Prediction and measurement of the stability of a deep-sea trimooring

The three-dimensional array of current velocity and temperature sensors for the Internal Wave Experiment (IWEX) was supported on a tripod mooring rising from the sea floor to a height of 5 km in water km deep. The mooring was so designed that its current-induced motions would be small, as required by the experiment. Sensitivity of the mooring excursions to cable buoyancy, leg inclination, apex buoyancy and cable size was examined by computer simulation to optimize the design.When deployed the mooring carried nine precision pressure recorders to monitor its configuration and stability. After removal of the tidal pressure variations, the pressure records confirmed vertical excursions small enough to contribute only insignificant noise to the velocity measurements. Comparison of the measured excursions with those predicted by computer simulation using actual current measurements showed good agreement.