Section 6 Movable decks

6.1.1 This Section applies to movable vehicle decks installed on ships where the loading or unloading operation is carried out in a harbour or sheltered water, i.e. Standard Service Category.

6.1.2 Where movable vehicle deck is designed to operate in conditions other than those defined in Ch 6, 6.1 General 6.1.1, the design will be specially considered, i.e. Specified Service Category.

6.1.3 For loading and unloading (harbour), the movable vehicle deck is to be considered for the worst possible combination of angles with respect to the following forces:

1. Self-weight.

2. Applied load.

3. Dynamic forces due to vehicle movement.

4. Forces due to ship’s static inclinations.

6.1.4 For raising and lowering manoeuvres (harbour), the movable vehicle deck is to be considered with respect to the following forces:

1. Self-weight.

2. Dynamic forces due to hoisting/lowering.

3. Forces due to ship’s static inclinations.

6.1.5 For the sea-going condition, the movable vehicle deck, its supports and locking mechanism are to be considered with respect to the following forces:

1. Self-weight.

2. Applied load.

3. Forces due to the ship motion and static inclination.

6.1.6 For the stowed position, the unloaded panels and its locking mechanism are to be considered with respect to the following forces:

1. Self-weight.

2. Forces due to the ship motion and static inclination.

6.1.7 The movable vehicle deck is to be considered with respect to design loads and requirements stated in Ch 6, 2 Loading and design criteria.

6.2.1 The movable vehicle deck is to be considered with respect to design loads resulting from the following conditions:

1. Case 1 – Loading and unloading operating.

2. Case 2 – Sea-going or stowed condition.

3. Case 3 – Test load condition.

4. Case 4 – Manoeuvring condition.

6.2.2  Case 1: The movable vehicle deck is to be considered with respect to self-weight plus the applied load multiplied by 1,1, together with the horizontal forces as defined in Ch 6, 6.1 General 6.1.3. This is represented by the following expression:

L _w + 1,1L _c + L _h1 + L _h2

6.2.3  Case 2: The movable vehicle deck, its supports and locking mechanism are to be considered with respect to the forces acting on the self-weight and applied load, as applicable, resulting from accelerations due to ship motion and static inclination as follows:

1. Loaded sea-going condition.

2. Stowed unloaded condition.

6.2.4  Case 3: The movable vehicle deck, its support and locking mechanism are to be considered with respect to the forces due to the self-weight plus the test load. This case is represented by the following expression:

L _w + L _t

The movable vehicle deck is further to be considered with respect to self-weight plus the applied test load as applicable to the lifting of the unloaded installation multiplied by 1,2. This is represented by the following expression:

1,2 (L _w + L _t )

6.2.5  Case 4: The movable vehicle deck is to be considered with respect to self-weight plus the applied load, where applicable, multiplied by 1,2, together with the horizontal forces as defined in Ch 6, 6.1 General 6.1.4. This is represented by the following expression:

1,2 (L _w + L _c ) + L _h1 + L _h2

where

6.3.1 In general, for the sea-going condition, stowage locks are to be fitted.

6.3.2 In cases where the movable vehicle deck is stowed unloaded and locked by interlocking the hoisting system, the arrangement must be specially considered.

6.3.3 The actuator that locks the hoisting system must be of an approved type, fitted with internal mechanical lock and is to be tested on board.

6.3.4 Any Safety at Work requirements, stanchions, etc. are to be such that any risk of getting stuck is avoided. Remaining health and safety requirements of ILO or the appropriate National Flag Administration must be complied with as applicable.

6.3.5 The supporting arrangement is to be such that the movement at the edge of one panel relative to the next does not exceed 50 mm during loading or unloading operation.