Spar construction method

Method of constructing a floating structure comprising an elongate floating body (1) and a deck structure (2) connected to the upper end (3) of the floating body (1) comprising the steps of:

• providing the elongate body,
• providing the deck structure, wherein the deck structure and the elongate body are each provided with coupling means (4, 12) for connecting the elongate body and the deck structure,
• transporting the elongate body to its mooring site,
• transporting the deck structure on a buoyancy member to the mooring site,
• ballasting the elongate body such that it is in its vertically upright position,
• positioning the elongate body below the deck structure, and
• raising the elongate body by deballasting it,
• wherein the elongate body comprises an elongate buoy for oil production and storage and comprising storage and ballast tanks, and having at its bottom ballast material (6) which is retained upon placing the buoy in its upright position, the deck structure and the elongate body during transport being coupled via control lines (15), the control lines (15) being connected between the deck structure (2) and the floating body (1) for control of the ballasting of the elongate body by supply or removal of water to the ballast tanks during transportation of the elongate body, erection and operation, the control lines (15) remaining attached between the deck and body after erecting of the elongate body, the elongate body being free from external buoyancy members prior to erecting said body.