Section 1 General requirements

1.1.1 A elevating wheel-house system generally consists of several concentrically mounted slidable columns with the wheel-house fitted on the top of the innermost column, see Figure 13.1.1 General sketch elevating wheel-house. The number of columns normally varies between 2 and 4. The columns are usually square or rectangular. The wheel-house can be moved up and down by means of one or more (hydraulic) lifting cylinder(s) to reach the desired height. Another configuration may consist of a wheel-house fitted on a scissor lift, see Figure 13.1.2 Scissor lift, or may consist of a wheel-house suspended by hydraulic jacks. This Chapter mainly deals with elevating wheel-house systems of the type with the slidable columns. Other systems will be specially considered.

Figure 13.1.1 General sketch elevating wheel-house

Figure 13.1.2 Scissor lift

1.1.2 The forces between the columns are transferred by support/sliding blocks, here after referred to as blocks.

1.1.3 The elevating wheel-house columns may be integrated into the ship's structure as follows:

1. The outer column is fully integrated with the (flexible mounted) deck-house, see Figure 13.1.3 Wheel-house configuration 1. In this case one or more pillars may need to be fitted underneath the outer column for additional vertical support. In cases where the deck-house is flexibly mounted on vibration mounts vibration mounts will also need to be fitted between the column and the additional pillar(s).

2. The outer column is integrated in the (flexibly mounted) deck-house and is continued up to the bottom construction of the ship, see Figure 13.1.4 Wheel-house configuration 2. In cases where the deck-house is flexibly mounted on vibration mounts the outer column will need to be mounted on vibration mounts in way of the bottom structure as well.

3. The outer column is independent of the flexibly mounted deck-house and directly fitted onto the bottom construction of the ship, see Figure 13.1.4 Wheel-house configuration 2. In this case the columns are fully integrated with the ship's structure and it may be desired to mount the wheel-house on vibration mounts at the connection with the top of the innermost column in order to isolate it from vibrations generated within the ship.

Figure 13.1.3 Wheel-house configuration 1

Figure 13.1.4 Wheel-house configuration 2

Figure 13.1.5 Wheel-house configuration 3

1.1.4 In the case of the elevating wheel-house being arranged with columns (see Figure 13.1.3 Wheel-house configuration 1), the bottom structure of the wheel-house should consist of 4 main girders fitted in line with the inner column plating and forming a cross of a pair of beams. The ends of the girders in way of the wheelhouse external walls can be considered as ‘free’ whilst the girders can be considered as ‘clamped’ in way of the inner column plating. The primary bottom structure should therefore be considered as being built of eight girders clamped at one side (at the inner column). See Figure 13.1.6 Primary floor girders.

Figure 13.1.6 Primary floor girders

1.2.1 Elevating wheel-house systems are to be made of steel or aluminium and are to be adequately supported. The materials used are to comply with the applicable requirements stated in the Rules for the Manufacture, Testing and Certification of Materials, July 2022.

1.2.2 The wheel-house is to be capable of supporting its own weight, including all equipment, and the maximum number of persons allowed in the wheel-house simultaneously. A noticeplate in way of the entrance of the wheel-house should be fitted stating the maximum number of persons allowed in the wheel-house. The total mass corresponding with the number of people allowed should also be indicated. These figures are to be designated by the manufacturer. A minimum average weight of 75 kg per person is to be taken into account. Further specific design loads are given in Table 13.1.1 Design loads on columns and wheel-house and Table 13.1.2 Design loads on wheel-house floor and roof.

1.2.3 The columns are to be capable of withstanding loads induced by heeling or rolling of the ship as well as loads induced by a collision.

1.2.4 The blocks are to be capable of transferring the loads transferred by the columns.

1.2.5 The hydraulic cylinder(s) is/are to be capable of supporting the wheel-house, the number of columns connected, and the specified number of persons in the wheelhouse, taking into account a dynamic factor of 1,20 on the static load.

1.2.6 The hydraulic cylinder(s) is/are to be of an approved type.

1.2.7 The cylinder support constructed in the bottom of the outer column is to be capable of withstanding the loads imposed by the hydraulic cylinder including its own weight and the dynamic factor mentioned in Pt 3, Ch 13, 1.2 General requirements 1.2.5.

1.2.8 Attention is drawn to Pt 5, Ch 18 Elevating Wheelhouse Systems regarding machinery aspects and Pt 6, Ch 1 Control Engineering Systems in respect of electrical and control engineering aspects.

1.2.9 When the proposed construction of the elevating wheel-house system differs from the general design as detailed in Pt 3, Ch 13, 1.1 General description 1.1.1, Pt 3, Ch 13, 1.1 General description 1.1.3 and Pt 3, Ch 13, 1.1 General description 1.1.4, it will be subject to special consideration.

1.2.10 The elevating wheel-house system is to be operated by the ship's crew only after complete installation and appropriate instructions by the manufacturer and final acceptance by Clasifications Register.

1.3.1 The design loads on the columns, blocks and cylinder support, if applicable, are given in Table 13.1.1 Design loads on columns and wheel-house. The design loads given in Table 13.1.1 Design loads on columns and wheel-house apply to ships navigating in Zone 3. For ships having the notation Zone 1 or Zone 2 in their Class Notation, the design loads are given in Pt 3, Ch 13, 1.7 Service in Zones 1 and 2 .

1.3.2 The design loads for the construction of the wheelhouse are given in Table 13.1.2 Design loads on wheel-house floor and roof and are applicable to ships navigating in all zones.

1.3.3 The design bending moment and shear forces of the main girder at the clamping in way of the column is to be determined as outlined in Table 13.1.3 Determination of bending moment and shear force in main girder of wheel-house foundation. Actual bending moments, shear forces and stresses may also be determined by direct calculations taking account of actual lengths and relative stiffnesses of the girders.

Table 13.1.3 Determination of bending moment and shear force in main girder of wheel-house foundation

Item	Parameter	Requirement
Maximum bending moment in main girder	BM
Maximum shear force in main girder	SF
Symbols
q 1 = q 2 = s 1 = spacing of main girder in way of clamping, in mm, see also Figure 13.1.9 Definition S 1 and S 2 s 2 = spacing of main girder at end, in mm, see also Figure 13.1.9 Definition S 1 and S 2 a = distance from inner column to wheel-house side plating, in metres b = distance from inner column to end of girder, in metres (= a in case of wheel-house without gallery) P = n = number of main girders (generally 8) p roof = as defined in Table 13.1.2 Design loads on wheel-house floor and roof, in kN/m2 Area roof = area of roof, in m2
Note For clarification, see also Figs. Figure 13.1.7 Load case elevating wheel-house, Figure 13.1.8 Load case elevating wheel-house with walkway and Figure 13.1.9 Definition S 1 and S 2 .

Figure 13.1.7 Load case elevating wheel-house

Figure 13.1.8 Load case elevating wheel-house with walkway

Figure 13.1.9 Definition S ₁ and S ₂

1.3.4 The column forces are the reaction forces resulting from the following:

• Loads due to the static heeling (Zone 3) or dynamic rolling (Zones 1 and 2 ) of the ship.
• Loads induced by a collision.
• Wind loads.

The method of calculation of these forces on the blocks is given in Table 13.1.4 Block force. Table 13.1.4 Block force is based on the assumption that the longitudinal and transverse centre of gravity of the system is approximately at the centre of the columns. If this is not the case the effects are to be taken account of by further direct calculations.

Table 13.1.4 Block force

Load	Requirement
Design horizontal load, F
Design bending moment, M
Upper block force R upper, per block
Lower block force R lower, per block
Symbols
A i = projected area of part i of the elevating wheel-house system, perpendicular to the wind direction, in m2 h wi = distance of the centre of area Ai up to upper block, in metres m i = mass of part i of the elevating wheel-house system, in ton h mi = distance of the centre of gravity of part i of the elevating wheel-house system up to upper block, in metres F roll,dyn,i = transverse component of dynamic roll, only applicable when sailing in Zone 1 or 2, see Pt 3, Ch 13, 1.7 Service in Zones 1 and 2 n = total number of parts of the elevating wheel-house system, including the wheel-house, excluding the column of the upper block under consideration and columns below, see also Note 1 p w = wind pressure, see Table 13.1.1 Design loads on columns and wheel-house ζ = sin φ for heeled or rolling conditions; = 0,50 for collisions φ = 10º for Zone 3, 15º for Zone 2, 20º for Zone 1, see also Pt 3, Ch 13, 1.7 Service in Zones 1 and 2 overlap = distance between lower blocks of a column and the upper blocks of the column below when the wheelhouse is in the outmost lifted position, see also Note 2
Note 1. See also Figs. Figure 13.1.10 Overview support/sliding blocks for an example of n = 4 Note 2. The required minimum overlap depends on the allowable forces. The following values could be used as a recommendation in the initial design stage: overlap ≈ 1 x maximum width of outer column for services in Zone 3, overlap ≈ 1,2 x maximum width of outer column for services in Zone 2, and overlap ≈ 11/2 x maximum width of outer column for services in Zone 1 for the determination of the overlap between the outer column and the lowest middle column.

Figure 13.1.10 Overview support/sliding blocks

Figure 13.1.11 Mass forces

Figure 13.1.12 Wind forces

1.4.1 Where the outer column is integrated in the deckhouse (building methods in accordance with Figure 13.1.3 Wheel-house configuration 1 and Figure 13.1.4 Wheel-house configuration 2) the upper blocks of the outer column are to be in line with the topdeck of the deck-house. Provisions are to be made for an efficient and adequate distribution of loads into this deck. A buckling analysis of the topdeck plating in way may be required. If necessary, anti-buckling strips are to be fitted. Preferrably, the side plating of the outer column is to be arranged in line with the beams and girders in the top and lower deck of the deck-house. Where deck girders and beams are not in line, brackets are to be fitted in line with the column side plating connecting the outer column with the beams and girders in the deck-house.

1.4.2 Where the outer column is independent from the flexibly mounted deck-house and directly fitted on to the single or double bottom construction of the ship, provision is to be made to support the outer column at a distance as large as possible above the top of the bottom structure but not less than 2,0 m. These supports, consisting of heavy beams efficiently connected to the ship's supporting structure, are to be provided in the horizontal transverse and longitudinal direction of the ship in order to provide additional transverse and longitudinal support. In this way the occurrence of high bending moments induced by the outer column on the bottom structure is to be prevented.

1.4.3 The number, type and position of vibration mounts or so called flexibles are dependent on the type of mount, the weight of the elevating wheel-house, the method of building in and the amount of weight of the deck-house that is supported by the outer column. The vibration mounts should be of an approved type and should be installed in accordance with the manufacturer's recommendations.

1.4.4 If the cylinder support in the bottom of the outer column consists of an I-shaped beam, anti tripping brackets are to be placed on the beam in way of the cylinder. Tripping brackets are also to be placed on the beam in line with the vibration mounts below.

1.4.5 Items such as safety pins, axles, brackets, etc. are to be designed for the loads imposed on them including the appropriate dynamic factors using the allowable stresses as provided in Table 13.1.8 Safety factors on yield or 0,2 per cent proof stress.

1.5.1 In this Section, only requirements for the construction of the bottom structure of the wheel-house are given. The construction of the side walls and roof is to be carried out in accordance with good shipbuilding practice in line with the Builder's procedures and standards.

1.5.2 The main girders are defined as primary members. Other beams and stiffeners are defined as secondary members.

1.5.3 The connection of the main girders to the inner column is to be such that these can be considered as clamped. Accordingly, the web of the main girder is to be in line with the plating of the inner column. (Double) continuous welding is required.

1.5.4 The effective plate width of the attached cover plating on the bottom side of the wheel-house foundation is to be determined in accordance withPt 3, Ch 3, 3 Structural idealisation, with the factor f to be divided by 2. The effective width of a plate attached to the main girder is then calculated as follows:

1.5.5 The number of holes in the main girders is to be kept to a minimum. Holes are not allowed in the main girder in way of the connection to the inner column. Generally, a minimum of 1,50 times the web depth of the main girder under consideration is required between the edge of a hole and the inner column.

1.5.6 Openings in beams are to have well rounded corners. The diameter or height of any opening should not exceed half the depth of the web of the beam. For rectangular openings, the length of the opening is limited to 65 per cent of the web height. The distance between openings should generally not exceed 75 per cent of the diameter or length of the opening

1.5.7 Where larger holes are proposed, these are subject to special consideration and reinforcements by means of double plates or flanges having increased properties are required to compensate the loss of material.

1.5.8 The wheel-house is to be capable of being closed gastight when installed on dry cargo ships carrying dangerous goods in large quantities or on tankers carrying dangerous goods. See Pt 4, Ch 1, 12 Additional requirements for ships carrying dangerous goods and Pt 4, Ch 4 General Requirements For Tankers Carrying Dangerous Liquids in Bulk respectively.

1.5.9 In case of a gallery or walkway partly or totally being fitted around the wheel-house, extra attention is to be paid to its supporting arrangement. It is to be ensured that the beams are in line with local beams or main girders fitted in the wheel-house and are well clamped without the presence of any hard spots.

1.5.10 The stresses in the main girders of the wheel-house foundation can be calculated as stated in Table 13.1.5 Stresses in main girders of wheel-house.

Table 13.1.5 Stresses in main girders of wheel-house

Item	Parameter	Requirement
Bending Stress	σb
Shear stress	τ
Symbols
BM = max bending moment acc. to Table 13.1.3 Determination of bending moment and shear force in main girder of wheel-house foundation SF = max shear force acc. to Table 13.1.3 Determination of bending moment and shear force in main girder of wheel-house foundation Z = section modulus of main girder under consideration, in cm3 AW = web area of main girder under consideration, in mm2

1.5.11 The stresses in the other beams can be calculated as stated in Table 13.1.6 Stresses in secondary members of wheel-house.

Table 13.1.6 Stresses in secondary members of wheel-house

Item	Parameter	Requirement
Bending stress	σbl
Shear stress	τ 1
Symbols
φZ = section modulus coefficient, to be taken as 0,1 for secondary members where the end fixity of both ends is considered to be partial; to be taken as 0,5 for cantilever beams (as for the beam in the gallery) φA = web area coefficient, to be taken as 0,5 for secondary members where the end fixity of both ends is considered to be partial; to be taken as 1 for cantilever beams (as for the beam in the gallery) p = p floor or p walk as applicable as defined in Table 13.1.2 Design loads on wheel-house floor and roof s = stiffener spacing, in mm l = length of stiffener, in metres Z = section modulus of stiffener, in cm3 A W = web area of stiffener, in mm2

1.5.12 The stresses as calculated in Table 13.1.5 Stresses in main girders of wheel-houseand Table 13.1.6 Stresses in secondary members of wheel-house are to be lower than the allowable stresses as given in Pt 3, Ch 13, 1.8 Allowable stresses.

1.6.1 The thickness of the column plating is to be determined for each column. Parameters are the reaction forces in the blocks and the design bending moment in the columns. The thickness of the plating of the outer column is to be equal to the thickness of the lowest middle column (or inner column in the case of the total number of columns is 2). The minimum thickness, t _p is to be taken as the greater of t _p1 and t _p2:

where

t p	=	plating thickness of column under consideration, in mm, to be ≥ 8 mm for steel plating and ≥ 8 mm for aluminium alloys
k	=	material factor
σ0	=	yield stress of the used plating material or the 0,2 per cent proof stress (in the welded condition), in N/mm2
fos	=	factor of safety with respect to buckling aspects; to be taken as 1,2 for normal (rolling) conditions and 1,0 for collision condition
f block	=	reaction force in upper block of the column below, in tonf, = R upper as calculated in accordance with Table 13.1.4 Block force and, if applicable, Table Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2 , either in transverse or longitudinal direction
E	=	modulus of elasticity of material, in N/mm2
b c1	=	breadth of column under consideration, in mm, measured in the direction of F block
b c2	=	breadth of column under consideration, in mm, measured perpendicular to the direction of F block
M	=	design bending moment, in tonfm, as calculated in accordance. with Table 13.1.4 Block force and, if applicable, Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2
sf	=	safety factor for axial stresses, see Table 13.1.8 Safety factors on yield or 0,2 per cent proof stress.

Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2

Item	Requirement
Wind pressure, p w	0,038 tonf/m2
Roll period, T r	to be taken as 6 if GM is unknown
Transverse component of static roll, F roll, static, i, of the part i of the elevating wheel-house system, see also Note 1	ζ mi, tonf
Transverse component of dynamic roll, F roll, dyn, i, of the 0,07024 mi zi, tonf part i of the elevating wheel-house system, see also Note 2	0,07024 mi
Symbols
m I = mass of the part i of the elevating wheel-house system, in tonf z I = distance (perpendicular to deck) of centre of gravity of the part i to ship's centre of gravity, metres ζ = sinφ φ = max roll angle of the ship, in degrees, to be taken as: For Zone 1 service: 20º if the actual heeling angle is unknown For Zone 2 service: 15º if the actual heeling angle is unknown B = breadth of ship, in metres GM = metacentre height of ship, in metres
Note 1. The F roll, static, i is the mass component in the determination of F and M in Table 13.1.4 Block force. Note 2. The F roll, dyn, i is the dynamic component in the determination of F and M in Table 13.1.4 Block force. Note 3. Due to the different ship's sailing conditions, the rolling conditions may differ for each individual sailing condition. Therefore the transverse forces on the columns are at least to be calculated for the two main sailing conditions, i.e. the full load condition and the ballast condition. Note 4. Zones 1, 2, and 3 are defined in Pt 1, Ch 2, 2.2 Character symbols 2.2.1.

1.6.2 Where the proposed thickness is not in accordance to the required thickness, a double plate may be fitted in line with the blocks to assure sufficient strength against buckling. The double plate should be such that the least moment of inertia of the two plates together, l _comb, has a minimum value of:

taking into account an effective breadth of the column plating itself equal to the value of b _c1.

1.6.3 Generally, when a double plate is proposed, the dimensions b x t are to be as follows:

1.6.4 In view of potentionally high block forces the strength and means of attachment of the column plating in way of the blocks is to be specially considered and details of the blocks and plating in way are to be submitted for consideration.

1.7.1 Elevating wheel-houses on ships intended to navigate in Zones 1 or 2 are to withstand both the normal loads, as calculated in accordance with Table 13.1.4 Block force, as well as the forces induced by rolling of the ship when sailing under increased conditions as for Zones 1 and 2. In this case the additional loads are to be calculated in accordance with Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2 . The formulas in Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2 should be applied to each individual component of the elevating wheel-house system. The total bending moment acting on the outer column and the resulting reaction forces of the blocks are to be calculated as outlined in Table 13.1.4 Block force. The allowable stresses are to be determined according to Pt 3, Ch 13, 1.8 Allowable stresses.

1.7.2 The Builder of the elevating wheel-house system is to be provided with proper values of the hydrodynamic and hydrostatic parameters B, GM, and f.

1.7.3 When T _r and f are known through ship measurements or detailed analysis, these values are to be used in the calculation of Table 13.1.7 Determination of transverse forces of each individual componet of the elevating wheel-house system in Zones 1 and 2 .

1.8.1 The safety factors listed in Table 13.1.8 Safety factors on yield or 0,2 per cent proof stress are the limiting stress coefficients to be multiplied with the yield stress or the 0,2 per cent proof stress of the material as applicable. Thus the allowable stress = safety factor x σ_o , with σ_o as defined in Pt 3, Ch 13, 1.6 Columns.

1.8.2 In the determination of the magnitude of the equivalent stress, σ _eq, it is assumed that the stresses are combined using the following formula:

1.9.1 (Double) continuous welding is to be adopted in the following locations and may be used elsewhere if desired:

1. Primary and secondary members to plating in way of end connections.

2. Face flats to webs of built-up/fabricated stiffening members in way of knees/end brackets.

3. The cylinder supporting structure in the bottom of the outer column to the column plating.

4. The connection of the main girders of the wheel-house foundation to the side plating of the inner column.

5. Double plate on middle column if needed to fulfill buckling requirements.

6. Double plate on cylinder support if needed to fulfill shear strength requirements.

7. Anti-tripping brackets where high local loadings are imposed.

1.9.2 The throat thickness of the (double) continuous welds is to be 0,44 x t _p, with t _p being the least value of the plating thicknesses being joined. Full or deep penetration welding may be required where high local loadings are imposed.

1.10.1 The recommendations listed in this paragraph are non-Classification items and may be overruled or waived by different or additional requirements from the applicable National Authorities. It is however strongly recommended to implement these recommendations.

1.10.2 It is recommended to designate clearly and mark the area directly below the wheel-house as an area of non trespassing.

1.10.3 When the non trespass area as defined in Pt 3, Ch 13, 1.10 Non structurally related items 1.10.2 should be trespassed for maintenance purposes or for other reasons, it is recommended that the elevating wheel-house is secured from moving up or down.

1.10.4 External stairs for access to the wheel-house are not a classification item. It is however strongly recommended to indicate clearly the number of persons that are allowed simultaneously on the stairs and for which the stairs have been approved by the relevant authority.