A 1.5t head weight is mounted on top of a number of 5m long steel barrels that are filled with plastic tubes (diameter 95 mm) attached to the barrels by a core catcher. A trigger arm is attached to the head weight, connected by a wire to a small 1m long trigger core extending to just beyond the end of the core barrel. When the trigger core penetrates the sea floor, the head weight is released and the piston produces a weak vacuum in the tube which causes the sediment being cored to enter and move up the tube without disturbing the sediment layers. When the corer returns on deck the plastic tubes are extruded and cut into 1m long sections. |