Offshore vessel (1,150) comprising a hull (2,155) with a length of at least 250m and a width of at least 30 m, a bottom, longitudinal sides (5,6;153,154), a bow (3,151) and a stern (4,152), spread mooring connectors (9,10,12,13;156,157,158) situated at each side of the hull near the bow and near the stern on the longitudinal sides, near deck level, and a riser moonpool (17,170) situated on a longitudinal center line of the vessel extending in a vertical direction from deck level to keel level, the moonpool comprising a riser connector member for attaching risers (27,76,76',77,77'), to the hull (2,155), wherein the moonpool is situated closer to the bow (3,51) than to a mid-ship position, wherein the moonpool comprises a vertical wall forming a closed casing of circular or square cross section and is adapted to accommodate risers, an internal turret or hydrocarbons or water, wherein the vessel does not comprise mooring means at or near the bottom in the area of the moonpool, and wherein at least one landing zone is provided for mooring a work-over or supply vessel along one or along each longitudinal side (5,6;153,154) near the rear and/or front spread mooring connectors (9,10,12) the offshore vessel being provided with a lifting device (176, 176') on deck near the at least one landing zone, wherein the riser connector member comprises a riser support structure extending across the moonpool (17,170) and placed in a fixed position and orientation in the moonpool near the bottom, for attaching the risers (27,76,76',77,77') at spaced-apart positions distributed over the cross section of the moonpool, wherein at least one manifold module (68,69) is situated in a manifold area (33,34) that is defined by the longitudinal sides (5,6;153,154) of the vessel and a front and rear transverse region (35,36) that is situated within 20 m, preferably within 10 m and more preferably within 1 m from a respective front and rear position (39,42) of the moonpool (17,170), and a pulling system (70, 121,172) is situated near deck level in an area at or near the moonpool, and comprises a movable lifting member (103,105,111) that is displaceable across the moonpool (17,170) for attaching to the risers (27,76,76',77,77') and exerting an upward pulling force on the risers. the moonpool comprising a riser connector member for attaching risers (27,76,76',77,77'), to the hull (2,155), wherein the moonpool is situated closer to the bow (3,51) than to a mid-ship position, wherein the moonpool comprises a vertical wall forming a closed casing of circular or square cross section and is adapted to accommodate risers, an internal turret or hydrocarbons or water, wherein the vessel does not comprise mooring means at or near the bottom in the area of the moonpool, and wherein at least one landing zone is provided for mooring a work-over or supply vessel along one or along each longitudinal side (5,6;153,154) near the rear and/or front spread mooring connectors (9,10,12) the offshore vessel being provided with a lifting device (176, 176') on deck near the at least one landing zone, wherein the riser connector member comprises a riser support structure extending across the moonpool (17,170) and placed in a fixed position and orientation in the moonpool near the bottom, for attaching the risers (27,76,76',77,77') at spaced-apart positions distributed over the cross section of the moonpool, wherein at least one manifold module (68,69) is situated in a manifold area (33,34) that is defined by the longitudinal sides (5,6;153,154) of the vessel and a front and rear transverse region (35,36) that is situated within 20 m, preferably within 10 m and more preferably within 1 m from a respective front and rear position (39,42) of the moonpool (17,170), and a pulling system (70, 121,172) is situated near deck level in an area at or near the moonpool, and comprises a movable lifting member (103,105,111) that is displaceable across the moonpool (17,170) for attaching to the risers (27,76,76',77,77') and exerting an upward pulling force on the risers.