Section 1 Design loads

1.1.1 The design loads to be applied to nearshore units that will operate in benign environmental conditions can be taken from either a site-specific assessment derived by direct calculation or the Rule values with a ship service factor in accordance with this Section.

1.1.2 To derive realistic environmental loads, direct calculation based on the site-specific assessment should be used. Without any service restriction notation, a ship is expected to be designed for unrestricted worldwide service.

1.1.3 If the unit is classed within the Rules and Regulations for the Classification of Ships, July 2022, it is allowed to relax the hull girder wave loads required by the Rules by a ship service factor. The details regarding the ship service factor applicable to ships operating nearshore can be found in Ch 2, 1.2 Ship service factor.

1.1.4 Where liquefied gas cargo is carried in the cargo containment systems of a nearshore unit operating in a benign environment, the ship service factors in accordance with Table 2.1.1 Ship service factor for nearshore units can also be applied to the accelerations used for dynamic liquid pressure calculation where vertical accelerations do not include the components due to static weight.

1.2.2 For a permanent installation with a Protected waters service notation, sufficient supporting information and evidence are to be submitted when applying the ship service factor to derive the maximum significant wave height. The maximum significant wave height is to be 3,5 m or less. The significant wave height, H_s, is to be taken from the return period specified in Ch 2, 1.3 Direct calculations 1.3.4. Wave transformation at the terminal due to coastal features shall be taken into account for the maximum significant wave height.

1.2.3 The ship service factor in Table 2.1.1 Ship service factor for nearshore units may not apply to ships where Rule length is less than 100 m or to ships of a novel design such as ships with unusual weight distribution or hull configuration. Such cases are to be discussed with LR at the earliest opportunity.

1.2.4 A larger service factor than in Table 2.1.1 Ship service factor for nearshore units is to be considered when the nearshore unit will operate in close proximity to other large structures. The conditions and details can be found in Ch 2, 1.3 Direct calculations 1.3.7.(a).

1.3.1 If direct calculations are employed for the derivation of design loads, the method in accordance with Ch 1, 4 Load response analysis in the ShipRight Procedure for Ship Units is to be applied for the short-term/long-term value calculations based on the target return periods. All the direct calculations and the detailed methodology are to be submitted for examination.

1.3.2 The hull girder wave loads, motions and accelerations, where required, are to be derived in place of Rule values for the purpose of local scantlings. In no case should the design loads from direct calculations be less than 50 per cent of the 25-year return period dynamic loads defined for unrestricted worldwide transit service.

1.3.3 For strength assessment purposes, design loads in the required ShipRight Strength Design Assessment Procedure can be obtained by direct calculations, if required.

1.3.5 Site-specific metocean or wave scatter data should be submitted for review prior to its use for the design load calculations of on-site operation. The wave scatter data of the Owner-defined transit route may be used for the transit analysis.

1.3.6 Long-term values are to be derived based on the target return period. The long-term values of site-specific operation are to be obtained without the effect of the mooring system. The heading probabilities shall be taken into account instead of equal heading probabilities, where applicable. In general, short-term analysis is performed for transit/towing analysis.

1.3.8 Shallow water depth may transform the waves and vessel motions. Hydrodynamic analysis for the site-specific condition is to be carried out at the most unfavourable water depth in consideration of the tidal variation, including the shallow water effects.