Section 4 External vehicle ramps

4.1.1 This Section applies to movable external vehicle ramps (e.g. stern ramp, bow ramp and side ramp) installed on ships where the loading or unloading operation is carried out in a harbour or sheltered water, i.e. Standard Service Category.

4.1.2 Where the vehicle ramp is designed to operate in conditions other than those defined in Ch 6, 4.1 General 4.1.1, the design will be specially considered, i.e. Specified Service Category.

4.1.3 For the lowered position (harbour), the ramp is to be considered for the worst possible combination of angles and support arrangement (supported by the quay and/or its hoisting mechanism) 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 including twist of ramp by difference of roll/trim angle and quay.

5. Lateral forces on hinges due to friction between ramp and quay.

4.1.4 For raising and slewing manoeuvres (harbour), the ramp is to be considered with respect to the following forces:

1. Self-weight.

2. Applied load, where appropriate.

3. Dynamic forces due to hoisting/slewing.

4. Forces due to ship’s static inclinations.

5. Environmental load as applicable.

4.1.5 For the sea-going condition, the stowed position or in cases of shell openings, the closed position of the ramp and its locking mechanism are to be considered with respect to the following forces:

1. Self-weight.

2. Applied load, where appropriate.

3. Forces due to ship motion and static inclination.

4. Environmental load as applicable.

4.1.6 The ramp is to be considered with respect to design loads and requirements stated in Ch 6, 2 Loading and design criteria.

4.2.1 The self-weight load, L _w, is to be taken as the weight of the ramp and is to be multiplied by 1,2 to take account of the dynamic forces due to manoeuvring the ramp.

4.2.2 The applied load, L _c, is the static load on the ramp due to cargo or vehicles and is to be multiplied by 1,1 to take account of vehicle movement. In cases where ramps are designed such that this factor can be higher than 1,1, the factor will be specially considered.

4.2.3 When the ramp is manoeuvred whilst loaded, both L _w and L _c are to be multiplied by 1,2.

4.3.1 The slope of the ramp is not to exceed 1 in 10 and where the ramp is designed for ship to shore use, this angle is to include the effects of heel and trim defined in Ch 6, 2.4 Forces due to ship motion 2.4.2. Where a ramp is designed to operate at a greater slope, it will be subject to special consideration.

4.4.1 For ramps forming part of a shell, see also Ch 6, 4.1 General 4.1.5. The ramps are 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.

4.4.2  Case 1: The ramp 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, 4.1 General 4.1.3. This is represented by the following expression:

L _w + 1,1L _c + L _h1 + L _h2 + L _h3

4.4.3  Case 2: Usually, external ramps are unloaded in the sea-going condition. For exceptional cases where the ramp is loaded, it is to be considered with respect to the forces resulting from the accelerations due to ship motion, together with the forces due to consideration of static inclination as defined in Ch 6, 4.1 General 4.1.5, together with weather forces as appropriate.

4.4.4 Case 3: The ramp is 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 ramp is further to be considered with respect to self-weight plus the applied test load multiplied by 1,2. This is represented by the following expression:

1,2 (L _w + L _t)

where

4.4.5  Case 4: The vehicle ramps are 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, 4.1 General 4.1.4. This is represented by the following expression:

1,2 (L _w + L _c) + L _h1 + L _h2 + L _h3 + L _wind

where

The wind speed for manoeuvring operation is not to be less than 20 m/s and where it is anticipated that it will exceed that, these higher wind speeds are to be considered.

4.5.1 In general, the sea-going condition stowage locks and cleating devices are to be in compliance with the requirements of the Rules for Ships, as appropriate.

4.5.2 The locking cylinder must be of an approved type, fitted with an internal mechanical lock and is to be tested on board.