Angel Descent

The need for accurate and undisturbed core samples has led to the development of this new coring method with controlled penetration speed, in order to obtain sediment samples with more accurate outcomes.

Based on the water depth, this methodology, called “Angel Descent“, can be applied in different ways: in shallow water the corer is connected to a winch or a crane with variable speed control, while the piston is tied off to a fixed point on board with a very resistant rope; this rope runs down the length of the corer and attaches to the top of the piston. The configuration of the Carma® Piston Corer has three variable components: the weight of the corer head, the length of the corer tube and the configuration of the active piston. In shallow water, other variables do not need to be considered: the elasticity of the cable is insignificant and the height of the free fall -along with the slack- do not come into play when using this new methodology.

For deep waters has been designed a special winch: Carma® Winch. This instrument, connected to the main cable, located just above the trigger, will allow the penetration speed to be controlled. The configuration variations of the corer would remain more or less unchanged, given that the height of the free fall will be set to zero, as will the slack. The elasticity of the cable will not, however, be insignificant, but this problem can finally be solved. Usually, the cable snaps back once released, after it stretches out due to the weight it sustains, depending on the depth of the job at hand. With this new method, the problem is solved because the mass of the corer – which weighs on the main cable – gradually, declines: the speed of the backlash of the main cable will be less than the speed of penetration of the coring tube in the seabed, thus allowing a much better result to be obtained.

The method of controlled penetration speed can also be used in geotechnical or environmental studies, for example in the dating of undisturbed samples for determining the time-line of human affected events when dealing with environmental issues such as contamination and pollution.

Angel Descent - Italian Harbour

Angel Descent

Case History