Section 9 Bulwarks, guard rails, raised walkways and other means for the protection of crew and embarked personnel

9.1.1 Bulwarks or guard rails are to be provided at the boundaries of exposed decks. Bulwarks or guard rails are to be not less than 1,0 m in height measured above sheathing, and are to be constructed as required by this Section. Consideration will be given to cases where this height would interfere with the normal operation of the ship. Guard rails provided around aircraft operating areas may be of the type which drop outwards with nets which are to comply with Vol 1, Pt 3, Ch 4, 9.6 Safety nets. Droppable guard rails must be capable of being secured in both the upright and lowered position. Where bulwarks or guard rails are undesirable, e.g. for radar signature purposes, alternative equivalent arrangements will be required. Guidance on radar signatures is provided in Vol 1, Pt 4, Ch 1, 4.1 Radar signature.

9.1.2 The freeing arrangements in bulwarks are to be in accordance with Vol 1, Pt 3, Ch 4, 9.3 Freeing arrangements .

9.1.3 Guard rails fitted on superstructure and exposed decks are to have at least three courses. The opening below the lowest course of guard-rails is not to exceed 230 mm. The other courses are to be spaced not more than 380 mm apart. In the case of ships with rounded gunwales, the guard-rail supports are to be placed on the flat of the deck. In other locations, guard rails with at least two courses are to be fitted.

9.1.4 Guard rails are to be fitted with fixed, removable or hinged stanchions fitted no more than 1,5 m apart. Removable or hinged stanchions shall be capable of being locked in the upright position. When retracted, collapsed or removed, the guard rails are not to impede access/egress. Stowage is to be provided for portable stanchions and stays, sited adjacent to where they are to be used.

9.1.5 At least every third stanchion is to be supported by a stay.

9.1.6 Where necessary for the normal operation of the ship, steel wire ropes may be accepted in lieu of guard rails. Wires are to be made taut by means of turnbuckles. Chains are only permitted in short lengths in way of access openings.

9.1.7 Satisfactory means for safe passage of personnel, in the form of guard rails, life-lines, handrails, gangways, underdeck passageways or other equivalent arrangements, are to be provided for the protection of the crew and embarked personnel in getting to and from their quarters, the machinery space and all other spaces used in the operation of the ship.

9.1.8 A well illuminated and ventilated underdeck passage (with a clear opening at least 0,8 m in width and 2 m in height) is to be provided as close as practicable to the weatherdeck, connecting and providing access to the following locations:

• between superstructures;
• from the forwardmost superstructure to the forward end of the vessel;
• from the aftmost superstructure to the aft end of the vessel.

9.1.9 A means of passage over obstructions such as pipes or other fittings of a permanent nature is to be provided where practicable.

9.1.10 To assist movement in adverse weather conditions, handrails are to be fitted to bulkheads in passageways and superstructure on weatherdecks.

9.1.11 Handrails are to be fitted at a height of not less than 1 m, measured from the top of the rail to the deck. Handrails should be made of steel tubes of 42,4 mm outside diameter, with a wall thickness of at least 2,6 mm.

9.1.12 Handrails are to be secured by way of supports that are not to be spaced more than 1,5 m apart. The supports are to hold the rails not less than 50 mm from the bulkhead, measured from the inside of the rail to the bulkhead.

9.1.13 Raised walkways which form escape routes or assembly areas, or provide for the transfer of heavy equipment, stores or munitions, are to comply with the requirements of Vol 1, Pt 3, Ch 4, 9.5 Walkways.

9.1.14 For additional requirements for the safety of embarked persons, see Vol 3, Pt 2, Ch 6, 2.4 Safety of embarked persons.

9.2.1 Plate bulwarks are to be stiffened by a strong rail section and supported by stays from the deck. The spacing of these stays forward of 0.93L _R is to be not more than 1,2 m. Elsewhere, bulwark stays are to be not more then 1,83 m apart. Where bulwarks are cut to form a gangway or other opening, stays of increased strength are to be fitted at the ends of the openings. Bulwarks are to be adequately strengthened in way of eyeplates for RAS points, and in way of mooring pipes the plating is to be doubled or increased in thickness and adequately stiffened.

9.2.2 Bulwarks should not be cut for gangway or other openings near the breaks of superstructures, and are also to be arranged to ensure their freedom from main structural stresses. See shell plating in appropriate Chapters.

9.2.3 The section modulus, Z, at the bottom of the bulwark stay is to be not less than:

where

9.2.4 In the calculation of the section modulus, only the material connected to the deck is to be included. The bulb or flange of the stay may be taken into account where connected to the deck, and where, at the ends of the ship, the bulwark plating is connected to the sheerstrake, a width of plating not exceeding 600 mm may also be included. The free edge of the stay is to be stiffened.

9.2.5 Bulwark stays are to be supported by, or to be in line with, suitable underdeck stiffening, which is to be connected by double continuous fillet welds in way of the bulwark stay connection.

9.3.1 The following requirements are applicable to all ship types.

9.3.2 Where bulwarks on the weather decks or superstructure decks form wells, ample provision is to be made for rapidly freeing the decks of large quantities of water by means of freeing ports, and also for draining them.

9.3.3 The minimum freeing area on each side of the ship, for each well on the weather deck is to be derived from the following formulae:

1. where the length, l, of the bulwark in the well is 20 m or less: area required = 0,7 + 0,035l m²

2. where the length, l, exceeds 20 m, area required = 0,07l m²

l need not be taken greater than 0,7L _R, where L _R is the length of the ship as defined in Vol 1, Pt 3, Ch 1, 5.2 Principal particulars.

9.3.4 If the average height of the bulwark exceeds 1,2 m or is less than 0,9 m, the freeing area is to be increased or decreased, respectively, by 0,004 m² per metre of length of well for each 0,1 m increase or decrease in height respectively.

9.3.5 The minimum freeing area for each well on a superstructure is to be half the area calculated from Vol 1, Pt 3, Ch 4, 9.3 Freeing arrangements 9.3.3.

9.3.6 Two-thirds of the freeing port area required is to be provided in the half of the well nearest to the lowest point of the sheer curve.

9.3.7 When the deck has little or no sheer, the freeing area is to be spread along the length of the well.

9.3.8 In ships with no sheer the freeing area as calculated from Vol 1, Pt 3, Ch 4, 9.3 Freeing arrangements 9.3.3 is to be increased by 50 per cent. Where the sheer is less than the standard, as given in Table 4.9.1 Standard sheer profile, the percentage is to be obtained by linear interpolation.

9.3.9 Where the length of the well is less than 10 m, or where a deckhouse occupies most of the length, the freeing port area will be specially considered but in general need not exceed 10 per cent of the bulwark area.

9.3.10 Where it is not practical to provide sufficient freeing port area in the bulwark, particularly in small ships, credit can be given for bollard and fairlead openings where these extend to the deck.

9.3.11 Where a deckhouse has a breadth less than 80 per cent of the beam of the ship, or the width of the side passageways exceeds 1,5 m, the arrangement is considered as one well. Where a deckhouse has a breadth equal to or more than 80 per cent of the beam, B, of the ship, or the width of the side passageways does not exceed 1,5 m, or when a screen bulkhead is fitted across the full breadth of the ship, this arrangement is considered as two wells, before and abaft the deckhouse.

9.3.12 Suitable provision is also to be made for the rapid freeing of water from recesses formed by superstructures and deckhouses, etc. in which water may be shipped and trapped. Deck gear is not to be stowed in such a manner as to obstruct unduly the flow of water to freeing port.

9.3.13 The lower edges of freeing ports are to be as near to the deck as practicable, and should not be more than 100 mm above the deck.

9.3.14 Where freeing ports are more than 230 mm high, vertical bars spaced 230 mm apart may be accepted as an alternative to a horizontal rail to limit the height of the freeing port.

9.3.15  Where shutters are fitted, the pins or bearings are to be of a non-corrodible material, with ample clearance to prevent jamming. The hinges are to be within the upper third of the port. Shutters are not to be fitted with securing appliances.

9.3.16 All ships are to have open rails for at least half the length of the exposed part of the weather deck. Alternatively, if a continuous bulwark is fitted, the minimum freeing area is to be at least 33 per cent of the total area of the bulwark. The freeing area is to be placed in the lower part of the bulwark.

9.3.17 In ships having superstructures which are open at either or both ends to wells formed by bulwarks on the open deck, adequate provision for freeing the open spaces are to be provided as follows:

The freeing port area, A _w for the open well:

The freeing port area, A _s for the open superstructure:

where

To adjust the freeing port area for the distance of the well deck above the weatherdeck, for decks located more than 0,5h _s above the weatherdeck, multiply by the factor 0,5 (h _s/h _w).

9.3.18 Where a ship operates for extended periods in a cold weather environment, see Vol 1, Pt 5, Ch 2, 4.2 Definitions 4.2.3, closing devices fitted to freeing port arrangements are to remain effective. The arrangement will be specially considered.

9.4.1 The effectiveness of the freeing port area in bulwarks of vessels not fitted with a continuous deck obstruction, depends on the free flow across the deck.

9.4.2 The free flow area is the net total longitudinal area of the transverse passageways or gaps between hatchways and superstructures or deckhouses, due account being made for any obstructions such as equipment or other fittings. The height of passageways or gaps used in the calculation of the area is the height of the bulwark.

9.5.1 Walkways are to be designed to an agreed specified standard.

9.5.2 Plans are to be submitted showing the proposed scantlings and arrangements of the structure.

9.5.3 The design loads used are to be as given in Vol 1, Pt 5, Ch 3, 5.3 Pressure on internal decks, Pin 5.3.1. Where it is intended that the walkway be used for the transfer or storage of equipment or other substantial items, the design loads are to be agreed considering the loads given in Vol 1, Pt 5, Ch 3, 5.3 Pressure on internal decks, Pin 5.3.1.

9.5.4 For the design of the supporting structure of walkways, the applicable self weight of the walkway structure is to be added to the total load derived in Vol 1, Pt 3, Ch 4, 9.5 Walkways 9.5.3.

9.6.1 Safety netting used around flight decks is to be arranged so as to safely arrest the fall of personnel. For this purpose the netting is to be raised at the outboard edge by an approximate angle of 10 degrees to the horizontal. The netting is to extend a minimum of 1,25 metres in the horizontal plane. It is recommended that the outboard edge is not above the level of the landing area but in no case is it to protrude greater than 250mm. Materials for the netting are to be specially considered, due consideration is to be given to the fire resistance and weathering properties.

9.6.2 The design load applied to safety nets and their supporting structure is to be taken as 2,7kN per metre of netting acting at the centre of the net in addition to the self-weight of the structure. The sag of the net is to be considered when resolving this force at the inner and outer fixings of the net, see Figure 4.9.1 Safety netting sag. Where the netting terminates at a support, the full load is to be applied to the support. The stress criteria to be applied for supports and supporting structure are given in Table 4.9.2 Permissible stress.

9.7.1 Fixed ladders of any type are to be designed in accordance with an appropriate recognised Standard, e.g. BSMA 39-1 Vertical steel ladders, BSMA 39-2 Sloping steel ladders.

9.7.2 Ladders may be constructed from alternative materials than those specified in the standards for the purposes of satisfying radar signature requirements. Equivalent levels of usability and robustness are to be demonstrated.

9.7.3 When the climbing height of a single ladder is 3m or more, fall arrest features are to be provided. Where practicable, staging platforms are to be provided for climbing heights in excess of 6m so as to divide the climbing height into multiple stages.

9.8.1 A means of embarkation to and disembarkation from vessels for use in harbour or for alongside operations in open sea conditions is to be provided in accordance with an appropriate standard, e.g. IMO MSC.1/Circular.1331 – Guidelines for Construction, Installation, Maintenance and Inspection/Survey of Means of Embarkation and Disembarkation – (11 June 2009).

9.8.2 Accommodation ladders, embarkation ladders and gangways are to be in accordance with an appropriate recognised Standard, e.g. ISO 5488 Accommodation ladders, ISO 5489 Embarkation ladders or ISO 7061 Shipbuilding – aluminium shore gangways for seagoing vessels.