Water Freeing Arrangements

6

Water Freeing Arrangements

This section provides for consideration of the risks of green water being shipped aboard and the resulting consequences with respect to the yacht's stability and safety of personnel on deck.

6.1 General

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. Additionally, where a well is created on each side of the yacht between a superstructure or deckhouse, and the bulwark in way of that superstructure or deck house, the following formula may be used to determine the required freeing port areas on each side of the yacht for the well concerned:

FPREQ

= 0.28×AwB

Where:

FPREQ = Freeing port area required

Aw

= Area of well in way of superstructure or deckhouse B = Full beam at deck

On sailing yachts, 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. For Short Range Yachts it is considered that the requirement for freeing port area for a forward or after well may be reduced by a form factor equal to the ratio of (actual area well) divided by (length of well x breadth of well). Dimensions should be taken at half height of the bulwark. This may be reduced by 50% providing it can be shown that the intact stability of the yacht remains acceptable if the well is flooded to any level up to the bulwark height and that area provided will allow the well to drain in less than three minutes. In considering an individual case, the Administration will take into account the yacht's past performance in service and the declared area(s) of operation and any other conditions which restrict the use of the yacht at sea which will be recorded on the load line certificate issued to the yacht. (See section 4.1.3.)

6.3 Recesses

6.3.1 Any recess in the weather deck should be of weathertight construction and should be self-draining under all normal conditions of heel and trim of the yacht. 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 yacht is heeled to an angle of 10° in the case of a motor yacht (see 10.2), and 30° in the case of a sailing yacht. The drainage arrangements should have the capability of draining the recess (when fully charged with water) within three minutes when the yacht 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.