You can vary how far the corer penetrates into the sediment by selecting one or two of the rings furthest down on the corer. The corer is lowered until it is 0.5-1m above the sediment surface, when pause for about 10 seconds to allow the corer to stop oscillating and/or rotating. The corer is lowered until a light tug on the cable is felt, when the closing mechanism is released. When the corer is pulled up, the piston needs to be put in the bottom of the tube before lifting it out of the water. The tube is then removed from the corer and placed with the piston on the extruder rod. By releasing the lock you can easily evacuate superfluous water at the top and manually move the core tube downwards until the sediment-water interface is a few centimeters below the top of the tube. Then the lock is fixed and you can attach the the scraper platform on the top of tube. Samples are pressed out by turning the extruder's bottom, one turn 360° = 5 mm. Scrape the samples into a suitable container.
The principal is identical between the two versions, only the tube diameter differs. The 90 mm corer has a tube with 90 mm outer diameter. The samples collected is larger compared to the 70 mm corer. Both corers come with 50 cm long tubes as standard, but tubes can be tailored up to one meter. The samples are effectively 40 centimeters as a maximum, with the standard tube.