The square box (500x500x600 mm) is fixed to a head with a column that are connected to a frame by a cardanic suspension. This allows vertical penetration of the box into the sediment. A crank with spade including rubber sealed plate is attached to the head of the box. The column is filled with lead weights to aid penetration. During lowering to the sea floor and sampling, flaps at the top of the head remain open to allow a free flow of water. This prevents pressure build-up and following disturbance of the sediment surface. When the box has reached the sea floor, the box is triggered by a trip as the column passes through its frame. While pulling the corer out of the sediment the flaps at the head are closed and the spade is drawn into vertical position so that the bottom of the box is closed and the sample is secured. Once the box returned onboard, the box can be detached from the frame for subsampling of the sediment surface. Some square box are equipped with a removable front plate to obtain a undisturbed section of the near-surface sediments. |