A pipeline laying ship and an improved method of laying a pipeline in a marine environment is disclosed. The pipeline laying ship is a dynamically positioned barge or self-propelled dynamically positioned vessel with a hull having a deck area that supports a pair of reels. The reels are independently rotatable, and are position to generally port and starboard relative to one another. A pipe joint storage area is provided for containing multiple joints of pipe. One or more pipeline welding stations are provided on the deck next to the reels, the pipeline welding stations being positioned to join the joints of pipe together to form an elongated pipeline that can be wound upon a selected reel of said pair of reels. A tower is provided for guiding the elongated pipeline as it is unwound from a selected reel, the tower including at least a bend controller, a straightener and a tensioner. The tower is transversely and movably mounted upon the hull between the port and starboard positions that enable a pipeline to be welded and then wound upon either of the reels and to be unwound from either of the reels for launching to the sea bed via the tower. The tower can be mounted upon a transverse track. The tower can be positioned aft for launching the pipeline from the hull stern. The tower can be mounted amidships for launching the pipeline through a vertical hull opening or "moon pool". A specially configured clamp is mounted on the hull below the top of the tower for clamping and holding the pipeline as it is launched from the tower to the water's surface. The clamp can be moved with a section of the clamped pipeline between port and starboard positions enabling other pipe sections (e.g. manifolds) to be welded to the pipeline above the clamp.