Appendix - Floatability Assessment

 1 Introduction

1.1 This floatability assessment is intended to provide a measure of residual stability if category B watertight doors are opened for extended periods of time when navigating in non-hazardous areas if necessitated by work in the immediate vicinity of the door.

1.2 Care should be exercised not to confuse the "floatability assessment" criteria used in this procedure with the requirements in the SOLAS chapter II-1 damage stability regulations.

2 Damage and flooding extent for the floatability assessment

2.1 A floatability assessment calculation should be performed for each category B watertight door. Only the individual category B watertight door under consideration need be assumed open for the calculation.

2.2 The extent of damage to be assumed for the floatability assessment should be as defined in SOLAS regulation II-1/8.3. In addition, watertight compartments inboard of the transverse extent of damage should be assumed flooded, irrespective of whether any longitudinal bulkheads are fitted with watertight doors, if:

• .1 the inboard compartment is within the longitudinal damage extent; and

• .2 the inboard compartment is connected by the watertight door under consideration.

If any lesser damage extents than indicated above would result in a more severe condition with respect to the floatability criteria, then such damage extents should be assumed in the calculations. In this context, the damage extent should be assumed as both penetrating and not penetrating the double bottom.

2.3 The floatability assessment should account for the worst case involving the additional flooding of the compartment connected by the category B watertight door under consideration.

3 Criteria for the floatability assessment

3.1 For each assumed flooding case described in section 2, the floatability criteria described below should be met at the deepest subdivision draught at level trim. For this loading condition, the limiting KG or GM should be assumed in the calculations.

• .1 The bulkhead deck may be immersed provided that no progressive flooding occurs (i.e. weathertight openings may not be immersed; only watertight openings may be immersed).

• .2 The maximum positive righting lever should not be less than 0.05 m.

• .3 The range of positive righting levers should not be less than 7°.

• .4 The maximum equilibrium heel angle should not exceed 15°.

3.2 The Administration may accept alternative methodologies if it is satisfied that at least the same degree of safety as represented by this procedure is achieved (reference is made to SOLAS regulation II-1/4.3).

Explanatory sketches

Notes:

In case of a ship carrying less than 400 persons, the breach should only be considered between transverse bulkheads (if spaced by more than 0.03L).