The following article may be of interest for all persons who are engaged with the stowage and securing of all types of cargo and especially of exceptionally large cargo units on sea-going vessels. Such persons are mariners, transport engineers, warranty surveyors and representatives of all commercial parties of the particular transport project, including their underwriters' risk managers.
Since 1995 the proper stowage and securing of cargo items on ships has been supported by the Annex 13 of the IMO Code of Safe Practice for Cargo Stowage and Securing (CSS-Code). This Code does not present mandatory regulations. It is rather classified as an adopted industry standard. But what is more important, it has proved its value compared to the previous incertitude of opinions, hearsay and casualness sprawling in the wake of globalisation of shipping in the second half of the 20th Century.
The Annex 13 contains a concise but flexible calculation method which enables a competent user to assess any semi- and non-standardised securing arrangement. At the time the method was 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. But the past twenty years have shown a considerable increase of such extraordinary shipments together with the trustful habit of users to readily apply the Annex 13 also for them. Therefore it appears advisable to adapt or upgrade the provisions of the Annex 13 by the following topics:
Weather dependent load assumptions for cargo securing (A)
Speed reduction in head seas as accepted operational parameter (A)
Vessel survival criteria in case of a major cargo shift (A)
Additional tipping moment due to the rotational inertia of cargo units (A)
Balance of longitudinal sliding and tipping (A)
Interpretation of "on deck high" (B)
Separate consideration of wind moment in tipping balances (B)
Homogeneity of securing arrangements (B)
The above topics are marked with the category labels (A) and (B). Category (A) will need the approval of IMO, because the proposals therein require the agreement of new benchmarks. Category (B) may be applied immediately, because the proposals remain within the scope of responsible application of the existing Annex 13.