GD131/21 SOUTH CHINA SEA UNDER WATER ENGINEERING WORK BY M/V “HUA TIAN LONG”“NAN TIAN LONG”“NAN HAI JIU 101” “DE JU” “DE CHENG” “DE SHUN” IN AREA WITHIN 1KM RADIUS OF 21-15-50.8N 111-38-48.9E FROM 20 JUN TO 31 JUL. SIGNAL LIGHTS AND SHAPES WILL BE EXHIBITED ADVISED TO AVOID GUANGDONG MSA CHINA