Following delays due to Covid-19, the IMO’s Maritime Safety Committee has now approved and adapted amendments to the Code of Safe Practice for Cargo Stowage and Securing (CSS) code during its 102nd session which were first finalised in September 2019. This amendment relates to weather-dependent lashing, heavy cargo items and semi-standardised cargoes such as vehicles on ro-ro ships. The IMO’s CSS code provides best-practice guidelines for cargo lashing principles for non-standardised cargoes requiring individual stowage and securing arrangements. Thus any cargoes with the exception of containers and bulk cargoes.
Various changes have been made and approved to Annex 13 of the CSS Code, a brief summary is listed below:
- Expansion of Scope to include semi-standardised cargoes and inclusion of a new Appendix 4 containing “Advanced provisions and considerations applicable to semi-standardised cargoes”.
- The provisional welding of stoppers intended for prevention of cargo sliding has now been carefully included as a general rule of thumb of 4kN/cm of welded seam, whereas before this was completely excluded from this code.
- Warning of the combined use of stiff and flexible securing arrangements, limiting the contribution in calculations.
- The introduction of a simple empirical formula for the calculation of a reduction factor which takes into account uncertainties when operating in a restricted area for weather-dependent lashing. This reduction factor is then applied onto accelerations obtained from previously-existing tables (2 & 4) in Annex 13.
- The extrapolation of table 4 to take into account vessels having large GM-values of 7 and above, with previous figures for vessels with GM values less than 6 remaining unchanged.
- More constructive advice regarding friction increasing materials.
- The introduction of a correction factor which slightly reduces the simultaneous vertical acceleration when analysing the mutual relation of simultaneous vertical and longitudinal accelerations which, in turn, lower the friction to ground and resistance of cargo to tipping. A corresponding coefficient of friction is then selected according to a table depending on the calculated correction factor.
- Change to the definition of the term “service speed” when calculating longitudinal and vertical accelerations in the assessment of longitudinal securing arrangements for deck cargoes susceptible to longitudinal sliding and shifting in head seas.
- An addition of a new appendix (3) to Annex 13 with the title: “Advanced Provisions and Considerations Applicable to Very Heavy and/or Large Cargo Items”, which deals with:1) Longitudinal Tipping.
2) Rotational Inertia of large cargo items.
3) Separate consideration of wind and sea sloshing.
4) The interpretation of the stowage level “on deck high” (on table 2 of Annex 13).
5) Structural strength assessment involving concentrated loads on ship structures and load-spreading methods with the use of bedding materials arranged to vessels’ load-bearing structures.
6) Weather Routing to protect sensitive cargo rather than for fuel savings.
7) Considerations to line-of-sight requirements, adequate visibility of navigation lights and unobstructed radar transmission.
- An addition of a new appendix (4) to Annex 13 with the title: “Advanced Provisions and Considerations Applicable to Very Heavy and/or Large Cargo Items”, which outlines further considerations to be taken for the stowage and securing of such cargoes, in addition to those outlined in Chapter 4, Annex 4 and Annex 13. This includes the following considerations:
1) Performance factor for short voyages, where fast cargo handling and dispatch is of the essence.
2) Asymmetric securing arrangements.
3) The proper use of a reduced safety factor.
4) Frictional Coefficients, outlining new coefficients for different types of rubber tyres on steel decks.
5) The limited securing effect of parking brakes and wheel chocks.
The above amendments to Annex 13 aim to provide better guidance and establishing a more holistic approach to the assessment of cargo securing methods/arrangements, thus taking into account more variables and practical scenarios.
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