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SPOTCHECKSAFETY


How proposed changes will clarify lashing rules


Paul Hoogenhout, senior project engineer at RollDock, discusses some of the proposed changes to Annex 13 of the IMO Code of Safe Practice for Cargo Stowage and Securing (CSS-Code), which provides guidance for the lashing and securing of project cargo.


methods, which enables users to assess non-standardised securing arrangements. The rules become very grey when


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something is classified as project cargo, however. Currently, the regulations are either too indecisive or too conservative, and if we want to guarantee safety in our industry, we need to develop a uniform set of rules with clearer definitions. The article Proposed interpretations of, and


amendments to, the Annex 13 of the IMO Code of Safe Practice for Cargo Stowage and Securing was initially published in 2017 and it stated that when these methods and regulations were designed, its scope of application had been phrased in a way to exclude cargo units with “unusual characteristics” and the use of “relevant expertise” had been prompted instead.


Proposed changes The authors – Hermann Kaps and Peter Andersson – put forward eight changes to the annex that aim to improve the safety and efficiency of cargo securing: clarification of weather-dependent load assumptions; speed reduction in head seas; vessel survival criteria in case of a major cargo shift; additional tipping moment due to the rotational inertia; balance of longitudinal sliding and tipping; interpretation of ‘on deck high’; wind


74 January/February 2020


nnex 13 of the IMO CSS-Code has long supported the stowage and securing of cargo on ships. The adopted industry standard contains flexible calculation


Assembled cranes lashed on the deck of Rolldock Sun.


moment in tipping balance; and homogeneity of securing arrangements. For weather-dependent load


assumptions, the regulations stipulate that load assumptions for cargo securing should be based on the heaviest winds and sea state that has ever been measured in that specific region. For some vulnerable cargo items, an optimal period and route is chosen. This allows the shipping company to pick a reduction model – of which there are many (pictured on page 76). The proposal suggests that the annex should choose one model to create a unified playing field. Another proposal concerns speed


reduction in head seas. To assess the accelerations that the cargo will experience, the current rules demand that the


calculations are done with maximum speed. In reality, a ship with vulnerable cargo onboard in swell will not sail maximum speed in head seas. Therefore, the proposal suggests that calculations for accelerations can be executed with reduced speed.


Rotational inertia The mathematical model used for assessing the suitability of a securing arrangement describes the mass of the cargo as being concentrated at its centre of gravity. This is fairly accurate as long as its length, width or height does not exceed 10 m. Large cargo will produce an additional tipping moment due to the distribution of its mass over a larger volume. The real spatial mass distribution requires the compilation of


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