Section 9 Mooring structure

9.1.1 General requirements for turret mooring structures are given inPt 3, Ch 13, 3 Turret structures

9.1.2 General requirements for mooring arm structures are given in Pt 3, Ch 13, 4 Mooring arms and towers.

9.1.3 The minimum hull modulus in way of turret areas and other large openings is to satisfy the Rule requirements for longitudinal strength. When the turret is situated within 0,5L amidships, the minimum hull midship section modulus about the transverse neutral axis at deck or keel is to be maintained in way of the turret opening. Increases in plate thicknesses are to take place gradually. Any reduction in hull section modulus should be kept to a minimum and compensation fitted where necessary.

9.1.4 For a turret-moored unit with a turret well opening, suitable precautions are to be taken to prevent damage to the well structure in transit and when disconnected, when applicable.

9.1.5 The hull structure in way of mooring connections is to be verified by direct calculation. In all cases, the structural analysis is to include a representative portion of the hull and tank structure, together with the integration of the mooring system with the unit's structure. The analysis is to be in accordance with the LR ShipRight Procedure for Ship Units and Pt 4, Ch 5 Primary Hull Strength, as applicable.

9.1.6 Continuity of primary structural elements is to be maintained as far as practicable in way of turret openings and mooring support structure.

9.1.7 Turret bearings are to comply with Pt 3, Ch 2 Drilling Units. The turret bearing support structure is to be integrated into the hull structure.