For a spar type floating platform having risers passing vertically through the center well of a spar hull, there is provided apparatus for supporting the risers from a gimbaled table supported above the top of the spar hull. A lock ring engages with an accommodating groove of a socket. A plurality of additional clamp collars are arranged to surround a part cylindrical portion of the channel members to bridge between panels and to form a local clamping force on the channel member. Suitable adhesives can include one-, two- or multipart adhesives.