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abschn14 | Bearing (Mechanical) | Propeller
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I - Part 1 GL 2011
Rudder and Manoeuvring Arrangement
Chapter 1 Page 14–1
Section 14 Rudder and Manoeuvring Arrangement
A. 1. General Manoeuvring arrangement ment and the lubricant from being washed away from the rudder carrier. If the top of the rudder trunk is below the deepest waterline two separate stuffing boxes are to be provided. Note The following measures are recommended in the GL Technical Publication, Paper No. 05-1 "Recommendations for Preventive Measures to Avoid or Minimize Rudder Cavitation", regarding: Profile selection: – – Use the appropriate profile shape and thickness. Use profiles with a sufficiently small absolute value of pressure coefficient for moderate angles of attack (below 5°). The pressure distribution around the profile should be possibly smooth. The maximum thickness of such profiles is usually located at more than 35 % behind the leading edge. Use a large profile nose radius for rudders operating in propeller slips. Computational Fluid Dynamic (CFD) analysis for rudder considering the propeller and ship wake can be used.
1.1 Each ship is to be provided with a manoeuvring arrangement which will guarantee sufficient manoeuvring capability. 1.2 The manoeuvring arrangement includes all parts from the rudder and steering gear to the steering position necessary for steering the ship. 1.3 Rudder stock, rudder coupling, rudder bearings and the rudder body are dealt with in this Section. The steering gear is to comply with the GL Rules for Machinery Installation (I-1-2), Section 14. 1.4 The steering gear compartment shall be readily accessible and, as far as practicable, separated from the machinery space. (See also Chapter II/1, Reg. 29.13 of SOLAS 74.) Note Concerning the use of non-magnetisable material in the wheel house in way of a magnetic compass, the requirements of the national Administration concerned are to be observed. 1.5 2. For ice-strengthening see Section 15. Structural details
Rudder sole cavitation: Round out the leading edge curve at rudder sole. Propeller hub cavitation: Fit a nacelle (body of revolution) to the rudder at the level of the propeller hub. This nacelle functions as an extension of the propeller hub. Cavitation at surface irregularities: – – Grind and polish all welds. Avoid changes of profile shape. Often rudders are built with local thickenings (bubbles) and dents to ease fitting of the rudder shaft. Maximum changes in profile shape should be kept to less than two percent of profile thickness.
2.1 Effective means are to be provided for supporting the weight of the rudder body 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. 2.2 Suitable arrangements are to be provided to prevent the rudder from lifting. Connections of rudder blade structure with solid parts in forged or cast steel, which are used as rudder stock housing, are to be suitably designed to avoid any excessive stress concentration at these areas. 2.3 The rudder stock is to be carried through the hull either enclosed in a watertight trunk, or glands are to be fitted above the deepest load waterline, to prevent water from entering the steering gear compart-
Gap cavitation: – – – Round out all edges of the part around the gap. Gap size should be as small as possible. Place gaps outside of the propeller slipstream.
see Rules II – Materials and Welding.Chapter 1 Page 14–2 Section 14 A Rudder and Manoeuvring Arrangement I . are applicable for normal strength hull structural steel.0 in general = 0.0 for NACA-profiles and plate rudder = 0. Part 1 – Metallic Materials. higher values may be used which will be fixed in each individual case.3 Before significant reductions in rudder stock diameter due to the application of steels with ReH exceeding 235 N/mm2 are accepted. Where more than one rudder is arranged the area of each rudder can be reduced by 20 %. 5.9 for bulk carriers and tankers having a displacement of more than 50 000 t = 1.75 for R eH > 235 [N / mm ] 2 Fig. The requirements of this Section are based on a material's minimum nominal upper yield point ReH of 235 N/mm2. 14.0 in general = 0. 4. Size of rudder area In order to achieve sufficient manoeuvring capability the size of the movable rudder area A is recommended to be not less than obtained from the following formula: = 235 R eH for R eH ≤ 235 [N / mm 2 ] ReH = minimum nominal upper yield point of material used [N/mm2] ReH is not to be taken greater than 0.35 times the projected area of the nozzle.2 In general materials having a minimum nominal upper yield point ReH of less than 200 N/mm2 and a minimum tensile strength of less than 400 N/mm2 or more than 900 N/mm2 shall not be used for rudder stocks. c4 = factor for the rudder arrangement: = 1. whichever is less.4 The permissible stresses given in E. Special material requirements are to be observed for the ice class notations E3 and E4 as well as for the ice class notations PC7 – PC1. Estimating the rudder area A B. 4.7 for tugs and trawlers c2 = factor for the rudder type: = 1.1 For materials for rudder stock. 14. Large deflections should be avoided in order to avoid excessive edge pressures in way of bearings. Materials At Af b c = A + area of a rudder horn. is to be observed. GL may require the evaluation of the elastic rudder stock deflections. If material is used having a ReH differing from 235 N/mm2.5 for rudders outside the propeller jet For semi-spade rudders 50 % of the projected area of the rudder horn may be included into the rudder area A.1 x2 c 4. Rm = tensile strength of the material used. 4.1. if any [m2] = portion of rudder area located ahead of the rudder stock axis [m2] = mean height of rudder area [m] = mean breadth of rudder area [m].9 for semi-spade rudders = 0. pintles. 4. A is not to be taken less than 1.0 for rudders in the propeller jet = 1.8 for hollow profiles and mixed profiles CR QR A = rudder force [N] = rudder torque [Nm] = total movable area of the rudder [m2]. coupling bolts etc. keys and bolts.7 · Rm or 450 N/mm2. see Fig. When higher tensile steels are used. measured at the mid-plane of the rudder For nozzle rudders. pintles.1 Rudder area geometry b . the material factor kr is to be determined as follows: A Af x1 c= x1 + x2 2 b= A c kr ⎛ 235 ⎞ = ⎜ ⎟ ⎝ R eH ⎠ 0. 75 ⋅ L ⋅ T [m 2 ] 100 = factor for the ship type: = 1. Definitions A = c1 ⋅ c2 ⋅ c3 ⋅ c 4 c1 1.7 for high lift rudders c3 = factor for the rudder profile: = 1.1.Part 1 GL 2011 3.
B. depending on the location of the rudder = 0.21 1.35 astern 1.4 ⋅ v0 or 6 kn.15 for rudders aft of the propeller nozzle κ3 = 0.75 for ahead condition for astern condition (general) for astern condition (hollow profiles) 1. if the astern speed va is less than 0.4 to be specially considered. 0) For ships strengthened for navigation in ice Section 15. If not known.7 κt = coefficient depending on the thrust coefficient CTh = 1. If no limitations for the rudder angle at astern condition is stipulated.2.0 normally k In special cases for thrust coefficients CTh > 1.1 1. including also rudders within the propeller jet = 1.2 The rudder torque is to be determined by the following formula: B.5.1 for astern condition.Part 1 GL 2011 Section 14 B Rudder and Manoeuvring Arrangement Chapter 1 Page 14–3 Λ = aspect ratio of rudder area At = b2 At Table 14. if not known: 1.0 determination of κt according to the following formula may be required: κt = C R (CTh ) CR (CTh = 1.7 Profile / type of rudder NACA-00 series Göttingen profiles flat side profiles mixed profiles (e. HSVA) hollow profiles v0 = ahead speed of ship [kn] as defined in Section 1. 1.25 = 0.9 is to be observed.1 The rudder force is to be determined according to the following formula: C R = 132 ⋅ A ⋅ v ⋅ κ1 ⋅ κ 2 ⋅ κ3 ⋅ κ t v κ1 = v0 = va for ahead condition for astern condition 2 [N] For parts of a rudder behind a fixed structure such as a rudder horn: α = 0.3 Effects of the provided type of rudder/profile on choice and operation of the steering gear are to be observed. g.55 for ahead condition for astern condition = coefficient.0 elsewhere. α = 0.1 = coefficient. B. For greater astern speeds special evaluation of rudder force and torque as a function of the rudder angle may be required. whichever is less. depending on the aspect ratio Λ = (Λ + 2)/3.33 = 0..1 ⋅ c [m] for ahead condition 1. Rudder Force and Torque Rudder force and torque for normal rudders r α Q R = C R ⋅ r [Nm] = c (α − k b ) [m] = 0.4 1. depending on the type of the rudder and the rudder profile according to Table 14.1 1. H.4 1. if this speed is less than 10 kn. 1. the factor κ2 is not to be taken less than given in Table 14. where Λ need not be taken greater than 2 For high lift rudders α is to be specially considered.40 may be used for the ahead condition kb = balance factor as follows: = Af A for unbalanced rudders κ2 = coefficient.4 1. .1 Coefficient κ2 κ2 ahead 1.I . determination of rudder force and torque for astern condition is not required.66 = 0. = material factor according to Section 2.08 rmin = 0. high lift rudders 1.8 for rudders outside the propeller jet = 1. v0 is to be taken as vmin = ( v0 + 20 ) 3 [kn] va = astern speed of ship [kn].
2.2 – B. 14.77 Dt and the height not less than 0. 1.1 The diameter of the rudder stock for transmitting the rudder torque is not to be less than: Dt = 4. The length of the edge of the quadrangle for the auxiliary tiller shall not be less than 0.3 In case of mechanical steering gear the diameter of the rudder stock in its upper part which is only intended for transmission of the torsional moment from the auxiliary steering gear may be 0.2 and B.3 The total rudder torque is to be determined according to the following formulae: QR Q R min r1. 14. 14. The degree of the permissible axial clearance depends on the construction of the steering engine and on the bearing. the stock diameter has to be suitably increased.2 The total rudder force CR is to be calculated 2.2. Scantlings of the Rudder Stock Rudder stock diameter c1 1. upon which the determination of rudder torque and rudder blade strength are to be based.3 The related torsional stress is: c2 Fig. 14. C. see Fig.2.1 according to 1.2min = = Q R1 + QR 2 = CR ⋅ r1.3 and under consideration of the frictional losses at the rudder bearings.2 c1 c2 = A1 b1 A = 2 b2 2. The pressure distribution over the rudder area.1. 2 3 QR ⋅ k r [mm] A2 A2f b2 QR = see B.1 If the rudder is so arranged that additional bending stresses occur in the rudder stock.2 Partial rudder areas A1 and A2 The resulting torque of each part may be 2.8 Dt.2.2 or B.2 The steering gear is to be determined according to the GL Rules for Machinery Installations (I-12).1 (c1 ⋅ A1 + c2 ⋅ A 2 ) [m] A for ahead condition The greater value is to be taken.2.4 The rudder stock is to be secured against axial sliding.Chapter 1 Page 14–4 Section 14 C Rudder and Manoeuvring Arrangement I . B. b2 = mean heights of the partial rudder areas A1 and A2.4.1. is to be derived as follows: The rudder area may be divided into two rectangular or trapezoidal parts with areas A1 and A2.2.Part 1 GL 2011 2. see Fig. b1 A1 A1f 1. Strengthening of rudder stock = c2 (α − k b2 ) [m] k b1 = k b2 = A1f.2 taken as: Q R1 = C R1 ⋅ r1 Q R2 = C R2 ⋅ r2 r1 r2 = c1 (α − k b1 ) A1f A1 A 2f A2 [Nm] [Nm] [m] τt kr = 68 kr [N / mm 2 ] = see A.1. 2.9 Dt. The increased . Section 14 for the rudder torque QR as required in B.2 min [Nm] [Nm] or 0. Rudder force and torque for rudder blades with cut-outs (semi-spade rudders) b1.2 1. A2f see Fig. The resulting force of each part may be taken as: A1 C R1 = CR A C R2 = CR A2 A [N] [N] 2. 1.
1.4) = unit displacement due to a torsional moment of the amount 1 ⋅ e [kNm] = d ⋅ e2 G ⋅ Jt The evaluation of bending moments.2. 14. 14.4): 4 ⎛ Mb ⎞ = 0. decisive for the scantlings of the coupling. CR2 see B.2 and B.2.3. d = distances [m] according to Fig. 3.1 = unit displacement of rudder horn [m] due to a unit force of 1 kN acting in the centre of support = 0. e. For the increased rudder stock diameter the equivalent stress of bending and torsion is not to exceed the following value: σv = σ2 b + 3τ 2 Load on rudder body (general): pR = 10 CR ⋅ 103 [kN / m] 118 ≤ kr Load on semi-spade rudders: [N / mm ] 2 p R10 = p R 20 = CR 2 10 Bending stress: σb Mb = 10.1.3): Z = 6.2. 3.1 Analysis General 50 for the support in the rudder horn (Fig. where applicable. Z = spring constant of support in the sole piece or rudder horn respectively Torsional stress: τ D1 = 5.3 – 14.2 10 = d ⋅ e2 ⋅ Σ ui ti 2 3.I . and I20 is the moment of inertia of the pintle in the sole piece.2 – B. and B. 21 d3 In [m / kN] (guidance value for steel) In ft = moment of inertia of rudder horn [cm4] around the x-axis at d/2 (see also Fig. shear forces and support forces for the system rudder .92 ⋅ 107 [kN/m2] for steel Data for the analysis – 40 = lengths of the individual girders of the system [m] Jt FT ui ti = torsional moment of inertia [m4] = mean sectional area of rudder horn [m2] = breadth [mm] of the individual plates forming the mean horn sectional area = plate thickness within the individual breadth ui [mm] I10 – I40 = moments of inertia of these girders [cm4] For rudders supported by a sole piece the length 20 is the distance between lower edge of rudder body and centre of sole piece. additional bending moments may be transmitted from the steering gear into the rudder stock. CR1.4 . 14. These additional bending moments are to be taken into account for determining the rudder stock diameter. 3.2 – 3.1 ⋅ D t 6 1 + ⎜ ⎟ 3 ⎝ QR ⎠ 2 Z fb = 1 fb + ft [kN / m] = see B.18 ⋅ I50 3 = increased rudder stock diameter [cm] [kN / m] The increased rudder stock diameter may be determined by the following formula: D1 QR Dt Note Where a double-piston steering gear is fitted. 14.1 ⋅ Q R 3 D1 [N / mm 2 ] for the support in the sole piece (Fig.3 = see 1.5 as outlined in 3. 2 ⋅ M b 3 D1 ⋅ 103 CR1 ⋅ 103 [kN / m] [kN / m] [N / mm 2 ] 20 = bending moment at the neck bearing [Nm] CR. 14.17 ⋅ 108 ⋅ FT [m / kN] for steel G = modulus of rigity = 7.rudder stock may be carried out for some basic rudder types as shown in Figs.Part 1 GL 2011 Section 14 C Rudder and Manoeuvring Arrangement Chapter 1 Page 14–5 diameter is.
14.Part 1 GL 2011 B3 I40 I30 Mb B2 40 10 30 I10 pR 20 I20 MR I50 Z B1 50 System M Q Fig.Chapter 1 Page 14–6 Section 14 C Rudder and Manoeuvring Arrangement I . 14.3 Rudder supported by sole piece B3 I40 I 30 I20 40 Mb B2 30 B1 pR20 Z Q1 I10 e 10 d 2 20 d pR10 System M Q Fig.4 Semi-spade rudder .
1 [N] + 10 (2 x1 + x 2 ) ⎞ ⎟ [Nm] 3 (x1 + x 2 ) ⎠ . B3 are to be evaluated.1. and C. C. 14.5 Spade rudder B3 30 Mb x3 A1 x2 MCR1 CR1 pR MR B2 Z= 10 20 10 A2 x1 System M Q Z=0 Fig.2 For spade rudders the moments and forces may be determined by the following formulae: ⎛ M b = CR ⎜ ⎝ 20 B3 B2 = Mb 30 [N] [N] = CR + B3 3.3 For spade rudders with rudder trunks (see Fig. the bending moment Mb in the neck bearing and the support forces B1. and E.5. 14.1 Q1 in the rudder body. The so evaluated moments and forces are to be used for the stress analyses required by 2. B2.3.3 Moments and forces to be evaluated The bending moment MR and the shear force 3. 3.6) the moments and forces may be determined by the following formulae: CR1 = rudder force over the partial rudder area A1 according to B.2.I .3.1 [N] CR2 = rudder force over the partial rudder area A2 according to B.Part 1 GL 2011 Section 14 C Rudder and Manoeuvring Arrangement Chapter 1 Page 14–7 B3 30 B2 20 x2 Mb 10 pR x1 System M Q Fig. of this Section and by Section 13.6 Spade rudders with rudder trunks inside the rudder body 3.2.4. 14.3.
A report is to be submitted to the Surveyor.1 In case the rudder trunk is welded directly into the skeg bottom or shell. Before welding is started. by a calculation acc. as given in B. subsequent heat treatment and inspections traceable to the welds. welding positions. For spade rudders of the high lift type. The bolts and nuts are to be effectively secured against loosening. the bending stress in the rudder trunk.4. hot spot stress has to be determined acc. The radius is to be checked with a template for accuracy. In horizontal couplings. D. Table 20. see Section 20.2 The weld at the connection between the rudder trunk and the shell or the bottom of the skeg is to be full penetration. to Section 20. and the rudder blade The fillet shoulder radius is to be ground.3 The minimum thickness of the shell or the bottom of the skeg is to be 0. 4. FAT class ΔσR for the case E 2 or E 3 acc.2.Part 1 GL 2011 MCR1 = CR1 ⋅ 20 ⎛ 2 x2 + x3 ⎞ ⎜1 − ⎟ [Nm] 3(x 2 + x 3 ) ⎠ ⎝ [Nm] [Nm] MCR2 = CR 2 ⋅ MR Mb B3 B2 4. 10 (2 x1 + x 2 ) 3 (x1 + x 2 ) 4. In this case FAT class ΔσR = 100 has to be used. In addition sufficient fatigue strength of the weld has to be verified e.3 The coupling bolts are to be fitted bolts.1 rudder trunk welded in such a way the rudder trunk is loaded by the pressure induced on the rudder blade.4 For spade rudders horizontal couplings according to 2. to Section 20. the span to be considered is the distance between the mid-height of the lower rudder stock bearing and the point where the trunk is clamped into the shell or the bottom of the skeg. to 4.4 times the wall thickness of the trunk at the connection.1. a detailed welding procedure specification is to be submitted to GL covering the weld preparation. In case of smaller wall thickness.2 In case the trunk is fitted with a weld flange. are permitted. The radius is to be as large as practicable but not less than 0. If disk grinding is carried out. 4. .3 has to be used. 1. The manufacturer is to maintain records of welding. welding consumables. Non destructive tests are to be conducted at least 24 hours after completion of the welding. Note The radius may be obtained by grinding.7. at least 2 bolts are to be arranged forward of the stock axis.7 times the wall thickness of the trunk at the connection. is to be in compliance with the following formula: σ ≤ 80 / k where the material factor k for the rudder trunk is not to be taken less than 0. 1. MCR2) = MCR2 – MCR1 = Mb 20 + [N] 30 = CR + B3 [N] Rudder trunk In case where the rudder stock is fitted with a 4. welding parameters.1. the radius shall be not less than 35 mm. preheating. 4. This welding procedure is to be supported by approval tests in accordance with the applicable requirements of materials and welding sections of the rules.2 times the diameter of the bolt. post weld heat treatment and inspection procedures. otherwise cone couplings according to 3.5 If a cone coupling is used between the rudder stock or pintle. Four profiles at least are to be checked.1. as the case can be. A.g. These records are to be submitted to the Surveyor. 1. in N/mm2. C. are to be applied.2 The distance of the bolt axis from the edges of the flange is not to be less than 1. Rudder Couplings General Non destructive tests are to be conducted for all welds.3. = Max (MCR1.6) can be carried out. 1. only cone couplings according to 3.1 The couplings are to be designed in such a way as to enable them to transmit the full torque of the rudder stock. the stresses have to be determined within the radius. 4. C. if the wall thickness is greater than 50 mm.4 Alternatively a fatigue strength calculation based on the structural stress (hot spot stress) (see Section 20. The welds are to be 100 % magnetic particle tested and 100 % ultrasonic tested. For the calculation of the bending stress.4. score marks are to be avoided in the direction of the weld.Chapter 1 Page 14–8 Section 14 D Rudder and Manoeuvring Arrangement I . 1. 1.4. are permissible only where the required thickness of the coupling flanges tf is less than 50 mm.
67 ⋅ db.2 The thickness of the coupling flanges clear of the bolt holes is not to be less than 0. 2. by a securing plate as shown in Fig. After ten applications or five years the blue print proof has to be renewed. the contact area between the mating surfaces is to be demonstrated to the Surveyor by blue print test and should not be less than 70 % of the theoretical contact area (100 %). e.3 The coupling flanges are to be equipped with a fitted key according to DIN 6885 or equivalent standard for relieving the bolts.9 ⋅ db kf = material factor for the coupling flanges analogue to A. which is not to be less than 6 = mean distance of the bolt axes from the centre of bolt system [mm] = material factor for the rudder stock as given in A.5 For the connection of the coupling flanges with the rudder body see also Section 19. The cone shapes should fit very exact. dg dn securing plate for nut Fig.65 ⋅ tf. [mm] = total number of bolts. Non-contact areas should be distributed widely over the theoretical contact area.7. B.2 The coupling length shall.5 ⋅ d0. in general.1 of 1 : 8 . 2. In case of storing over a longer period.4.4.4. sufficient preservation of the surfaces is to be provided for. 3. The proof has to be demonstrated using the original components and the assembling of the components has to be done in due time to the creation of blue print to ensure the quality of the surfaces. If alternatively a male/female calibre system is used. Horizontal couplings The fitted key may be dispensed with if the diameter of the bolts is increased by 10 %.2 The thickness of the coupling flanges is not to be less than determined by the following formulae: tf = 0. 2.4.1.2 = design yield moment of rudder stock [Nm] according to F.4. = diameter of the conical part of the rudder stock [mm] at the key ReH1 = minimum nominal upper yield point of the key material [N/mm2] d0 insulation liner sealing/ insulation da dm du hn 2.4.I .). Concentrated areas of non-contact in the forward regions of the cone are especially to be avoided. 62 D3 ⋅ k b kr ⋅ n ⋅ e [mm] as QF dk = 16 ⋅ Q F d k ⋅ R eH1 [cm 2 ] = rudder stock diameter according to C.1.4.4 Horizontal coupling flanges shall either be forged together with the rudder stock or be welded to the rudder stock as outlined in Section 19. 62 D3 ⋅ k f kr ⋅ n ⋅ e [mm] tfmin = 0.g. 14. 2. 3. 3.3. the shear area of which is not to be less than: 2.1 : 12.Part 1 GL 2011 Section 14 D Rudder and Manoeuvring Arrangement Chapter 1 Page 14–9 or steering gear (see 3. B. 14. c = (d0 – du)/ according to Fig.7 Cone coupling with key and securing plate .1 Cone couplings Cone couplings with key Cone couplings shall have a taper c on diameter 3. the contact area between the mating surfaces is to be checked by blue print test and should not be less than 80 % of the theoretical contact area (100 %) and needs to be certified.2 = material factor for the bolts analogue to A. The width of material outside the bolt holes is not to be less than 0.7. 3.1 The diameter of coupling bolts is not to be less than: db D n e kr kb = 0. The nut is to be carefully secured. not be less than 1. 14.1.3 For couplings between stock and rudder a key is to be provided.
2 Cone couplings with special arrangements for mounting and dismounting the couplings ReH = yield point [N/mm2] of the securing flat bar material 3. 3.1 Push-up pressure The push-up pressure is not to be less than the greater of the two following values: Where the stock diameter exceeds 200 mm 3. stock or coupling material [N/mm2].Part 1 GL 2011 3. In such cases the cone shall be more slender. whichever is less. see Fig.5 ⋅ dg external thread diameter: dg = 0. normally μ1 = 0.Chapter 1 Page 14–10 Section 14 D Rudder and Manoeuvring Arrangement I . see Fig.6 It is to be proved that 50 % of the design yield moment will be solely transmitted by friction in the cone couplings.2. 3.15 (frictional coefficient) Mb = bending moment in the cone coupling (e. in case of spade rudders) [Nm] Fig.1.2.8 Cone coupling without key and with securing flat bar It has to be proved that the push-up pressure does not exceed the permissible surface pressure in the cone.3 = mean diameter of the frictional area between nut and rudder body. 14.1.5 The dimensions of the slugging nut are to be at least as follows.3.65 ⋅ d0 Pe = ⎛d ⎞ Pe ⋅ μ1 ⎜ 1 − 0. A securing plate for securing the nut against the rudder body is not to be provided.3 for a torsional moment Q'F = 0.2. 3. [Nm] = mean cone diameter [mm] = cone length [mm] μ0 Securing flat bar dg d1 ≈ 0.8. The permissible surface pressure is to be determined by the following formula: .2.3. 3.6 ⋅ dg outer diameter (the greater value to be taken): dn = 1.2.7: As Ps = Ps ⋅ 3 ReH [ mm 2 ] = shear force as follows – – – height: hn = 0. 14.g. p req1 = 2 ⋅ QF ⋅ 103 d2 ⋅ m ⋅ π ⋅ μ0 [N / mm 2 ] p req2 = QF dm 6 ⋅ M b ⋅ 103 2 ⋅ dm [N / mm 2 ] = design yield moment of rudder stock according to F.3 For the safe transmission of the torsional moment by the coupling between rudder stock and rudder body the push-up length and the push-up pressure are to be determined by the following formulae.2 In case of hydraulic pressure connections the nut is to be effectively secured against the rudder stock or the pintle. c ≈ 1 : 12 to ≈ 1 : 20.2 ⋅ du or dn = 1.2 [N] = frictional coefficient between nut and rudder body.6 ⎟ ⎜ dg ⎟ 2 ⎝ ⎠ [N] = push-up force according to 3. 14.2.8 = thread diameter of the nut μ1 d1 dg 3. This can be done by calculating the required push-up pressure and push-up length according to 3.1.5 ⋅ QF. see Fig. if its shear area is not less than: ak = 5 ⋅ QF d k ⋅ R eH2 [cm 2 ] ReH2 = minimum nominal upper yield point of the key.1 the press fit is recommended to be effected by a hydraulic pressure connection. 14.4 The effective surface area of the key (without rounded edges) between key and rudder stock or cone coupling is not to be less than: Note A securing flat bar will be regarded as an effective securing device of the nut.
where ho = height of opening. It varies and depends on the mechanical treatment and roughness of the details to be fixed. 1.8 ⋅ R tm c [mm] Note In case of hydraulic pressure connections the required push-up force Pe for the cone may be determined by the following formula: bending stress due to MR: σb = 90 N / mm 2 Pe = preq ⋅ d m ⋅ π ⋅ ⎛c ⎞ ⎜ + 0.15 ⋅ ho.2. In case of openings in the rudder plating for access to cone coupling or pintle nut the permissible stresses according to 1.8 ⋅ R eH (1 − α 2 ) 3 + α4 E.3 For rudder bodies without cut-outs the permissible stress are limited to: The outer diameter of the gudgeon shall not be less than: da = 1.9 .3. however. not to be taken greater than: Δ 2 = 1.Part 1 GL 2011 Section 14 E Rudder and Manoeuvring Arrangement Chapter 1 Page 14–11 p perm = 0.3 and 14.3.4.2.5 ⋅ d m [mm] 3. 14.4 apply.4 In rudder bodies with cut-outs (semi-spade rudders) the following stress values are not to be exceeded: The push-up length is.3 = pintle diameter [mm] according to Fig.7) The rudder body is to be stiffened by hori1.3 and Fig. see also Fig.06 ⋅ 105 N/mm2) equivalent stress due to bending and shear: σv = 2 σb + 3τ2 = 120 N / mm 2 MR. 4 B1 dm. Smaller permissible stress values may be required if the corner radii are less than 0.4 The required push-up pressure for pintle bearings is to be determined by the following formula: shear stress due to Q1: τ = 50 N / mm 2 torsional stress due to Mt: τt = 50 N / mm 2 equivalent stress due to bending and shear and equivalent stress due to bending and torsion: σ v1 = σ v2 = σ2 + 3τ 2 = 120 N / mm 2 b 2 σb + 3τ t2 = 100 N / mm 2 p req = 0.4 = see 3. 14. Q1 see C.6 ⋅ R eH ⋅ d m 3 + α4 E ⋅ c + 0.3. The rudder shall be additionally stiffened at the aft edge.2.2 The strength of the rudder body is to be proved by direct calculation according to C.2. f2 = see Fig.01 mm c E = taper on diameter according to 3. 1. this may be taken into account when fixing the required pushup length.2 Push-up length The push-up length is not to be less than: bending stress due to MR: Δ1 = preq ⋅ dm 0. subject to approval by GL. Rudder Body. 1.02 ⎟ [N] ⎝2 ⎠ The value 0.1 zontal and vertical webs in such a manner that the rudder body will be effective as a beam. 14.I .7 M R = CR2 ⋅ f1 + B1 Q1 = CR2 [N] f2 2 [Nm] f1. 1.8 ⋅ R tm + 2⎞ c ⎛1 − α E⎜ c ⎜ 2 ⎟ ⎟ ⎝ ⎠ [mm] σb τ = 110 N / mm 2 shear stress due to Q1: = 50 N / mm 2 Rtm = mean roughness [mm] ≈ 0. 3. Where due to the fitting procedure a partial push-up effect caused by the rudder weight is given. d0 B1 ⋅ d0 d2 ⋅ m [N / mm 2 ] = supporting force in the pintle bearing [N]. Rudder Bearings Strength of rudder body ReH = yield point [N/mm2] of the material of the gudgeon α = dm da (see Fig. 14.02 is a reference for the friction coefficient using oil pressure. 14.1 = Young's modulus (2.
1. Their minimum thickness is tmin = 8 mm for metallic materials and synthetic material 2. 2. 3.2 For connecting the side plating of the rudder to the webs tenon welding is not to be used. A. 14.1.2 ⋅ h.3.3 The thickness of the webs is not to be less than 70 % of the thickness of the rudder plating according to 2. Rudder plating For transmitting the rudder torque.6 Dt. As a first approximation the bearing force may be determined without taking account of the elastic supports. the latter shall have the diameter Dt or D1. but in no case less than 50 mm.2 t pR a = 1. The centre of pressure is to be assumed at 0. Where application of fillet welding is not practicable.8.3 for shell structures applies analogously. see Fig.1 has to be observed in addition. in spade rudders to 0. A sufficient number of vertical webs is to be fitted in way of the coupling. The thickness shall. This can be done as follows: The influence of the aspect ratio of the plate panels may be taken into account as given in Section 3. 10 ⋅ A = the smaller unsupported width of a plate panel [m] 4. the rudder stock is to be suitably increased in diameter in way of bearings enabling the stock to be re-machined later.9.3. 3. Downwards it may be tapered to 0.1 The thickness of the rudder plating is to be determined according to the following formula: = 22 mm for lignum material Where in case of small ships bushes are not fitted.Chapter 1 Page 14–12 Section 14 E Rudder and Manoeuvring Arrangement I .4. 4.2 If the torque is transmitted by a prolonged shaft extended into the rudder.9 Geometry of a semi-spade rudder 2. the side plating is to be connected by means of slot welding to flat bars which are welded to the webs. t = [cm]. if sufficient support is provided for. A.Part 1 GL 2011 A-B 2 2 a To avoid resonant vibration of single plate fields the frequency criterion as defined in Section 12. . 4.1 fitted. however.1.1 is to be increased by 25 % in way of the coupling. where c2 = mean breadth of area A2).4 times the strengthened diameter. 14. 74 ⋅ a 3 pR ⋅ k + 2.1 plating according to 2. see Fig. 2. B.3 The bearing forces result from the direct calculation mentioned in C. h. Rudder bearings In way of bearings liners and bushes are to be 4. – normal rudder with two supports: The rudder force CR is to be distributed to the supports according to their vertical distances from the centre of gravity of the rudder area. at the upper 10 % of the intersection length. B. whichever is greater. The radii in the rudder plating are not to be less than 4 – 5 times the plate thickness. 14. the rudder 3. r f2 f1 r t a A a A2 e B h x x a Fig. but not less than: The torsional stress may be calculated in a simplified manner as follows: τt Mt = Mt [N / mm 2 ] 2 ⋅ ⋅ h ⋅ t t min = 8 k [mm] Webs exposed to seawater shall be dimensioned according to 2.4. Regarding dimensions and welding Section 19. Transmitting of the rudder torque = CR2 ⋅ e [Nm] CR2 = partial rudder force [N] of the partial rudder area A2 below the cross section under consideration e = lever for torsional moment [m] (horizontal distance between the centre of pressure of area A2 and the centre line a-a of the effective cross sectional area under consideration.9 The distance between the vertical webs shall not exceed 1.5 [mm] CR [kN / m 2 ] = 10 ⋅ T + An adequate lubrication is to be provided. .33 ⋅ c2 aft of the forward edge of area A2.3. not be less than the thickness tmin according to Section 6.
bronze and hot-pressed bronze-graphite materials 1 5. Guidance values for bearing clearances 6. they are to comply with the following Ab = B q B [mm 2 ] q taper on diameter taper on diameter = support force [N] = permissible surface pressure acc. Surface pressures exceeding 5. Design Yield Moment of Rudder Stock The design yield moment of the rudder stock is to be determined by the following formula: Q F = 0.6 The bearing height shall be equal to the bearing diameter.5 and 3. .5 N/mm 2 may be accepted in accordance with bearing manufacturer's specification and tests. Stainless and wear resistant steel in an approved combination with stock liner. Pintles 6. 13. bronze and hot-pressed bronze-graphit materials have a considerable difference in potential to non-alloyed steel.0 1 : 8 to 1 : 12 if keyed by slugging nut 1 : 12 to 1 : 20 if mounted with oil injection and hydraulic nut Table 14. 4.1 the conditions given in 4. Higher surface pressures than 7 N/mm 2 may be accepted if verified by tests.2 times the bearing diameter.5 in Section 13.Part 1 GL 2011 Section 14 F Rudder and Manoeuvring Arrangement Chapter 1 Page 14–13 – semi-spade rudders: – support force in the rudder horn: B1 = CR ⋅ b c [N] d = B1 kr 0.3.1 For metallic bearing material the bearing clearance shall generally not be less than: Synthetic materials to be of approved type.2 Bearing material lignum vitae white metal. 6.4 and 4.I . 4. 5. 6. F.2. For nuts and threads the requirements of D. Respective preventive measures are required. the diameter Dta is to be used.5 7. is not to exceed 1.6.1.4 The pintles are to be arranged in such a manner as to prevent unintentional loosening and falling out. but in no case more than 10 N/mm 2. In case of self lubricating bushes going down below this value can be agreed to on the basis of the manufacturer's specification.3 The clearance is not to be taken less than 1.5 Stainless and wear resistant steels.5 mm on diameter. db + 1. 02664 Dt D3 t kr [Nm] = stock diameter [mm] according to C.5 4. 0 [mm] 1000 db = inner diameter of bush 2 4.1. Dta need not be taken greater than 1.3 Where pintles are of conical shape.2 If non-metallic bearing material is applied. Where the bearing depth is less than the bearing diameter.1 respectively. however.35 B1 ⋅ k r [mm] = support force [N] = see A.2 Permissible surface pressure q q [N/mm2] 2.2 The thickness of any liner or bush shall not be less than: For b and c see Fig.5 5.2 apply accordingly. oil lubricated synthetic material 1 steel 2. the bearing clearance is to be specially determined considering the material's swelling and thermal expansion properties.4.7 The wall thickness of pintle bearings in sole piece and rudder horn shall be approximately ¼ of the pintle diameter. The pintle diameter is not to be less than: Where the actual diameter Dta is greater than the calculated diameter Dt.145 ⋅ Dt. to Table 14. 5. However.2 – support force in the neck bearing: B2 = CR − B1 [N] 5. higher specific surface pressures may be allowed. 4. Pintles are to have scantlings complying with 5. 01 B1 [mm] or the values in 4.4 The projected bearing surface Ab (bearing height × external diameter of liner) is not to be less than t = 0.
35 see Fig.5 mm a = spacing of ring stiffeners [m] The following requirements are applicable to 1.10 b N Ap The motions of quadrants or tillers are to be limited on either side by stoppers. 3.7 for fixed nozzles = maximum shaft power [kW] = propeller disc area 2 [m2] D ε π = D 4 = propeller diameter [m] = factor according to the following formula: 5. 21 − 2 ⋅ 10−4 εmin = 0. This device as well as the foundation in the ship's hull are to be of strong construction so that the yield point of the applied materials is not exceeded at the design yield moment of the rudder stock as specified in F. however. The stoppers and their foundations connected to the ship's hull are to be of strong construction so that the yield point of the applied materials is not exceeded at the design yield moment of the rudder stock. Locking Device Stopper ε = 0. Nozzles with larger diameters will be specially considered. b/4 zone 2 zone 1 Fig. Where the ship's speed exceeds 12 kn. 1.2 The web thickness of the internal stiffening rings shall not be less than the nozzle plating for zone 3. zone 4 zone 3 min. 3. the design yield moment need only be calculated for a stock diameter based on a speed v0 = 12 kn. .Chapter 1 Page 14–14 Section 14 H Rudder and Manoeuvring Arrangement I . 14. 2. 14.0 = 0. Plug welding is only permissible for the outer nozzle plating. Propeller Nozzles General t = 5 ⋅ a pd + t K [mm] t min = 7. in no case be less than 7. 4. 14. Stopper.2 Special attention is to be given to the support of fixed nozzles at the hull structure.10 around its neutral axis is not to be less than: 2 W = n ⋅ d 2 ⋅ b ⋅ v0 [cm3 ] d b n = inner diameter of nozzle [m] = length of nozzle [m] = 1. Regarding stopper and locking device see also the GL Rules for Machinery Installations (I-1-2). 1. 2. Section 14.0 for rudder nozzles = 0.10 c = 1. Welding The inner and outer nozzle shell plating is to be welded to the internal stiffening rings as far as practicable by double continuous welds.1 propeller nozzles having an inner diameter of up to 5 m.5 = 0. Section modulus The design pressure for propeller nozzles is to be determined by the following formula: pd = c ⋅ pd0 [kN / m 2 ] pd0 = ε N Ap N Ap [kN / m 2 ] The section modulus of the cross section shown in Fig.5 mm. 1. Locking device in zone 2 (propeller zone) in zones 1 and 3 in zone 4 Each steering gear is to be provided with a locking device in order to keep the rudder fixed at any position. Design pressure 3.Part 1 GL 2011 G.1 The thickness of the nozzle shell plating is not to be less than: H.10 Zones 1 to 4 of a propeller nozzle Plate thickness 3.
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