Measurement and control system for deep sea vane-shear device

A vane shear device was developed for in-place measurement of the undrained strength of clays in the marine environment. This device required a measurement of torque applied to a vane as the soil in which the vane was embedded failed in shear and was remolded. The system was designed to operate at depths of 4.5 km and to conduct measurements at depths up to nearly 3 m below the mudline. Control signals to and data from the apparatus were telemetered over a single wire with ground return and the tower was self-powered. Torque measurements required successful use of electrical stain gages and leads exposed to high hydrostatic pressures. The apparatus has been successfully operated at several sites in the Atlantic Ocean and in the Gulf of Mexico at depths of 3635 m.