A marine pipeline installation vessel for laying an offshore rigid pipeline in the sea, onto the seabed, said vessel at least being adapted to carry out the rigid reel lay method, wherein the vessel comprises: • a hull and a deck; • at least one vertical storage reel (10; 16) for the storage of a spooled rigid pipeline to be laid, which storage reel is rotatable about a horizontal reel axis; the storage reel (10; 16) comprising: ∘ a left and right vertical flange (12a, 12b; 13a,13b) between which a hub (14;15) extends, ∘ a hub (14; 15) onto which multiple layers, each comprising several windings of pipeline can be stored; • a left and right reel support structure (30; 31) adapted to support the weight of the at least one storage reel, defining the horizontal reel axis, which left and right support structures are supported by the vessel, • a storage reel drive (40; 41) to rotate the storage reel; • a pipeline launch assembly mounted to the vessel downstream of the reel in the direction of unspooling, which pipeline launch assembly is adapted to launch the unwound pipeline in a firing line into the sea, comprising a pipeline guide having an elongated pipeline guide member orientated essentially in the direction of the storage reel and providing an essentially circular or semi-circular pipeline guide surface, which pipeline guide is adapted to guide unwounded pipeline from the storage reel over the pipeline guide into the firing line, wherein said pipeline contacts the pipeline guide member at a guide contact point upstream of the firing line and departs said member at a guide departure point into the firing line; ∘ wherein a left and right fleet angle (LFA; RFA) of a storage reel are defined as the angle between a first line drawn from the guide departure point to the storage reel, perpendicular to the reel axis, and a second line drawn from the guide departure point to the left and right flange, respectively, • a straightener provided downstream of the storage reel in the direction of unspooling to provide straightening to the rigid pipeline, • at least one tensioner provided downstream of the pipeline guide which is adapted for engaging the pipeline in the firing line and supporting at least part of the weight of the launched pipeline to control the rate of laying of the rigid pipeline on the seabed, • a pipeline support device adapted to support the weight of the launched pipeline in the firing line; characterized in that the left and right support structures (30; 31) are embodied to form a pivoting structure allowing an angular adjustment of the horizontal reel axis about a vertical axis to alter the angular position of the at least one storage reel (10; 16), and wherein at least one support structure drive is provided to controllably adjust the angular position about said vertical axis. • a hull and a deck; • at least one vertical storage reel (10; 16) for the storage of a spooled rigid pipeline to be laid, which storage reel is rotatable about a horizontal reel axis; the storage reel (10; 16) comprising: ∘ a left and right vertical flange (12a, 12b; 13a,13b) between which a hub (14;15) extends, ∘ a hub (14; 15) onto which multiple layers, each comprising several windings of pipeline can be stored; ∘ a left and right vertical flange (12a, 12b; 13a,13b) between which a hub (14;15) extends, ∘ a hub (14; 15) onto which multiple layers, each comprising several windings of pipeline can be stored; • a left and right reel support structure (30; 31) adapted to support the weight of the at least one storage reel, defining the horizontal reel axis, which left and right support structures are supported by the vessel, • a storage reel drive (40; 41) to rotate the storage reel; • a pipeline launch assembly mounted to the vessel downstream of the reel in the direction of unspooling, which pipeline launch assembly is adapted to launch the unwound pipeline in a firing line into the sea, comprising a pipeline guide having an elongated pipeline guide member orientated essentially in the direction of the storage reel and providing an essentially circular or semi-circular pipeline guide surface, which pipeline guide is adapted to guide unwounded pipeline from the storage reel over the pipeline guide into the firing line, wherein said pipeline contacts the pipeline guide member at a guide contact point upstream of the firing line and departs said member at a guide departure point into the firing line; ∘ wherein a left and right fleet angle (LFA; RFA) of a storage reel are defined as the angle between a first line drawn from the guide departure point to the storage reel, perpendicular to the reel axis, and a second line drawn from the guide departure point to the left and right flange, respectively, ∘ wherein a left and right fleet angle (LFA; RFA) of a storage reel are defined as the angle between a first line drawn from the guide departure point to the storage reel, perpendicular to the reel axis, and a second line drawn from the guide departure point to the left and right flange, respectively, • a straightener provided downstream of the storage reel in the direction of unspooling to provide straightening to the rigid pipeline, • at least one tensioner provided downstream of the pipeline guide which is adapted for engaging the pipeline in the firing line and supporting at least part of the weight of the launched pipeline to control the rate of laying of the rigid pipeline on the seabed, • a pipeline support device adapted to support the weight of the launched pipeline in the firing line;