The downhole cone penetration test (CPT) system of Helms is manufactured and supplied by AP van den Berg, Holland called the WISON-APB Downhole CPT. The system is basically a double acting cylinder with the soil-testing instrument attached to the end of the piston rod. An umbilical is released from a remote-controlled and electrically driven constant tension winch on deck of the geotechnical drilling vessel and provides for 2-way data transfer, electric power and hydraulic power to the tool.
This enables CPT tests to be performed in situ from the base of a borehole either offshore or onshore enabling soil parameters to be measured below the proposed foundation levels. With the current umbilical setup tests can be performed within a total drill string length in excess of 300m. It consists of a downhole jacking unit with a 3m stroke and a thrust capacity of 50 kN and a second unit with a 1m stroke and a thrust capacity of 100kN