Self deployable deep sea moorings

Abstract

As part of a development effort in the field of moored arrays sponsored by the Office of Naval Technology, the Ocean Structures and Moorings Laboratory (OSM&L), Applied Ocean Physics and Engineering Department (AOP&E), Woods Hole Oceanographic Institution (WHOI) conducted a study in 1991 to assess the feasibility and the merits of several self-deployable mooring designs. This study included a brief review of the state of the art, the performance of lab tests to evaluate different mooring line payout concepts, and the preliminary design of a typical candidate mooring. The results of this study are presented in this report. The report first reviews three types of single point moored arrays which are amenable to self-deployment: subsurface, subsurface with surface expression, and surface with bottom inverted catenary. It then describes the features common to all self-deploying moorings: techniques for line and instrument storage, means for controlled payout, bottom finders and lock up mechanisms, and it also outlines desirable specifications for sensor sizes, cables and connectors. Next the report reviews typical deployment scenarios from the bottom up or from the surface down as they apply to the three types of moorings retained. In its final section, the report presents the conceptual design of a 6000 meters depth capability, bottom up deployment, candidate mooring. This configuration should be of strong interest when contemplating the deployment of a large number of identical subsurface moorings, interconnected by a bottom cable, and in "close" proximity to one another. The case study outlines the design objectives and the current profiles, specifies the main components, evaluates their performance with the help of a standard computer program, and presents packaging and payout control details. Finally, a plan is proposed for the controlled, in-situ evaluation of a prototype.