Duplex yoke mooring system

Abstract

An offshore offloading system for hydrocarbon products from a storage station such as an LNG/FPSO to a shuttle vessel. The system includes a yoke mooring arrangement having a yoke and a connection assembly. One end of the yoke is selectively disconnectable to the shuttle vessel, while the other end of the yoke is rotatably connected to an end of the connection assembly which has its other end rotatably connected to a frame which extends from an end of the storage station. The yoke and connection assembly are arranged such that a transverse force in the lateral or y-direction moves the end of the yoke less than twice the movement of the yoke in response to an x-direction force. The system also includes arrangements for providing a hydrocarbon fluid flow path from the storage station to the shuttle vessel when the shuttle vessel is disconnectably moored to the storage station. A first fluid flow path arrangement includes a crane/boom arrangement mounted on a frame extension of the storage station so that a crane slewing arc radius of the transfer system is not larger than one half the separation distance between the storage station and a forward perpendicular of the shuttle vessel. A second arrangement includes a fixed frame with a piping pantograph mount at its end. A trolley and service platform suspended therefrom move between an operational position away from the pantograph and a service position beneath the pantograph when it is folded into a storage position.