Sampling devices

Source: BGR

Cable-run piston and gravity corers are capable of obtaining long sediment cores with a diameter of ca. 120 mm and a maximum length of 20 m. In contrast to the gravity corer that is driven into the seafloor sediments purely by its 2 ton weight, the piston corer disposes of a technique that allows free-fall into the sediment, thus generally retrieving longer sediment cores.

Source: BGR

The multicorer is deployed when a large number of intact, short sediment cores (up to 50 cm length), together with the overlying bottom water, are required.

Source: BGR

The box corer allows recovery of up to 50-cm-long, large-volume sediment samples from the seafloor (dimensions 50 x 50 cm).

Source: BGR

The chain-bag dredge is dragged over the seafloor in order, e.g., to collect large quantities of manganese nodules or hard rocks from the seabed.

Source: BGR

Very large sample volumes can be obtained selectively from the seafloor using the TV-grab, which has a weight of 2.0 tons. A downward-looking television camera is located centrally between the two grab shovels. The TV-grab is lowered with the shovels in an open position until the seafloor is clearly visible. Using the winch, the TV-grab is held at an adequate distance from the seafloor whilst the ship moves forward at low speed – this process allowing the camera-supported search for interesting sampling locations. As soon as a suitable sampling location has been spotted on the monitor, fast reaction and accuracy are required to lower the TV-grab onto the seafloor, which in turn triggers the closure of the two shovels with a pressure of ca. one ton. The large closing force also allows the TV-grab to “bite” into consolidated rocks.