volume and height specified in 2 and 3 are not com-plied with, the discharge shall be connected to both seachests. At least one of the fire pumps shall be connected to

this sea chest or to another sea chest with de-icing arrange-ments.

5) The area of the strum holes shall be not less than four (4)times the inlet pipe sectional area.

If there are difficulties in meeting the requirements of 2) and 3)above, two smaller chests may be arranged for alternating in-take and discharge of cooling water. The arrangement and sit-uation otherwise shall be as above.

Heating coils may be installed in the upper part of the chest orchests.

Arrangements using ballast water for cooling purposes may beuseful as a reserve in ballast condition but can not be acceptedas a substitute for sea inlet chests as described above.

603 Ballast system

An arrangement to prevent freezing of the ballast water shallbe provided for in ballast tanks located fully or partly above theBWL, adjacent to the ship's shell, and needed to be filled foroperation in ice conditions according to A302. For this purposethe following ambient temperatures shall be taken as designconditions:

Sea water temperature: 0C Air temperature: 10C

Necessary calculations shall be submitted.

When a tank is situated partly above the BWL, an air-bubblingarrangement or a vertical heating coil, capable of maintaining

an open hole in the ice layer, will normally be accepted.

The required heat-balance calculations may then be omitted.

Guidance note:

It is assumed that, before pumping of ballast water is com-menced, proper functioning of level gauging arrangements isverified and air pipes are checked for possible blockage by ice.


hmi n 1.5 Vs3


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DETNORSKEVERITAS

SECTION 4VESSELS FOR ARCTIC AND ICE BREAKING SERVICE

A. General

A 100 Classification101 The requirements in this section apply to icebreakersand to passenger and cargo vessels intended to operate unas-sisted in ice-infested waters of sub-Arctic, Arctic and/or Ant-arctic regions.

102 Vessels intended for ice breaking as their main purposeand built in compliance with the following requirements maybe given one of the class notations Icebreaker ICE-05(or -10or -15) or Icebreaker POLAR-10(or -20or -30), which-ever is relevant.

Vessels built for another main purpose, while also intended forice breaking, may be given the additional class notation ICE-05(or -10or -15) or the notation POLAR-10(or -20or -30).

103 Arctic class vessels intended for special services whereintermediate ice condition values are relevant may, upon spe-cial consideration, be given intermediate notations (e.g. PO-LAR-25).

104 For POLARclass vessels the design ambient air tem-perature on which the classification has been based will be giv-en the special feature notation DAT(xC). The highesttemperatures to be applied for year round operations are statedin B100. For Arctic and/or Antarctic operations with area andseasonal restrictions higher design ambient air temperaturesmay be accepted as basis for the classification.

105 For vessels with the class notation Icebreaker, and forother POLARclass vessels the maximum operational speedon which the ramming design requirements have been basedwill be stated in the Appendix to the classification certifi-cate. The operational speed is in no case to be taken as smallerthan stated in 300 for the various class notations.

A 200 Scope

201 The following matters are covered by the classification:

materials in structures exposed to low ambient air temper-atures

subdivision, intact and damage stability hull girder longitudinal and transverse strength local hull structures exposed to ice loads rudders and steering gears propellers and propulsion machinery sea suctions for cooling water air starting systems

Fig. 1Commonly used definitions of temperatures

MDHT Mean daily high (or maximum) temperatureMDAT Mean daily average temperatureMDLT Mean daily low (or minimum) temperatureMAMDHT Monthly average of MDHTMAMDAT Monthly average of MDATMAMDLT Monthly average of MDLTMEHT Monthly extreme high temperature (ever record-

ed)MELT Monthly extreme low temperature (ever record-

ed).

Mean: Statistical mean over observation period (at least 20

years).Average: Average during one day and night.

A 300 Design principles and assumptions

301 Each class notation is related to a particular ice condition


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DETNORSKEVERITAS

that the vessel is expected to encounter. Relevant design iceconditions are as given in Table A1. In case intermediate iceconditions are relevant (see 103), nominal ice strength shall berelated to the selected nominal ice thickness.

302 Vessels with the class notation Icebreaker, and otherPOLARclass vessels are expected to encounter pressure ridg-es and other ice features of significantly greater thickness than

the average thicknesses specified in Table A1. Vessels with theclass notation POLARonly are assumed not to make repeatedramming attempts if the ice fails to break during the first (ac-cidental) ram unless the vessel's speed is kept well below thedesign ramming speed. Vessels with class notation Icebreak-ermay make several consecutive attempts to break the ice atmaximum ramming speed. The design speed in ice infestedwaters when ramming may occur, VRAM, shall be specified bythe builder. In general this speed shall not be taken less than:

VRAM= VB+ VH (m/s)

VB = specified continuous speed, when breaking maximumaverage ice thickness

VH

= speed addition in thinner ice

= hice(see Table A1).

In no case the design ramming speed shall be taken less than:

VRAM(minimum)

= 2.0 m/s (3.9 knots) for the notation POLAR-10

= 3.0 m/s (5.8 knots) for the notation POLAR-20

= 4.0 m/s (7.8 knots) for the notation POLAR-30.

For vessels with the class notation Icebreakerthe minimumspeed is 2 m/s (3.9 knots) but not less than 1.5 times the speedspecified above when POLARclass notation is also specified.

303 For POLAR class notations steel grades in exposedstructures shall be based on ambient air temperatures lowerthan those generally anticipated for world wide operation. Thedesign temperature for exposed structures is defined as thelowest mean daily average air temperature in the area of oper-ation. This temperature is considered to be comparable withthe lowest monthly mean temperature in the area of operationminus 2C. If operation is restricted to summer navigationthe lowest monthly mean temperature comparison may only beapplied to the warmer half of the month in question. For tem-perature definition, see 400 and Fig.1.

Steel grades in underwater hull structures shall be based on aminimum water temperature somewhat lower than expectedfor world wide operation.

304 For ICEclass notations no special consideration for lowambient air temperatures are given unless specified by thebuilder.

A 400 Definitions401 General symbols and terms are also given in Sec.1 B100.

402 Symbols

VRAM=design speed in m/s when ramming may occur, seealso 302

ice = nominal strength of ice in N/mm2, see Table A1

hice = average ice thickness in m, see Table A1

EKE= vessel's kinetic energy before ramming

= 1/2 (VRAM)2 (kNm)

a, = bow shape angles, see Fig.2CWL= vessel's water line area coefficient on LWL

s = stiffener spacing in m, measured along the plating.Stiffener web thickness may be deducted

l = stiffener span in m, measured along the top flange ofthe member.

The depth of stiffener on crossing panel may be de-ducted when deciding the span.

For curved stiffeners lmay be taken as the chord length

S = girder span in m. The web height of in-plane girdersmay be deducted

t = rule thickness of plating in mm

tk = corrosion addition in mm

tw = rule web thickness in mm

Z = rule section modulus in cm3

AW = rule web area in cm2, defined as the web thicknesstimes the web height including thickness of flanges

A = rule cross-sectional area in cm2

y = minimum upper yield stress of material in N/mm2.

NV-NS-steel may be taken as having y= 235 N/mm2

= nominal allowable bending stress in N/mm2due to lat-eral pressure

= nominal allowable shear stress in N/mm2.

403 External structureis defined, with respect to design tem-perature, as the plating with stiffening to a distance of 0.5 me-tre from the shell plating, exposed decks and exposed sides andends of superstructure and deckhouses.

404 Temperature terms (see also Fig.1):

Design temperatureis a reference temperature used as a crite-rion for the selection of steel grades.

Mean daily average temperatureis the statistical mean aver-age temperature for a specific calendar day, based on a number

of years of observations (= MDAT).

Monthly mean temperature is the average of the mean dailytemperature for the month in question (= MAMDAT).

Lowest mean daily temperatureis the lowest value on the an-

nual mean daily temperature curve for the area in question. Forseasonally restricted service the lowest value within the time ofoperation applies.

Lowest monthly mean temperatureis the monthly mean tem-perature for the coldest month of the year.

Table A1 Ice conditions

Class notation Type of ice encountered Nominal ice strength

ice(N/mm2)

Nominal ice thickness

hice(m)

Limiting impact conditions

ICE-05ICE-10ICE-15

Winter ice with pressure ridges4.25.67.0

0.51.01.5

No ramming anticipated

POLAR-10POLAR-20POLAR-30

Winter ice with pressure ridges and multi-yearice-floes and glacial ice inclusions

7.08.510.0

1.02.03.0

Accidental ramming

Icebreaker As above As above As above Repeated ramming


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Fig. 2Bow shape angles

405 The hull structure (shell plating with stiffening) to be re-inforced against local ice loads is divided into 6 different areas.The areas are defined as follows (see also Fig.3):

Bow area

Longitudinally from stem to a line parallel to and 0.04 L aft ofthe border line of flat side of hull forward. If the hull breadth isincreased over a limited length forward of the flat side the bowarea need normally not extend aftwards beyond the widest sec-tion of each waterline.

The bow area need not extend aftwards beyond 0.3 L from theforward perpendicular.

Vertically from a line defined by a distance zlmbelow BWL(aft) and the intersection between the keel line and the stemline (forward) to a line defined by the distances zua(aft) and zuf(forward) above LWL. For ships with an ice knife fitted, theline of the lower vertical extension may be drawn to a point

0.04 L aft of the upper end of the knife and further down to thebase line (see also Fig.3).

Fig. 3Extension of bow area

Stem area

The part of the bow area between the stem line and a line 0.06L aft of the stem line or 0.125 B outboard from the centre line,whichever is first reached.

Vertically from a line defined by a distance zlabelow BWL, toa line defined by a distance zuaabove LWL.

Bow side area

The part of the bow area not defined as the stem area.

Midship area

Longitudinally from the bow area to a line parallel to and 0.04L forward of the border line of flat side of hull aft, or to a line

0.2 L aft of amidships, whichever is the aftermost.

Vertically from a line defined by a distance zlmbelow BWL,to a line defined by a distance zuaabove LWL.

Bottom area

Longitudinally aft of 0.3 L from F.P. and transversely over theflat bottom including deadrise. For ships with bow ice knife,

the bottom area may be extended forward to the ice knife.Lower bow transition area

Transition area between the stem area and the side/bottom ar-eas.

Stern area

Longitudinally from the midship area and the lower transitionarea to the stern.

Vertically from a line defined by a distance zlabelow BWL, toa line defined by a distance zuaabove LWL.

Upper transition area

Over the full length of the vessel.

Above the bow/midship/stern areas a distance of zut.

LWL and BWL are defined in Sec.1 B200.

Values of zla,zlm,zua,zufand zutare given for various class no-tations in Table A2.

A 500 Documentation

501 LWL and BWL as well as the border line of flat sideshall be indicated on the shell expansion plan together with theice reinforced areas as given in Fig.4.

502 Maximum design ramming speed (VRAM) in ice infestedwaters as well as design speed for continuous ice breaking op-erations (VB) shall be stated on the midship section plan for

ships with class notations POLARor Icebreaker.

503 For documentation in connection with stability and wa-tertight integrity, see L300.

504 Applicable special limitations to the operation of thevessel in ice infested waters shall be stated in the ship's loadingmanual, see Pt.3 Ch.1 Sec.1 C100.

Possible limitations are:

allowable draughts, maximum and minimum

loading conditions with respect to strength and stability

ambient temperature

design speed

instruction for filling of ballast tanks505 Where ice exposed plating is fitted with a special wearaddition, the plate thickness including wear addition shall begiven on the shell expansion plan in addition to the net thick-ness required by the rules.

F.P.1m

BUTTOC

K

STEM

LINE

BASE LINE

LW L

LW L

CENTRE LINE

Zua

Zlm

Zuf

LWLBWL

0.3 L

0.04 L

Table A2 Vertical extent of ice reinforced areas

Class notation Parameters for vertical extent (m)

zla zlm1) zua zuf zut

ICE-05ICE-10ICE-15

1.72.24.6

1.11.63.7

0.81.01.9

1.31.62.5

0.30.50.7

POLAR-10POLAR-20POLAR-30

2.96.0

11.9

2.34.69.2

1.42.85.5

1.93.77.4

0.51.01.9

1) zlm(maximum) = the vertical distance from the BWL to thepoint on the frame contour amidshipswhere the tangent is at 45 degrees.


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DETNORSKEVERITAS

Fig. 4Ice reinforced areas

B. Materials and Corrosion Protection

B 100 Design temperatures

101 Steel grades to be used in hull structural members shallbe determined based on the design temperature for the struc-ture in question.

102 For external structures above BWL the design tempera-ture may normally be taken as the lowest mean daily averageair temperature in the area of operation. Unless a service re-striction notation is also given, limiting the navigation to spec-

ified areas and/or time of year, the design temperature shall notbe taken higher than in accordance with Table B1.

BORDE R LINE OF FLAT SIDE( at LWL )

LOWER TURN OF THE BILGE

BORDER LINE OF FLAT SIDE

TRANSITION SIDE/BOTTOM

UPPERTRANSITIONAREA

STERN AREA

BOW AREA

BOTTOMAREA

MIDSHIP AREA

LOWER BOWTRANSITION AREA

0.04L

0.06L

(max.)

0.3L

0.04L

0.2LA.P.

zut

zla

zua

zla

zlm z

ua

zut

zuf

LW L

BW L

F.P.

0.125B(max.)

Table B1 Design temperature for exposed structures

Class notation Design temperatureCorresponding ex-treme low tempera-

ture

POLAR-10 - 30C ( - 50C)POLAR-20 - 35C ( - 55C)

POLAR-30 - 40C ( - 60C)


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Amended, Rules for Ships, January 2005see Pt.0 Ch.1 Sec.3, July 2005 Pt.5 C

dnv ships for navigation in ice

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