HULL EQUIPMENT AND APPENDAGES

Transcription

1 RULES FOR CLASSIFICATION OF SHIPS NEWBUILDINGS HULL AND EQUIPMENT MAIN CLASS PART CHAPTER HULL EQUIPMENT AND APPENDAGES JANUARY 000 CONTENTS PAGE Sec. 1 General Requirements... 5 Sec. Sternframes, Rudders and Steering Gears... 6 Sec. Anchoring and Mooring Equipment... 8 Sec. Masts and Rigging... Sec. 5 Seats for Additional Lifting, Towing or Mooring Equipment... 5 App. A Additional Requirements for non duplicated Rudder Actuators... 8 Veritasveien 1, N-1 Høvik, Norway Tel.: Fax:

2 CHANGES IN THE RULES General The present edition of the rules includes additions and amendments decided by the board as of December 1999, and supersedes the January 1996 edition of the same chapter (including later amendments). The rule changes come into force 1 July 000. This chapter is valid until superseded by a revised chapter. Supplements will not be issued except for minor amendments and an updated list of corrections presented in Pt.0 Ch.1 Sec.. Pt.0 Ch.1 is normally revised 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 chapters printed Pt.0 Ch.1 Sec.1 to ensure that the chapter is current. In A0 "fibre ropes (W)" has been included in the list of items requiring DNV Product Certificate (NV) for materials, ISO 107: Type.1 C. Where the "(W)" indicates that a work's certificate (for materials, ISO 107 Type.1 B) from an approved manufacturer will normally be accepted. Sec.5 Seats for Additional Lifting, Towing or Mooring Equipment In A10 it is now stated that the crane pedestal flanges and bolts are only subject to approval when CRANE, DSV or Crane Vessel is requested. The amendment is made to remove any misunderstanding in regard to the material requirements and approval of pedestal flanges and bolts. In A01 the material requirement for pedestal top flanges has been removed. Main changes Sec. Anchoring and Mooring Equipment In A10 an additional sentence has been added indicating that if certification of materials is needed, voluntarily, then this will be done in accordance with A0. Corrections and Clarifications In addition to the above stated rule amendments, some detected errors have been corrected, and some clarifications have been made in the existing rule wording. Comments to the rules may be sent by to rules@dnv.com For subscription orders or information about subscription terms, please use distribution@dnv.com Comprehensive information about DNV and the Society's services is found at the Web site Det Norske Veritas Computer Typesetting (FM+SGML) by Det Norske Veritas PrintedinNorwaybyGCSAS. 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 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 that the maximum compensation shall never exceed USD 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 Det Norske Veritas.

3 Rules for Ships, January 000 Pt. Ch. Contents Page CONTENTS SEC. 1 GENERAL REQUIREMENTS... 5 A. Classification...5 A 100 Application...5 B. Definitions...5 B 100 Symbols...5 C. Documentation...5 C 100 General...5 SEC. STERNFRAMES, RUDDERS AND STEERING GEARS... 6 A. General...6 A 100 Introduction...6 A 00 Definitions...6 A 00 Documentation...7 B. Materials...8 B 100 Plates and sections...8 B 00 Forgings and castings...8 B 00 Bearing materials...8 B 00 Material certificates...8 B 500 Heat treatment...8 C. Arrangement and Details...8 C 100 Sternframes and rudders...8 C 00 Steering gears...9 D. Design Loads and Stress Analysis...9 D 100 Rudder force and rudder torque, general...9 D 00 Rudders with stepped contours...10 D 00 Stress analysis...11 E. Sternframes and Rudder Horns...11 E 100 General...11 E 00 Propeller posts...11 E 00 Sole pieces...1 E 00 Rudder horns...1 F. Rudders...1 F 100 General arrangement and details...1 F 00 Rudder plating...1 F 00 Rudder bending...1 F 00 Web plates...15 F 500 Single plate rudders...15 F 600 Mounting of rudder...15 G. Rudder Stocks and Shafts...15 G 100 General...15 G 00 Rudder stock with couplings...16 G 00 Rudder shaft...18 G 00 Bearings and pintles...19 H. Propeller Nozzles...0 H 100 General...0 H 00 Plating...0 H 00 Nozzle ring stiffness...0 H 00 Welding...0 H 500 Supports...1 I. Propeller Shaft Brackets...1 I 100 General...1 I 00 Arrangement...1 I 00 Struts...1 I 00 Welding...1 I 500 Material...1 I 600 Testing...1 J. Steering Gears...1 J 100 Arrangement and performance...1 J 00 Power actuating system, general requirements... J 00 Piping systems, relief valve arrangements... J 00 Rudder actuator... J 500 Steering gear control and monitoring systems, general requirements...5 J 600 Control gear for steering motors...5 J 700 Indications and alarms...5 J 800 Power supply and distribution...5 J 900 Emergency power supply...6 J 1000 Operating instructions...6 J 1100 Additional requirements for oil carriers, chemical carriers and liquefied gas carriers of tons gross and upwards...6 K. Testing... 6 K 100 Sternframes...6 K 00 Rudders and rudder stock connections...7 K 00 Steering gears...7 K 00 Trials...7 SEC. ANCHORING AND MOORING EQUIPMENT... 8 A. General... 8 A 100 Introduction...8 A 00 Documentation...8 A 00 Assumptions...8 B. Structural Arrangement for Anchoring Equipment... 8 B 100 General...8 C. Equipment Specification... 9 C 100 Equipment number...9 C 00 Equipment tables...0 D. Anchors... 1 D 100 General...1 D 00 Materials...1 D 00 Anchor shackle...1 D 00 Testing... D 500 Additional requirements for H.H.P. ( High Holding Power ) anchors... D 600 Identification... E. Anchor Chain Cables... E 100 General... E 00 Materials... E 00 Heat treatment and material testing...5 E 00 Breaking test...5 E 500 Proof test...5 E 600 Tolerances...5 E 700 Identification...6 E 800 Repair of defects...6 F. Windlass and Chain Stoppers... 8 F 100 General design...8 F 00 Materials...8 F 00 Testing...9 G. Towlines and Mooring Lines... 9 G 100 General...9 G 00 Materials...9 G 00 Testing of steel wire ropes...9 G 00 Testing of natural fibre ropes...0 G 500 Mooring Winches...1 SEC. MASTS AND RIGGING... A. General... A 100 Introduction... A 00 Assumptions... A 00 Definitions... A 00 Documentation... B. Materials and Welding... B 100 Materials... B 00 Welding... C. Arrangement and Support... C 100 Masts and posts... C 00 Standing rigging...

4 Rules for Ships, January 000 Pt. Ch. Contents Page D. Design and Scantlings... D 100 General... D 00 Unstayed masts and posts with derricks... D 00 Stayed masts or posts with derricks with a lifting capacity not exceeding 10 t... D 00 Stayed masts of posts with derricks with a lifting capacity of 10 t or more, but not exceeding 0 t... D 500 Stayed masts without derricks... D 600 Shrouds... SEC. 5 SEATS FOR ADDITIONAL LIFTING, TOWING OR MOORING EQUIPMENT... 5 A. Crane Pedestals and Miscellaneous Lifting Posts...5 A 100 Introduction...5 A 00 Documentation...5 A 00 Materials and welding...5 A 00 Arrangement...5 A 500 Design loads...5 A 600 Allowable stresses...6 B. Seatings for Winches, Windlasses and other Pulling Accessories...6 B 100 Introduction....6 B 00 Documentation...6 B 00 Design loads...7 B 00 Calculation of stresses...7 B 500 Allowable stresses. Materials...7 APP. A ADDITIONAL REQUIREMENTS FOR NON DUPLICATED RUDDER ACTUATORS... 8 A. Introduction... 8 A 100 Scope...8 B. Materials...8 B 100 Special Requirements...8 C. Design... 8 C 100 Design pressure...8 C 00 Analysis...8 C 00 Dynamic loads for fatigue and fracture mechanics analysis...8 C 00 Allowable stresses...8 C 500 Burst test...8 D. Construction Details...8 D 100 General...8 D 00 Welds...8 D 00 Oil seals...8 D 00 Isolating valves...8 D 500 Relief valves...9 E. Testing... 9 E 100 Non-destructive testing...9 E 00 Other testing...9

5 Rules for Ships, January 000 Pt. Ch. Sec.1 Page 5 SECTION 1 GENERAL REQUIREMENTS A. Classification A 100 Application 101 The Rules in this chapter apply to steering arrangement and anchoring, mooring and load handling equipment. 10 Necessary strengthening of the hull structure due to loads imposed by the equipment and installations are given where appropriate. B 100 Symbols 101 L = Rulelengthinm 1) B = Rulebreadthinm 1) B. Definitions D = Ruledepthinm 1) T = Rule draught in m 1) = Rule displacement in t 1) C B = Rule block coefficient 1) V = maximum service speed in knots on draught T 1) For details see Ch.1 Sec.1 B C. Documentation C 100 General 101 Plans and particulars to be submitted for approval or information are specified in the respective sections of this chapter. 10 For instrumentation and automation, including computer based control and monitoring, see Pt. Ch.9 Sec.1.

6 Rules for Ships, January 000 Pt. Ch. Sec. Page 6 SECTION STERNFRAMES, RUDDERS AND STEERING GEARS A. General A 100 Introduction 101 Requirements to side thrusters and other appliances intended for manoeuvring or positioning purposes are given in Pt. Ch.5. A 00 Definitions 01 Main steering gear means the machinery, rudder actuator(s), the steering gear power units, if any, and ancillary equipment and the means of applying torque to the rudder stock (e.g. tiller or quadrant) necessary for effecting movement of the rudder for the purpose of steering the ship under normal service conditions. 0 Auxiliary steering gear means the equipment other than any part of the main steering gear necessary to steer the ship in the event of failure of the main steering gear but not including the tiller, quadrant or components serving the same purpose. 0 Steering gear control system means the equipment by which orders are transmitted from the navigating bridge to the steering gear power units. Steering gear control systems comprise transmitters, receivers, hydraulic control pumps and their associated motors, motor controllers, piping and cables. 0 Rudder actuator means the component which converts directly hydraulic pressure into mechanical action to move the rudder. 05 Steering gear power unit means: 1) in the case of electric steering gear, an electric motor and its associated electrical equipment; ) in the case of electrohydraulic steering gear, an electric motor and its associated electrical equipment and connected pump; ) in the case of other hydraulic steering gear, a driving engine and connected pump. 06 Power actuating system means the hydraulic equipment provided for supplying power to turn the rudder stock, comprising a steering gear power unit or units, together with the associated pipes and fittings, and a rudder actuator. The power actuating systems may share common mechanical components, i.e. tiller quadrant and rudder stock, or components serving the same purpose. 07 Maximum ahead service speed is the maximum speed corresponding to maximum nominal shaft RPM and corresponding engine MCR in service at sea on summer load waterline. 08 Maximum astern speed is the speed which it is estimated the ship can attain at the designed maximum astern power at the deepest seagoing draught. 09 Maximum working pressure means the maximum oil pressure in the system when the steering gear is operated to comply with J For terms redundancy and independence see Pt. Ch.1 Sec Some terms used for rudder, rudder stock and supporting structure are shown in Fig. 1.

7 Rules for Ships, January 000 Pt. Ch. Sec. Page 7 Fig. 1 Rudders 1 Symbols: f 1 = material factor, see B p m = maximum bearing surface pressure, see B F R = design rudder force, see D M TR = design rudder torque, see D A = total area in m of rudder blade H = mean rudder height in m. A 00 Documentation 01 Plans etc. as specified below are to be submitted for approval: sternframe, horn and propeller brackets, outline of the propeller rudder including details of bearings, shaft, pintles and rudder lock arrangement rudder stock including details of couplings, bolts and keys rudder carrier sectional drawing of rudder actuator dimension drawings for torque transmitting parts and parts subject to internal hydraulic pressure foundation bolts and chocks rudder stoppers piping (and function) diagram according to Pt. Ch.6 schematic diagrams for: power supply arrangement motor control systems (detailed requirements for the diagrams are given in Pt. Ch.8 for electrical installations) calculations according to K0 and K0 if sea trials are planned to be carried out in a load condition not providing fully submerged rudder. Such calculations are at least to include evaluation of expected trial loads (torque and support reaction forces) on the actuator versus calculated rudder torque fully submerged and at trial conditions taking into account the friction losses and any back pressure in the return side. The plans are to give full details of scantlings and arrangement as well as data necessary for verifying scantling calculations together with proposed rated torque. Set pressure for all relief valves are to be specified. Material specifications and particulars about heat treatment are also required. 0 For important components of welded construction (e.g. rudder, rudder stock, tiller), full details of the joints, welding procedure, filler metal and heat treatment after welding are to bespecifiedontheplans. 0 Procedure for stress relieving of nodular cast iron and cast steel parts, when dimensional stability is important (such as tiller and rotor, see B50), is to be specified on the plans. 0 Plans of the following items are to be submitted for information: general arrangement drawings of steering gear and steering gear compartment installation instructions for steering gear (inclusive fitting to rudder stock) locking or brake arrangement steering gear relief valve discharge characteristics (pressure-flow diagram) total delivery capacity of steering gear hydraulic pumps operation instructions (according to J1000). 05 Steering gear manufacturers who intend their product to comply with the requirements of the IMO Guidelines for nonduplicated rudder actuators, see Appendix A, are to submit documentation as specified in the guidelines when plans are forwarded for approval. 06 For instrumentation and automation, including computer based control and monitoring, see Pt. Ch.9 Sec.1.

8 Rules for Ships, January 000 Pt. Ch. Sec. Page 8 B. Materials B 100 Plates and sections 101 Selection of material grades for plates and sections is to be based on material thickness. NV-steel grades as given in Table B1 will normally be accepted. Table B1 Plate material grades Thickness in mm Normal strength structural steel High strength structural steel t 0 A A 0 < t 0 B A 0 < t 10 D D 10 The material factor f 1 included in the various formulae for structures may be taken as: f 1 = 1,0 for NV-NS steel f 1 =1,08forNV-7steel f 1 =1,8forNV-steel f 1 =1,9forNV-6steel f 1 =1,forNV-0steel B 00 Forgings and castings 01 Rudder stocks, pintles, coupling bolts, keys and cast parts of rudders are to be made of rolled, forged or cast carbon manganese steel in accordance with Pt.. For rudder stocks, pintles, keys and bolts the minimum yield stress is not to be less than 00 N/mm. 0 Nodular cast iron may be accepted in certain parts after special considerations. Materials with minimum specified tensile strength lower than 00 N/mm or higher than 900 N/mm will normally not be accepted in rudder stocks, axle or pintles, keys and bolts. 0 Ram cylinders, pressure housings of rotary vane type actuators, hydraulic power piping, valves, flanges and fittings, and all steering gear components transmitting mechanical forces to the rudder stock (such as tillers, quadrants, or similar components) are to be of steel or other approved ductile material, duly tested in accordance with the requirements of Pt.. In general, such material is to have an elongation of not less than 1 % nor a tensile strength in excess of 650 N/mm. Grey cast iron may be accepted for redundant parts with low stress level, excluding cylinders, upon special consideration. 0 The material factor f 1 for forgings (including rolled round bars) and castings may be taken as: f 1 σ æ f ö a = è5ø σ f = minimum upper yield stress in N/mm, not to be taken greater than 70% of the ultimate tensile strength. If not specified on the drawings, σ f is taken as 50% of the ultimate tensile strength. a = 0,75 for σ f > 5 = 1,0 for σ f < 5 05 Before significant reductions in rudder stock diameter due to the application of steels with yield stresses exceeding 5 N/mm are granted, the Society may require the evaluation of the rudder stock deformations. Large deformations should be avoided in order to avoid excessive edge pressures in way of bearings. The slope of the stock should be related to the bearing clearance, see G05. B 00 Bearing materials 01 Bearing materials for bushings are to be stainless steel, bronze, white metal, synthetic material or lignum vitae. Stainless steel or bronze bushings are to be used in an approved combination with steel or bronze liners on the axle, pintle or stock. The difference in hardness of bushing and liners is not to be less than 65 Brinell. 1% Chromium steel is to be avoided. 0 Synthetic bearing bushing materials are to be of an approved type. For this type of bushing, adequate supply of lubrication to the bearing for cooling/lubrication purposes is to be provided. 0 The maximum surface pressure p m for the various bearing combinations is to be taken as given in Table B. Table B Bearing surface pressures Bearing material p m (kn/m ) Lignum vitae 500 White metal, oil lubricated 500 Synthetic material with hardness between 60 and70shored 5500 ) Steel 1) and bronze and hot-pressed bronzegraphite materials ) Stainless and wear-resistant steel in an approved combination with stock liner ) Surface pressure exceeding the specified limit may be accepted for rudder bearing applications in accordance with bearing manufacturer's specification and when verified by tests and/or service experience. Surface pressure exceeding the values in Table B may be accepted for rudder actuator bearings in accordance with bearing manufacturer's specification and when verified by tests. B 00 Material certificates 01 «Det Norske Veritas Product Certificate» (NV) will be required for: sternframe structural parts rudder structural parts rudder shaft or pintles rudder stock rudder carrier tiller or rotor crosshead cylinders/rams rotor housing manifolds. 0 Works certificate (W) will be accepted for: bolts and pins stoppers steering gear covers steering gear pistons. B 500 Heat treatment 501 Fabricated parts in the steering gear are to be fully annealed after welding. 50 Nodular cast iron and cast steel parts for transmission of rudder torque by means of keyless conical or cylindrical connections are to be stress relieved. C. Arrangement and Details C 100 Sternframes and rudders 101 Relevant types of rudder arrangements are shown in Fig. 1. Other combinations of couplings and bearings may be applied. 10 Suitable arrangement to prevent the rudder from lifting and accidental unshipping is to be provided. The arrangement

9 Rules for Ships, January 000 Pt. Ch. Sec. Page 9 is to effectively limit vertical movement of rudder in case of extreme (accidental) vertical load on rudder. 10 Effective means are to be provided for supporting the weight of the rudder without excessive bearing pressure, e.g. by a rudder carrier attached to the upper part of the rudder stock. The hull structure in way of the rudder carrier is to be suitably strengthened. 10 If the rudder trunk is open to the sea, a seal or stuffing box is to be fitted above the deepest load waterline, to prevent water from entering the steering gear compartment and the lubricant from being washed away from the rudder carrier. An additional seal of approved type is required when the rudder carrier is below the summer load waterline. 105 Guidance note: The after body should be so shaped as to ensure a proper flow of water to the propeller, and so as to prevent uneven formation of eddies as far as possible. The apex of the waterlines in front of the propeller should have the least possible radius, together with a relatively small angle φ. Plane or approximately plane parts above the propeller tip should be avoided. The strength of pressure impulses from propeller to hull will normally decrease with increasing clearances. However, even with large clearances to the propeller, a hull may be exposed to strong impulses if the propeller is subject to heavy cavitation. For a moderately cavitating propeller, the following minimum clearances are proposed (see Table C1 and Fig. ): Table C1 Minimum clearances For single screw ships: For twin screw ships: a 0, R (m) b (0,7 0,0Z P )R (m) c (0,8 0,0 Z P )R (m) c (0,6 0,0 Z P )R (m) e 0,07 R (m) R Z P = propeller radius in m = number of propeller blades. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e--- TL B A = C æ 100 B --- ö (m ) èlø For ships which frequently manoeuvre in harbours, canals or other narrow waters, the rudder area determined by the formula should be increased. For ships with a streamlined rudder post, half of the lateral area of the post may be included in the rudder area. For ships with a rudder horn, the whole area of the horn laying below a horizontal line from the top of the rudder may be included. Rudders not working directly behind a propeller should have the area as given above, increased by at least 0%. Rudders with special profiles or special configurations (e.g. flaps or nozzles) giving increased efficiency may have smaller total areas. For ships with large freeboard and/or high continuous superstructures an increase of the rudder area ought to be considered. Larger rudder area may result in excessive heeling angle when using the rudder in extreme position at full speed ahead. This is particularly relevant for passenger vessels, ferries, vehicle ro/ro carriers and other vessels where the combination of speed, draught, vertical centre of gravity and metacentric height may result in excessive heeling angle in case of smaller turning circles. For estimating the result angle of heel, reference is made to Pt.5 Ch. Sec. K00. In cases where the resulting angle of heel may exceed 10 degrees, the Master should be provided with warning about this in the stability manual. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e Guidance note: In order to minimise vibrations, the balancing and design of the rudders should be carried out as follows: the balanced portion should not be greater than % of the total area of the rudder the length of the balanced part at any horizontal section should nowhere be greater than 5% of the total length of the rudder the widest part of the rudder section should preferably be at least 0% aft of the leading edge of the rudder section considered. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e Over-balanced rudders are subject to special consideration with respect to type of steering gear and risk of an unexpected and uncontrolled sudden large movement of rudder causing severe change of ship's pre-set course. See J106. Guidance note: A rudder shall be considered over-balanced, when balanced portion exceed 0% in any actual load condition. Special rudder types, such as flap rudders, are subject to special consideration. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e--- C 00 Steering gears 01 For arrangement and details of steering gear see subsection J. Fig. Propeller clearances 106 Guidance note: Rudders (one or more) working directly behind a propeller should preferably have a total area not less than: D. Design Loads and Stress Analysis D 100 Rudder force and rudder torque, general 101 The rudder force upon which the rudder scantlings are to be based is to be determined from the following formula: F R = 0,0 k 1 k k AV (kn) A = area of rudder blade in m, including area of flap. = vertical projected area of nozzle rudder

10 Rules for Ships, January 000 Pt. Ch. Sec. Page 10 k 1 = coefficient depending on rudder profile type (see Fig. ): For special rudder designs (such as flap rudders) direct calculations of rudder torque, supported by measurements on similar rudders, may be considered as basis for rudder torque estimation. Table D1 Rudder profile type - coefficient Profile type Ahead Astern NACA - Göttingen 1,1 0,8 Hollow profile 1) 1,5 0,9 Flatsided 1,1 0,9 Profile with «fish tail» 1, 0,8 Rudder with flap 1,65 1, Nozzle rudder 1,9 1,5 1) Profile where the width somewhere along the length is 75% or less of the width of a flat side profile with same nose radius and a straight line tangent to after end k = coefficient depending on rudder/nozzle arrangement = 1,0 in general = 0,8 for rudders which at no angle of helm work in the propeller slip stream = 1,15 for rudders behind a fixed propeller nozzle H k = not to be taken greater than A t H = mean height in m of the rudder area. Mean height and mean breadth B of rudder area to be calculated as showninfig. A t = total area of rudder blade in m including area of flap and area of rudder post or rudder horn, if any, within the height H. V = maximum service speed (knots) with the ship on summer load waterline. When the speed is less than 10 knots, V is to be replaced by the expression: V + 0 V min = For the astern condition the maximum astern speed is to be used, however, in no case less than: V astern =0,5V The maximum service speed corresponds to the maximum continuous rating (MCR) of the engine. In special ship types (such as tugs) the maximum output of the propelling machinery may exceed MCR by more than 15%. In such cases V is to be increased by the following percentage: Table D Percentage increase in MCR vs V Maximum engine output above normal (%) V increase (%) The rule rudder torque is to be calculated for both the ahead and astern condition according to the formula: M TR =F R x e (knm) = minimum 0,1 F R B F R = as given in 101 for ahead and astern conditions x e = B (α -k) (m) B = mean breadth of rudder area, see Fig. α = 0, for ahead condition = 0,66 for astern condition k = A F A A F = area in m of the portion of the rudder blade area situated ahead of the center line of the rudder stock A = rudder blade area as given in 101. Fig. Rudder profiles D 00 Rudders with stepped contours 01 The total rudder force F R is to be calculated according to 101, with height and area taken for the whole rudder. 0 The pressure distribution over the rudder area may be determined by dividing the rudder into relevant rectangular or trapezoidal areas, see e.g. Fig. 5. The rule rudder torque may be determined by: M TR = = minimum 0,1 F R x em n = number of parts i = integer F Ri = A i F A R x ei = B i (α -k i ) n ( A x em = i B i ) å A i = 1 A i = partial area in m B i = mean breadth of part area, see Fig. α = as given in10 For parts of a rudder behind a fixed structure such as a rudder horn: α = 0,5 for ahead condition = 0,55 for astern condition k i = A if A i A if = rudder part area forward of rudder stock centre line, see Fig. 5 F R andaasgivenin10. n å i = 1 ( F Ri x ei ) (knm)

11 Rules for Ships, January 000 Pt. Ch. Sec. Page 11 E. Sternframes and Rudder Horns Fig. Rudder dimensions E100 General 101 Sternframes and rudder horns are to be effectively attached to the surrounding hull structures. In particular the stern bearing or vertical coupling flange for rudder axle is to be appropriately attached to the transom floor adjacent to the rudder stock. For semi-spade and spade rudder arrangements structural continuity in the transverse as well as the longitudinal direction is to be specially observed. 10 Cast steel sternframes and welded sternframes are to be strengthened by transverse webs. Castings are to be of simple design, and sudden changes of section are to be avoided. Where shell plating, floors or other structural parts are welded to the sternframe, there is to be a gradual thickness reduction towards the joint. Steel forgings and castings for sternframes, rudder horns and rudders are to be in accordance with the requirements in Pt. Ch. Sec.5 and Sec.7 for general applications. 10 Depending on casting facilities, larger cast steel propeller posts are to be made in two or more pieces. Sufficient strength is to be maintained at connections. The plates of welded propeller posts may be welded to a suitable steel bar at the after end of the propeller post. 10 Stresses determined by direct calculations as indicated in D00 are normally not to exceed the following values: Normal stress: σ =80f 1 (N/mm ) Shear stress : τ =50f 1 (N/mm ) Equivalent stress : σ e =10f 1 (N/mm ) σ e = σ 1 + σ σ 1 σ + τ E 00 Propeller posts 01 The boss thickness at the bore for the stern tube is not to be less than: t = 5 d p 60 (mm) Fig. 5 Rudder area distribution D 00 Stress analysis 01 The rudder force and resulting rudder torque as given in 100 and 00, causes bending moments and shear forces in the rudder body, bending moments and torques in the rudder stock, supporting forces in pintle bearings and rudder stock bearings and bending moments, shear forces and torques in rudder horns and heel pieces. The bending moments, shear forces and torques as well as the reaction forces are to be determined by a direct calculation or by approximate simplified formulae as given in the following. For rudders supported by sole pieces or rudder horns these structures are to be included in the calculation model in order to account for the elastic support of the rudder body. Acceptable direct calculation methods are given in Classification Note No..1 Strength Analysis of Rudder Arrangements. For rudder horns, see also E0. 0 Allowable stresses for the various strength members are given in subsections E to J. For evaluation of angular deflections, see B05 and G05. d p = rule diameter of propeller shaft in mm. 0 The scantlings of fabricated propeller posts are not to be less than: l = 5 L (mm) b = 7 L (mm), L t = (mm) f 1 l, bandtareasshowninfig.6alt.i. Where the section adopted differs from the above, the section modulus about the longitudinal axis is not to be less than: 1, 5L L Z W = (cm ) f 1 0 The scantlings of cast steel propeller posts are not to be less than: l = 0 L (mm) b = 0 L (mm)

12 Rules for Ships, January 000 Pt. Ch. Sec. Page 1 L t 1 = (mm) f 1, 7 L t = (mm) f 1 l, b,t 1 and t are as shown in Fig. 6 Alt. II. Where the section adopted differs from the above, the section modulus about the longitudinal axis is not to be less than: Z C = 1L, L f 1 (cm ) When calculating the section modulus, adjoining shell plates within a width equal to 5 L from the after end of the post may be included. 0 The section modulus of the sole piece about a horizontal axis abaft the forward edge of the propeller post is in no place to be less than: Z 1 Z = (cm ) 0 The sectional area of the sole piece is not to be less than: A S 0, 1F R = (cm ) f 1 E 00 Rudder horns 01 The section modulus requirement of the rudder horn about a longitudinal axis is given by: Z 15M V l h = (cm ) y h f 1 M V = n å i = 1 F Ri y ei l h = vertical distance in m from the middle of the horn pintle bearing to the section in question y h = vertical distance in m from the middle of the rule pintle bearing to the middle of the neck bearing F Ri = part of rudder force acting on the i-th part of the rudder area, see D0 y ei = vertical distance in m from the centroid of the i-th part of the rudder area to the middle of the neck bearing n = number of rudder parts Fig. 6 Propeller posts E 00 Sole pieces 01 The sole piece is to be sloped in order to avoid pressure from keel blocks when docking. The sole piece is to extend at least two frame spaces forward of forward edge of the propeller boss. The cross section of this extended part may be gradually reduced to the cross section necessary for an efficient connection to the plate keel. 0 The section modulus requirement of the sole piece about a vertical axis abaft the forward edge of the propeller post is given by: Z 1 = 6, 5F R l s f 1 (cm ) l s = distance in m from the centre line of the rudder stock to the section in question. l s is not to be taken less than half the free length of the sole piece. For the straight part of the rudder horn the section modulus may be taken for the total sectional area of the horn. When the connection between the rudder horn and the hull structure is designed as a curved transition into the hull plating the section modulus requirement as given above is to be satisfied by the transverse web plates as follows: n b i ti å i = 1 Z W = Z, 6000b max n = number of transverse webs b i = effective breadth in mm of web no. i. (including the flange thickness) t i = thickness in mm of web no. i b max =largestb i. Z, b i and b max are to be taken at a horizontal section 0,7 r above the point where the curved transition starts (r = radius of curved part, see Fig. 7). The formula for Z W is based on the material in web plates and shell plate being of the same strength. For a cast rudder horn any vertical extension of the side plating (see Fig. 8) may be included in the section modulus.

13 Rules for Ships, January 000 Pt. Ch. Sec. Page 1 0 The rudder horn thickness requirement is given by: t = 110kF R e h (mm) f 1 A S k = ( Z Z A ) e h A S = horizontal projected distance in m from the centre line of the horn pintle to the centroid of A S = area in cm in horizontal section enclosed by the horn. For a curved transition between horn plating and shell plating the thickness of the transition zone plate is not to be less than: s r Z A Z 015s, ( 0) t c = Z (mm) r Z A = spacing between transverse webs in mm = radius of curved transition in mm = section modulus at section immediately below the transition zone = section modulus requirement in same section, as given in The vertical parts of the rudder horn participating in the strength against transverse shear are to have a total area in horizontal section given by: A W = C 0, F R (cm ) f 1 Fig. 7 Curved plate transition rudder horn/shell plating Fig. 8 Curved cast transition rudder horn/shell plating C = æ ( A + A 1 H )A H ö ç A at upper end of horn è ø = 1,0 at lower end A H = areaofhorninm. At intermediate sections A H should be taken for part of horn below section A = totalareaofrudderinm. In a curved transition zone the thickness of the transverse web plates is not to be less than: t r =0,8t c (mm) t c = thickness of curved plate In the transition zone the curved shell plate is to be welded to the web plates by full penetration weld or by a fillet weld with throat thickness not less than: t = 0,55 f 1 t r (mm) 0 A direct stress analysis of the rudder horn, if carried out, is to be based on a finite element method. For a curved transition to the hull structure the maximum allowable normal and equivalent stresses as given in 10, may in the curved plate be increased to: σ = 10 f 1 N/mm σ e =f 1 N/mm A fine-mesh finite element calculation will be considered as an acceptable method. In the web plates the normal stresses should not exceed σ = 10 f 1 N/mm. 05 For a curved transition between the horn side plating and the shell plating, the side plate thicknesses given in 01 to 0 are to be extended to the upper tangent line of the curved part.

14 Rules for Ships, January 000 Pt. Ch. Sec. Page 1 The transverse web thicknesses are to be kept to the same level and are to be welded to the floors above. No notches, scallops or other openings are to be taken in the transition area. The alternative design is to carry the side plating of the rudder horn through the shell plate and connect it to longitudinal girders (see Fig. 9), or weld it to the shell plate in line with longitudinal girders. In the latter case the welds below and above the shell plate are to be full penetration welds, and the shell plate is to be specially checked for lamellar tearing. The transverse girders are to be connected to/supported by transverse floors. Floor plating welded to rudder horn web plates is to have a thickness not less than 75% of the web plate thickness. 06 The lower end of the rudder horn is to be covered by a horizontal plate with thickness not less than the side plating. Guidance note: In case cover plates are permanently welded to the side plating, it is recommended to arrange peep holes for inspection of securing of nuts and pintles. ---e-n-d---of---g-u-i-d-a-n-c-e---n-o-t-e Great care is to be taken in highly stressed connections such as: welds between rudder side plating and upper heavy part of rudder at stock coupling welds around cut-outs in semi-spade rudders and openings for demounting of cone coupling and pintles. 10 Welds between plates and heavy pieces (cast or very thick plating) are to be made as full penetration welds, preferably to cast or welded on ribs. Where back welding is impossible welding is to be performed against backing bar or equivalent. 105 Webs are to be connected to the side plates in accordance with Ch.1 Sec.1. Slot-welding is to be limited as far as possible. Horizontal slots in side plating in areas with large bending stresses are to be completely filled by welding. Normally, slots of length 75 mm and a breadth of t (where t = rudder plate thickness), with a distance of 15 mm between ends of slots, will be accepted. In areas where slots are required to be completely filled by welding, more narrow slots with inclined sides (minimum 15 to the vertical) and a minimum opening of 6 mm at bottom may be used. A continuous slot weld may, however, in such cases be more practical. 106 Plate edges at corners in cut-outs and openings in rudder side plating are to be ground smooth in those parts of the rudder where high stresses will occur. 107 Means for draining the rudder completely after pressure testing or possible leakages is to be provided. Drain plugs are to be fitted with efficient packing. 108 Internal surfaces are to be covered by a corrosion-resistant coating after pressure-testing and possible stress-relieving. 109 For testing of rudder, see K. F 00 Rudder plating 01 The thickness requirement of side, top and bottom plating is given by: t 5, k a s T 0, 1F R = , 5 (mm) f A 1 Fig. 9 Shell plating connected to longitudinal girders in line with rudder horn sides k a = 110,, 5æ s èb -- ö ø maximum 1,0 F. Rudders F 100 General arrangement and details 101 Rudders are to be double plate type with internal vertical and horizontal web plates. The rudder body is to be stiffened by horizontal and vertical webs enabling it to act as a girder in bending. Single plate rudders may be applied to smaller vessels of special design and with service restrictions, see All rudder bearings are to be accessible for measuring of wear without lifting or unshipping the rudder. s b = the smaller of the distances between the horizontal or the vertical web plates in m = the larger of the distances between the horizontal or the vertical web plates in m. In no case the thickness is to be less than the minimum side plate thickness as given in Ch.1 Sec.7 C101 or Ch. Sec.6 C10. F 00 Rudder bending 01 Bending moments in the rudder are to be determined by direct calculations as indicated in D00. For some common rudder types the following approximate formulae may be applied:

15 Rules for Ships, January 000 Pt. Ch. Sec. Page 15 For balanced rudders with heel support: M max =0,15F R H (knm) For semi-spade rudders at the horn pintle: For spade rudders: A 1 h s = areainm of the rudder part below the cross-section in question = vertical distance in m from the centroid of the rudder area A 1 to the section in question. 0 The nominal bending stress distribution in the rudder maynormallybedeterminedonthebasisofaneffectivesection modulus to be estimated for side plating and web plates within 0% of the net length (cut-outs or openings deducted) of the rudder profile. The effective length is not to be taken greater than,5 d s (d s = rudder stock diameter at neck bearing) or the length of the flange coupling at the top of the rudder. Special attention to be paid to open flange couplings on the rudder. The external transverse brackets will normally have to be supplied with heavy flanges to obtain the necessary section modulus of the rudder immediately below the flange. As an alternative the bending stress distribution in the rudder may be determined by a finite element calculation. 0 Nominal bending stresses calculated as given in 01 and 0 are not to exceed: σ M M max = F R A 1 h s (knm) A = 110 f 1 N/mm in general = 75 f 1 N/mm at sections in way of cut-outs (e.g. semispade rudders) in the rudder. In case of openings in side plate for access to cone coupling or pintle nut, σ =90f 1 to be applied when the corner radius is greater than 0,15 l ( l = length of opening), σ =60f 1 when the radius is smaller. F00 Webplates 01 The thickness of vertical and horizontal webs is not to be less than 70% of the thickness requirement given in 00, in no case less than 8 mm. 0 The total web area requirement for the vertical webs is given by: A W = = F R A 1 h s (knm) A P (cm ) 5f 1 P = æ h 06, ö FR for balanced rudder è Hø with heel support = h ---- F H R for spade rudder or lower part of semi-spade rudder h 1 = height in m of the smaller of rudder parts below or above the cross-section in question h = height in m of the rudder part below the cross section in question. Shear stresses in web plates determined by direct stress calculations are not to exceed: τ =50f 1 (N/mm ) Equivalent stress is not to exceed: σ e = σ b + τ = 10 f 1 N/mm in rudder-blades without cut-outs = 100 f 1 N/mm in rudder-blades with cut-outs. F 500 Single plate rudders 501 Mainpiece diameter The mainpiece diameter is calculated according to G01. For spade rudders the lower third may taper down to 0,75 times stock diameter. When calculating the rudder force F R as given in D101 the factor k 1 may be taken equal to 1,0 in ahead condition. 50 Blade thickness The blade thickness is not to be less than: t b =1,5sV+,5 (mm) s = spacing of stiffening arms in metres, not to exceed 1 m V = speed in knots, see D Arms The thickness of the arms is not to be less than the blade thickness: t a =t b The section modulus is not to be less than: Z a =0,5sC 1 V (cm ) C 1 = horizontal distance from the aft edge of the rudder to the centre line of the rudder stock in metres. For higher tensile steels the material factor according to B100 is to be used correspondingly. F 600 Mounting of rudder 601 For rudder with continuous shaft it is to be checked that the rudder shaft has the right position in relation to the upper coupling, both longitudinally and transversely, when the lower tapered part of the rudder axle bears hard at the heel. The rudder shaft is to be securely fastened at the heel before the coupling bolts at the upper end are fitted. 60 Before final mounting of rudder pintles, the contact between conical surfaces of pintles and their housings is to be checked by marking with Prussian blue or by similar method. When mounting the pintles, care is to be taken to ensure that packings will not obstruct the contact between mating surfaces. The pintle and its nut are to be so secured that they cannot move relatively to each other. G. Rudder Stocks and Shafts G 100 General 101 Stresses determined by direct calculations as indicated in D00 are normally to give equivalent stress σ e not exceeding 118 f 1 N/mm and shear stress τ not exceeding 68 f 1 N/ mm. The equivalent stress for axles in combined bending and torsion may be taken as: σ e = σ + τ (N/mm ) σ = bending stress in N/mm τ = torsional stress in N/mm. 10 The requirements to diameters are applicable regardless of liner. Both ahead and astern conditions are to be considered.

16 Rules for Ships, January 000 Pt. Ch. Sec. Page A rudder stock cone coupling connection without hydraulic arrangement for mounting and dismounting is not to be applied for spade rudders. 10 An effective sealing is to be provided at each end of the cone coupling. G 00 Rudder stock with couplings 01 The diameter requirement is given by: k b = 1 above the rudder carrier, except where the rudder stock is subjected to bending moment induced by the rudder actuator (bearing arrangement versus rudder stock bending deflections, or actuator forces acting on tiller) 1 M = 1 -- æ B ö at arbitrary cross-section èm TR ø M B = calculated bending moment in knm at the section in question. If direct calculations of bending moment distribution are not carried out, M B at the neck bearing or the rudder coupling may be taken as follows: for balanced rudder with heel support: for spade rudder: M B =F R h s h s d s 1 -- M TR = k æ b ö è f 1 ø (knm) (mm) F R H M B = (knm) 7 for semi-spade rudder: M B F R H = (knm) 17 = vertical distance in m from the centroid of the rudder area to the middle of the neck bearing or the coupling. At the bearing above neck bearing M B = 0, except as follows: for rotary vane type actuators with two rotor bearings, which allow only small free deflections, calculation of bending moment influence may be required if bending deflection in way of upper bearing exceeds two times diametrical bearing clearances at full rudder force F R for actuator force induced bending moment the greater of the following: M BU =F A h A (knm) or M BU =P A h A (knm) h A =vertical distance between force and bearing centre P A =according to J0 M BU =bending moment at bearing above neck bearing. Minimum diameter of the rudder stock between the neck and the bearing above is not to be less than if tapered with k b =1,0 at the second bearing. 0 Tapered cone connections between rudder stock and rudder and steering gear are to have strength equivalent to that required for rudder stock with respect to transmission of torque and bending moments as relevant and are to comply with the following: a) Length/diameter ratio: Connection Rudder Steering gear l t /d s 1,5 0,75 b) Hub/shaft diameter ratio D/d s : c) Taper of cone: d) Contact surface roughness in micron: contact area minimum 70% evenly distributed (see K00 for control and testing) if oil is used for fitting, the design must enable escape of the oil from between the mating surfaces the connection is to be secured by a nut which is properly locked to the shaft. e) The dimensions at the slugging nut are not to be less than (see Fig. 10): external thread diameter: d g =0,65d s height of nut: h n =0,6d g outer diameter of nut: d n =1,d t or d n =1,5d g whichever is the greater. f) Average surface pressure p r due to shrinkage for transmission of torque by means of friction is to be: T fr 10 6 p r (N/mm ) πd m lµ T fr d m l = required torque to be transmitted by means of friction in following couplings: 1) Keyless rudder stock connections to: rudder: M TR steering gear: T des T fr M TR ) Keyed rudder stock connections to: rudder: 1,5 M TR (0,5 M TR ) steering gear: T fr T W (0,5 T W ) (figures in parentheses are subject to special consideration - see 0) = mean diameter = 0,5 (d s +d t )(mm) = effective cone length, which may normally be taken as boss length l t, see Fig. 10, (mm) mu = maximum 0,1 for oil injection fitting = maximum 0,17 for dry fitting M TR = rule rudder torque (knm), see D10 and D0 T des = maximum torque corresponding to steering gear design pressure, or safety valve opening pressure (knm) - see J0 for calculation of T des T w Type With key Keyless D/d s 1,5 1,5 Type With key Keyless taper 1:10-1:15 1: 15 Type of fitting Dry fitted Oil injection roughness (R A ) maximum,5 maximum 1,6 = effective steering gear torque at maximum working pressure (knm).

17 Rules for Ships, January 000 Pt. Ch. Sec. Page 17 g) The surface pressure (p) used for calculation of pull-up length is not to be taken less than: p r p min 1,5 p b (N/mm ) and is not to exceed: k = 0,95 for steel forging and cast steel = 0,90 for nodular cast iron = 0,50 for keyed connections. Variation due to different hub wall thickness is to be considered. Pressure at the bigger end due to bending moment, M b, may be taken as: which may be reduced to zero at a distance l x =0,5dor 0,5 l (smaller applies) as follows: p bx = pressure due to bending moment at position x l x = distance from top of cone, see Fig. 10 (mm) d x = ditto shaft diameter at distance l x (mm) M b = bending moment (knm). h) Shrinkage allowance (mm): E i = module of elasticity of shaft (N/mm ) E e = module of elasticity of hub (N/mm ) ν i = Poisson's ratio for shaft ν e = Poisson's ratio for hub c i c e = diameter ratio d i /d at considered section = diameter ratio d/d at considered section d i = diameter of centre bore in shaft (mm) d = shaft diameter at considered section (mm) D = outer diameter of the hub at considered section (mm). Minimum shrinkage allowance may be calculated based on average diameters and the surface pressure (p min ) from the above equation. However, in case hub wall thickness have large variations either longitudinally or circumferencially this equation is not valid. Maximum shrinkage allowance is to be calculated based on maximum permissible surface pressure (p max,seeg). i) Pull-up length, minimum: δ min =K( min +(R Ai +R Ae )10 - ) (mm) δ min mm for all keyless rudder - rudder stock connections. j) Pull-up length, maximum: δ max =K( max +(R Ai +R Ae )10 - )(mm) δ 1 c e p max kσ f p b (N/mm ) + c e p b, 5M b = d m l (N/mm ) æ l p bx p b18 1 x ö = ç è 05d, x ø = pull-up length (mm) (N/mm ) d p 1 c æ + e ö p ç v E e c æ + i ö = + ç v e è1 c ø E i i è e 1 c ø i K = taper of the cone = l t /(d s d t ) min = calculated minimum shrinkage allowance max =calculated maximum shrinkage allowance R Ai = surface roughness R A of shaft (micron) R Ae = surface roughness R A of hub (micron). k) Necessary force for pull-up may be estimated as follows: µ pu = average friction coefficient for pull-up (for oil injection (usually in the range 0,01 to 0,0). 0 Tapered key-fitted (keyed) connections are to be designed to transmit rudder torque in all normal operating conditions by means of friction in order to avoid mutual movements between rudder stock and hub. The key is to be regarded as a securing device. For calculation of minimum and maximum pull-up length see 0 i) and j). Where it is not possible or practicable to obtain above required minimum pull-up, special attention is to be given to fitting of the key in order to ensure tight fit (no free sideways play between key and key-way). Tapered key-fitted connections are in addition to comply with following: a) Key-ways shall not be placed in areas with high bending stresses in the rudder stock and are to be provided with sufficient fillet radii (r): r 0,01 d s b) The abutting surface area between the key and key-way in the rudder stock and hub respectively, is not to be less than: 65T key A ab (cm ) d m f k where the torque T key is (knm): 1,5 T des T fr T key M TR T fr based on verification of pull-up force, and 1,5 T des 0,7T fr T key M TR 0,7T fr based on verification of pull-up distance, but not less than: T key =M TR (knm). Yield strength used for calculation of f k is to exceed the lowest of: σ f,key and 1,5 σ f, hub (for calculation of hub) or 1,5 σ f, stock (for calculation of stock). A ab =effective abutting area of the key-way in stock and hub respectively (cm ) f k =material factor (see B0) σ f,hub =yield strength of hub material (N/mm ) σ f,key =yield strength of key material (N/mm ) σ f,stock =yield strength of stock material (N/mm ). c) The height/width ratio of the key is to be: h -- 0, 6 b h b F πd m lp æ 1 r µ ö èk pu 10 ø = height (thickness) of the key = width of the key. (kn)