The present invention relates to a method for operating a drilling vessel adapted to run large diameters surface casing joints having a diameter of over 20 inch (51 cm) and a length of 30-50 feet (9-15 meters), and build a surface casing string. According to the invention three or more surface casing joints are interconnected into pre-assembled surface casing stands having a length of over 100 feet (30 meters). These surface casing stands are substantially horizontally stored and transferred by a casing stand handling system to a surface casing string handling capacity hoisting device, which subsequently lowers the surface casing string.