Section 11 Ships for alternate carriage of oil cargo and dry bulk cargo

11.1.1 The requirements of this Section apply to ships intended to carry oil in bulk with a flash point not exceeding 60° (closed-cup test) or dry bulk cargo alternatively.

11.1.2 In addition to this Chapter the requirements of Pt 4, Ch 7 Bulk Carriers and Pt 4, Ch 11 Ore Carriers are also to be complied with as applicable. Particular attention is drawn to the minimum thickness requirements of Pt 4, Ch 9, 10 Construction details and minimum thickness.

11.2.1 Ships complying with the requirement of this section will be eligible for one of the following class notations, as applicable.

1. 100A1 Oil or Bulk Carrier, ESP

2. 100A1 Oil or Bulk Carrier strengthened for heavy cargoes, holds ... may be empty, ESP

3. 100A1 Oil or Bulk Carrier strengthened for heavy cargoes, any hold may be empty, ESP

4. 100A1 Ore or Oil Carrier, ESP.

11.2.2 The notation ESP serves to identify the ship as being subject to an Enhanced Survey Programme as detailed in Pt 1, Ch 3, 3 Intermediate Surveys - Hull and machinery requirements and Pt 1, Ch 3, 6 Special Survey - Bulk carriers - Hull requirements and Pt 1, Ch 3, 7 Special Survey - Oil tankers (including ore/oil ships and ore/bulk/oil ships) - Hull requirements, see also Pt 1, Ch 2, 2.3 Class notations (hull) 2.3.12.

11.2.3 The above notations assume that dry cargoes and oil cargoes will not be carried simultaneously. However, oil may be retained in slop tanks when the ship is carrying dry cargo, provided that these tanks comply with the requirements of the Rules. Gas freeing, inerting, and isolating by approved arrangements of the remaining tanks and holds before loading ore or other dry cargoes is the responsibility of the Owner and is to be in accordance with National and Port Authority requirements.

11.2.4 The Regulations for classification and the assignment of class notations are given in Pt 1, Ch 2 Classification Regulations to which reference should be made.

11.3.1 The requirements contained in this Section apply to the following ship types:

1. Oil or bulk carrier with a basic structural configuration having a single deck hull and which includes, a double skin side structure, double bottom, hopper side tanks and topside tanks fitted below the upper deck. A typical cross-section is indicated in Figure 9.11.1 Structural configuration. However, consideration will be given to other arrangements on the basis of the requirements of this Section. The requirements of Pt 4, Ch 7 Bulk Carriers are to be applied.

2. Ore or oil carrier with a basic structural configuration having a single deck hull and which includes, a double skin side structure, two longitudinal bulkheads, and a double bottom throughout the centre hold and wing tanks. A typical cross-section is indicated in Figure 9.11.1 Structural configuration. The requirements of Pt 4, Ch 11 Ore Carriers are to be applied.

Figure 9.11.1 Structural configuration

11.3.2 Where oil residues are to be retained on board, slop tanks of sufficient capacity to meet MARPOL requirements are to be provided and are to be separated from adjacent spaces by cofferdams which are to be capable of being flooded, except where the adjacent space is used as a pump-room, ballast tank, or a fuel oil bunker tank, see also Pt 4, Ch 9, 1.2 Application and ship arrangement 1.2.2, Pt 5, Ch 15, 1.9 Non-sparking fans for hazardous areas and SOLAS Reg. II-2 Part D - Escape.

11.3.3 Arrangements are to be provided for the mechanical ventilation of cargo spaces and any enclosed spaces adjacent to cargo spaces, see Pt 5, Ch 15, 3 Cargo handling system. Similar arrangements are to be provided for cargo oil ducts which are used as pipe tunnels when the ship is carrying dry cargo, see also Pt 4, Ch 9, 11.3 Structural configuration and ship arrangement 11.3.5.

11.3.4 Openings which may be used for cargo operations, for example in the bottom of topside tanks, are not permitted in bulkheads and decks separating oil cargo spaces from other spaces not designed and equipped for the carriage of oil cargoes unless such openings are equipped with alternative approved means to ensure equivalent integrity.

11.3.5  For the requirements of ducts for cargo oil lines below decks on ore or oil carriers, see Pt 5, Ch 15, 3.3 Cargo piping system.

11.3.6 For the requirements for access arrangements to pipe tunnels and spaces in the cargo area, see Pt 4, Ch 9, 13 Access arrangements and closing appliances.

11.4.1 In way of cargo oil holds, the scantlings of the cargo space boundaries are to comply with Pt 4, Ch 9, 11.4 Bulkheads in way of dry/oil cargo holds 11.4.2 and Pt 4, Ch 9, 11.4 Bulkheads in way of dry/oil cargo holds 11.4.6.

11.4.2 The scantlings of vertically corrugated and double plate transverse bulkheads supported by stools are to be determined in accordance with the requirements of Pt 4, Ch 9, 7.4 Bulkheads supported by stools 7.4.1, Pt 4, Ch 9, 7.4 Bulkheads supported by stools 7.4.2 and Pt 4, Ch 7, 10.2 Bulkheads supported by stools. In general, the bulkheads are to have stiffening or corrugations arranged vertically, supported by top and bottom end stools. Alternative arrangements will, however, be considered.

11.4.3 The longitudinal bulkheads including bulkhead forming inner hull, and the sloped bulkheads of the topside and double bottom tanks are to comply with Pt 4, Ch 9, 6 Inner hull, inner bottom and longitudinal oiltight bulkheads. However, in way of cargo holds b ₁ is to be taken as the horizontal distance from the plate or longitudinal under consideration to the vertical projection of the hatch side furthest away from the bulkhead. For longitudinal framing the determination of the span point may be in accordance with Pt 3, Ch 3, 3 Structural idealisation. The scantlings of the sloped bulkhead of the double bottom hopper tanks in way of the dry cargo holds are to be not less than the requirements of Pt 4, Ch 7, 9 Hopper side tank structure.

11.4.4 The arrangement of stools and adjacent structure common with dry cargo holds is to be designed to avoid pockets in which gas could collect.

11.4.5  Where the form of construction used for transverse bulkheads in wing tanks is different from that used in centre holds, arrangements are to be made to ensure continuity of transverse strength through the longitudinal bulkhead.

11.4.6 Where partial filling of centre holds with liquid is contemplated, the scantlings and structural arrangements of the boundary bulkheads are to be capable of withstanding the loads imposed by the movement of liquid in the holds. The magnitude of the predicted loadings, together with the scantling calculations, may require to be submitted.

11.5.1 Oiltight bulkheads in wing tanks of ore or oil carriers, see Pt 4, Ch 9, 11.3 Structural configuration and ship arrangement 11.3.1.(b) are to comply with the requirements for transverse oiltight bulkhead plating, stiffening and primary structure given in Pt 4, Ch 9, 7 Transverse oiltight bulkheads and Pt 4, Ch 9, 9 Primary members supporting longitudinal framing.

11.5.2 Non-oiltight bulkheads in wing tanks are to comply with the requirements given in Pt 4, Ch 9, 8 Non-oiltight bulkheads and Pt 4, Ch 9, 9 Primary members supporting longitudinal framing. The bulkhead plating is to be suitably reinforced in way of double bottom scarfing arrangements and the ends of centre hold deck transverses. Openings in wing tank bulkheads are to be kept clear of these areas.

11.6.1 The scantlings of cofferdam bulkheads not forming the boundary of a cargo space are to be as required by Pt 4, Ch 9, 7 Transverse oiltight bulkheads.

11.7.1 The scantlings of the cargo hold hatch coamings are to comply with Pt 3, Ch 11, 5 Hatch coamings and the cargo hold hatch covers with Pt 3, Ch 11, 2 Steel hatch covers and Pt 4, Ch 7, 12 Steel hatch covers.

11.7.2  Where cargo holds are intended to be partly filled the hatch covers may require to be additionally strengthened, see also Pt 4, Ch 9, 11.4 Bulkheads in way of dry/oil cargo holds 11.4.6.

11.7.3 Slop tank hatches and cleaning openings are only permitted on open deck. Unless these openings are closed with a watertight bolted plate, the locking arrangements are to be under the control of a responsible officer.

11.8.1 The height and construction of hatch coamings are to comply with Pt 3, Ch 11, 5 Hatch coamings and Pt 4, Ch 7, 13 Hatch coamings.