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Free Surface Effects
When using the sequential method, the free surface moments of all tanks are to be set to the maximum for stability and strength calculations.
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Forward and Aft Drafts
Forward Draft
In all sequences of ballast water exchange, the forward draft of the vessel is to be greater than the prescribed minimum forward draft as shown in the Trim and Stability Booklet. If, for a transitory period or in a specific sequence, the minimum forward draft cannot be satisfied, the Ballast Water Management Plan is to identify the stages of the exchange process that do not meet the criteria for minimum forward draft, and a footnote documenting this is to be assigned to the relevant stages. The following is an example of such a footnote:
“Exchange of ballast in tanks …. is to be carried out in favorable sea conditions such that the risk of forward slamming is minimized (Beaufort Force less than or equal to 7).”
Aft Draft
Full propeller immersion is assumed as the minimum requirement for the aft draft.
