6 WATER FREEING ARRANGEMENTS
Objective:- This section provides for consideration of the risks of green water being shipped aboard and the resulting consequences with respect to the vessels stability and safety of personnel on deck.
6.1 The standards for water freeing arrangements should comply with ICLL as far as it is reasonable and practicable to do so.
In any case the intention should be to achieve a standard of safety which is at least equivalent to the standard of ICLL.
In applying freeing port requirements of ICLL, the following correction to the required freeing port area may be applied:-
FP REQ = FP MAX *( A ACT / A MAX )
Where
FP REQ = Freeing port area required
FP MAX = Maximum freeing port area required
A ACT = Actual area of deck fitted with enclosed bulwarks, excluding superstructure or deckhouse area
A MAX = Area of maximum sized well (0.7L x B) where L and B are the dimensions of the vessel
On sailing vessels, where the solid bulwark height does not exceed 150mm, specific freeing ports, as defined above, are not required.
6.2 In individual cases, when the Administration considers that the requirements of ICLL cannot be met, the Administration may consider and approve alternative arrangements to achieve adequate safety standards. Freeing arrangements may take account of a reduced permeability and volume of the well, when compared to a full size well.
In considering an individual case, the Administration will take into account the vessels past performance in service and the declared area(s) of operation and any other conditions which restrict the use of the vessel at sea which will be recorded on the load line certificate issued to the vessel. (See section 4.1.)
6.3 Recesses
6.3.1 Any recess in the weathertight weather deck should be of weathertight construction and should be self draining under all normal conditions of heel and trim of the vessel.
A swimming pool or spa bath open to the elements should be treated as a recess.
6.3.2 The means of drainage provided should be capable of efficient operation when the vessel is heeled to an angle of 10 0 in the case of a motor vessel (see 10A.2), and 30 0 in the case of a sailing vessel.
The drainage arrangements should have the capability of draining the recess (when fully charged with water) within 3 minutes when the vessel is upright and at the load line draught. Means should be provided to prevent the backflow of sea water into the recess.
6.3.3 When it is not practical to provide drainage which meets the requirements of 6.3.2, alternative safety measures may be proposed for approval by the Administration. Where the above requirements for quick drainage cannot be met, the effect on intact and damage stability should be considered taking into account the mass of water and its free surface effect.