Surface Telemetry Engineering Mooring (STEM)

Abstract

A Surface Telemetery Engineering Mooring (STEM) has been developed to collect and transmit oceanographic and meteorological data via satellite links. Data telemetered included currents (from 5 0 and 250 meters), water and air temperature, wind, relative humidity, barometric pressure, and various engineering parametersThe unique aspect of the STEM design was the use of electromechanical cable for both the strength member of the mooring and the electrical connection between the subsurface instruments and the surface buoy.The surface mooring was deployed 150 miles south of Cape Cod in 2700 meters of water setout in November 1987 and retrieved in May 1988, it operated successfully through the harsh N. Atlantic winter. OBJECTIVESThe purpose of the Surface Telemetry Engineering Mooring (STEM) was to demonstrate the feasibility of collecting and transmitting data via satellite telemetry. STEM is designed to handle an extensive suite of meteorological, oceanographic and engineering data obtained from sensors distributed on the surface buoy and on the mooring line. The surface mooring was to be deployed well off-shore in deep waters and had to survive the harsh environment of the wintry Northwest Atlantic.This ambitious goal required both electrical and mechanical engineering support. The electrical engineering effort placed emphasis on the modification and integration of existing instruments and sensors with a system controller. This controller ensures the timely and sequential interrogation of the sensors and the subsequent data processing and transfer to buoy mounted, satellite transmitters. The innovative mechanical engineering contribution consisted mainly of the development and evaluation of electromechanical cables which would maintain the buoy on station and would also provide a reliable signal path between the deep sensors and the surface. The mechanical and electrical problems of properly connecting these cables at the buoy attachment point and at the points of instrument insertion in the mooring line also had to be surmounted.The successful completion of the STEM project also depended on advanced buoy engineering for classical mooring design and on specialized mooring logistics for deployment, servicing and recovery. . 0 RETROSPECTIVEThe R/V ENDEAVOR, operated by the University of Rhode Island, deployed the STEM mooring on November 21, 1987 at 39O11N Latitude and 7O0O0W Longitude. This location is near the well-known Site D, 150 miles due south of Cape Cod .( Figure 1). The water depth at the site is 2672 meters. The mooring configuration is depicted in Figure 2 .

ESOM I and II final report

“…The" inhouse" epoxy termination ( Fig. 5) for 3x19 EM cables had been previously during the six month STEM experiment with excellent results (9). The new swage socket termination for the 3x18 EM cables ( Fig.…”

Inductive Telemetry on a Deep Ocean Surface Mooring.

“…In addition to inductive telemetry, programs in acoustic telemetry [2]," [3], [4] and hardwired telemetry systems [5], [6] have been conducted or are presently underway. Examples of all three technologies have been successfully demonstrated in at-sea tests.…”

Performance of sequential decoding of convolutional codes over fully fading ocean acoustic channels

“…One of its goals is to develop and test practical and reliable methods which allow measurements made anywhere in the water column, almost anywhere on the globe, to be telemetered to scientists in the laboratory in near real time (2j. This paper wil describe three technologies The surface mooring problem was addressed in 1987 with the deployment of the Surface Telemetry Mooring (10). This mooring (Figure 1) used a standard, taut wire design in which a length of nylon line provides the compliance needed to keep the mooring taut under a wide range of current and surface conditions.…”