Section 5 Container securing arrangements for stowage on exposed decks without cell guides

5.1.1 Containers stowed on deck or on hatch covers are generally to be aligned in the fore and aft direction (longitudinally stowed), but alternative arrangements will be considered.

5.1.2 Containers are to be stowed so that they do not extend beyond the ship’s side. Adequate support is to be provided where they overhang hatch coamings or other deck structures. The stowage arrangements are to be such as to permit safe access for personnel in the necessary working of the ship, and to provide sufficient access for operation and inspection of the securing devices.

5.1.3 Where containers are stowed on hatch covers, the covers are to be effectively restrained against sliding by approved type stoppers or equivalent. Details of the locations of stoppers relative to the supporting structure are to be submitted at an early stage.

5.1.4 Stanchions and similar structure supporting containers and securing devices, such as D-rings for lashings, are to be of adequate strength for the imposed loads and of sufficient stiffness to minimise any deflection which could lead to a reduction in the effectiveness of the securing device.

5.1.5 In the region forward of 0,75L, additional securing devices may be required due to green sea forces, see Pt 3, Ch 14, 8.2 Ship motion, wind and green sea forces acting on containers 8.2.4.

5.1.6 In general, stowage of heavy containers on top of lighter containers is to be avoided, unless validated as being satisfactory by an approved onboard lashing program or covered by the approved container securing arrangement.

5.1.7 Approved semi-automatic and fully-automatic fittings and twistlocks are to be used.

For fittings where the locking method requires defined clearances between the corner castings and the fixed foundations, such fittings are not to be used at the lowest tier of a stack which is resting with one side on a hatch cover panel and bridging to a container stanchion. The same applies if the stack is resting on different hatch cover panels or foundations where relative deflection during ship operation can occur.

5.2.1 Containers are to be secured at their lower corners by approved locking devices.

5.2.2 Alternatively, containers may be secured by lashings fitted diagonally or vertically at both ends of each container, in association with cone fittings at each container corner.

5.3.1 Containers are to be secured at their lower corners at each tier by approved locking devices.

5.3.2 Where the calculations indicate that separation forces will not occur at any point in the stack, double stacking cones may be fitted at all internal corners of the stack and bridge fittings used to connect the tops of the rows in the transverse direction. Locking devices are to be fitted at all external corners.

5.3.3 Alternatively, containers may be secured by lashings in association with stacking cones or, where the calculations indicate that separation forces may occur, with locking devices.

5.4.1 Containers are to be secured at their lower corners at each tier by approved locking devices.

5.4.2 Alternatively, containers may be secured by lashings. One or two tiers of lashings may be fitted in association with stacking cones or, where the calculations indicate that separation forces may occur, with locking devices.

5.4.3 When lashings are employed, they are usually fitted to the bottom corner casting of a container. Proposals to attach lashings to the top casting of a container will be considered. The reduced strength of the upper corner casting compared to the lower corner castings is to be taken into account.

5.4.4 Internal lashings arranged in pairs (internal para-lash arrangements) are acceptable. Lashings in pairs are generally to be attached one to the bottom corner casting of the upper tier and the other to the top corner casting of the lower tier container. Suitable connections are to be provided at the lower ends. See also Table 14.3.2 Test loads and test modes for loose container securing fittings.

5.4.5 Approved semi-automatic or fully-automatic fittings may be used with internal lashing or external lashing arrangements.

5.4.6 For external lashing arrangements, if the stack forces are such that lifting occurs at the uppermost lashing connection point, then the force in the lashing device is to include allowance for the lifting force. The effect of lifting at lashing point connections below the uppermost connection may be ignored.

5.4.7 The LR approval process for fully-automatic fittings includes a requirement that the fitting passes a tensile load test. This test specifies a maximum allowable vertical separation under the tensile load and therefore the effect of the magnitude of the opening clearance under tensile loads may be ignored in the calculation of the additional vertical force in the lashing rod. For semi-automatic twistlocks used with external lashings, the nominal clearance of the fitting is not to exceed the maximum values specified in the LR test procedure. Non-LR approved fittings will be specially considered, see Pt 3, Ch 14, 3.1 General 3.1.3.

5.4.8 Proposals to use horizontal lashings connected to lashing bridges will be specially considered. The forces in such securing systems are to be determined by direct calculations, taking into account the following effects:

• stiffness of the container walls, the lashings and the lashing bridge; and
• the possible horizontal displacements of the containers relative to the lashing bridge due to the clearances of the hatch cover stoppers and the container securing fittings.

5.4.9 When vertical lashings are used in combination with container securing fittings, consideration is to be given to the vertical clearances between the fittings and the container corner castings.

5.4.10 For stowage arrangements incorporating fully-automatic fittings which do not mechanically secure the container in pure vertical direction when subject to vertical motions, it is to be ensured that no separation occurs under the load cases specified in Pt 3, Ch 14, 8 Determination of forces for container securing arrangements. In addition, where stacks in the outermost position, anywhere in the length of the vessel, are secured with fully-automatic fittings without lashings, provisions such as breakwaters, effective side screens, plated bulwarks or similar, are to be provided to prevent the possibility of green sea buoyancy forces causing the containers to disengage, see Pt 3, Ch 14, 8.2 Ship motion, wind and green sea forces acting on containers 8.2.10. Alternatively, the lowest tier of containers is to be secured by manual or semi-automatic twistlocks.

5.4.11 If the carriage of one or more tiers of 20 ft containers being overstowed with at least one tier of 40 ft containers, the so-called ‘Russian Stow Arrangement’, is desired, the following requirements apply.

1. At the 20 ft gap the containers are to be secured by means of midlocks, whereas the fore and aft ends are to be secured by twistlocks and if necessary supplemented by lashing rods.

2. The 40 ft overstow container is to be secured by twistlocks or if necessary with a combination of twistlocks and lashing rods. The stack is to be assessed in a twostep procedure, as follows:

   1. For location at the 40 ft ends, the entire mixed stack is to be considered as a 40 ft stack. The weights of the 40 ft containers are to be considered in the calculations. For the tiers of 20 ft containers, the weight of one 20 ft container is to be taken as the basis for the calculation at each tier.

   2. For the location of the 20 ft tiers at the mid-bay position, the assessment is to be carried out as for an unlashed stack. The 40 ft overstow container does not need to be taken into consideration.

5.4.12 No lashings are to be applied to the ends of a 45 ft, 48 ft or 53 ft container if stowed on top of a shorter unit.

5.5.1 Where the containers are supported on bearers placed to distribute the stackweight as Line Loads, the following requirements are to be complied with:

1. The stack is, in general, to comprise a maximum of two tiers of loaded containers.

2. The load from the upper tier is to be transferred through the container corners. Line loading is not to be used between tiers.

3. The load on each vertical corner post of the bottom tier, calculated in accordance with Pt 3, Ch 14, 9 Strength of container securing arrangements, is not to exceed one half of the Rated Load of the container.

4. Where the calculations indicate that lifting forces may occur, locking devices are to be fitted at the container corners.

5. The clearance below the bottom container corner casting is to be such that the stacking cone or equivalent cannot be dislodged under shear loading.

5.5.2 Where an approved Line Load stowage system is installed, the special features notation will be suitably modified.

5.6.1 Containers may be secured by the use of a fixed structure providing permanent buttresses in association with portable frameworks. Proposals to adopt such systems will be considered on the basis of the loads developed in the structure and the corresponding stresses.

5.6.2 The framework or other devices securing the containers are to be aligned with the container corner castings and any clearance gap is to be kept to the minimum to reduce shifting.