Section 2 Definitions

2.1.1 The freeboard deck is normally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all openings in the weather part, and below which all openings in the sides of the unit are fitted with permanent means of watertight closing. For semi-submersible units, see also Pt 4, Ch 7, 5.2 Column-stabilised units and tension-leg units 5.2.4.

2.2.1 Freeboard is the distance measured vertically downwards amidships from the upper edge of the deck line to the upper edge of the related load line.

2.3.1 A closing appliance is considered weathertight if it is designed to prevent the passage of water into the unit in any sea conditions.

2.3.2 Generally, all openings in the freeboard deck and in enclosed superstructures are to be provided with weathertight closing appliances.

2.4.1 A closing appliance is considered watertight if it is designed to prevent the passage of water in either direction under a head of water for which the surrounding structure is designed.

2.4.2 Generally, all openings below the freeboard deck in the outer shell boundaries and in main watertight decks and bulkheads are to be fitted with permanent means of watertight closing.

2.4.3 When the Rules require closing appliances with closely bolted covers, the pitch of the securing bolts is not to exceed five diameters.

2.5.1 For the purpose of Load Line conditions of assignment, there are two basic positions of hatchways, doorways and ventilators defined as follows:

Position 1 – Upon exposed freeboard and raised quarterdecks, and exposed superstructure decks within the forward 0,25.

Position 2 – Upon exposed superstructure decks abaft the forward 0,25.

where

= the load line length in accordance with the International Convention on Load Lines, 1966.

2.5.2 The application to column-stabilised units will be specially considered, see Pt 4, Ch 7, 5.2 Column-stabilised units and tension-leg units 5.2.4.

2.6.1 The damage waterline is the final equilibrium waterline after damage defined in the applicable stability Regulations, see Pt 4, Ch 7, 1.1 Application 1.1.2.

2.7.1 The intact stability waterline is the most severe inclined waterline to satisfy the range of intact stability defined in the applicable stability Regulations, see Pt 4, Ch 7, 1.1 Application 1.1.2.

2.8.1 Down flooding means any flooding of the interior of any part of the buoyant structure of a unit through openings which cannot be closed watertight or weathertight, as appropriate, in order to meet the intact or damage stability criteria or which are required for operational reasons to be left open.

2.8.2 The down flooding angle is the least angle of heel at which openings in the hull, superstructure or deckhouses, which cannot be closed weathertight, immerse and allow flooding to occur.

2.8.3 Intact stability is to comply with Pt 1, Ch 2, 1 Conditions for classification.