PURPOSE: To remote control various operations of PLEM value by arranging hydraulic pressure generator, hydralic pressure storing device, and various king of valves on a buoy moored on the surface of the sea while coupling through an operating hose with valves for PLEM placed on the bottom of sea.

CONSTITUTION: In a one-point mooring buoy for loading/unloading liquid between a tanker and an on-short oil storage facility while mooring a buoy 1 on the surface of the sea and placing PLEM4 at the bottom of the sea, a compressed air tank 5, hydraulic pump 7, pressure storage tank 8, valve 9, etc. are arranged on the buoy 1. The buoy 1 is coupled through an operating hose 15 with g gate valve 16 and an operational section 17 of PLEM4 to remote control a valve 6 of PLEM4 through operation of the valve 9. Consequently the opening/ closing work of PLEM valve at the bottom of the sea performed conventionally by a diver can be eliminated.