In situ vane system for seafloor strength investigations

The In Situ Vane (ISV) system has been developed to determine the strength profile within the upper 1.5 m of deep sea clays. The system is designed to operate in 6000-m water depth after one-year dormancy on the bottom and consists of four integrated packages; controller and data acquisition system, mechanical system, volume compensator, and power supply. This paper describes development of a prototype which was used under a pressure of 550 bars after a 30-day dormancy and of the full system which was successfully used in a deep water (5800 m) test. In the first full application of the system the ISV will be used to measure changes in sediment strength caused by high temperature (300degC) as part of the U.S. Subseabed Disposal Program.