Gravity drop and piston corers

Gravity corers provide a rapid means of obtaining a continuous core sample in water depths down to several thousand metres. Depending upon their deployment and operating systems, gravity corers can be deployed from a wide range of vessels. A gravity corer consists of a steel tube in which is inserted a plastic liner to retain the core sample. The penetrating end of the tube is fitted with a cutter and a concave spring-steel core-catcher to retain the sample when the corer is retracted from the soil and recovered to the ship. One of the simplest geotechnical devices, the impetus of gravity acting on the heavy, freefalling device is the motive force that drives the corer into the soil.