Abstract: Disclosed are a method and apparatus for laying a submergible elongate structure upon the bed of a body of water. The last-assembled portion of the structure is supported upon a floating vessel having a deck which defines a path for movement of the structure relative to the deck, the path including an assembly region in which additional submergible elongate structure can be assembled from components. The structure is clamped downstream (relative to the path of movement) of the assembly region and then additional submergible elongate structure is assembled in that region and is secured to the previously existing structure. The free end of the additional structure is gripped with a connector that is connected, through a flexible cable under tension, to a winch. Then the clamping assembly is disengaged from the structure so that the winch alone maintains tension on the structure.