Electro-Mechanical (EM) and Electro-Optical-Mechanical (EOM) cables are used in the upper ocean for buoy moorings, instrument towing, and payload lifting purposes. They are subjected to slack-snap conditions, flexing, and strong dynamic peak-loads due to surface wave forcing. Lightweight designs use a strength member of high performance or industrial synthetic fibers. The established cable constructions use a conductor core and external strength member package. Alternative designs position the conductors around a strength member core. Stretch mechanics and cyclic tension fatigue tests show that the alternative designs can keep the conductors within their narrow elongation limits, while the traditional designs overextend their conductor package.
There is an expanding need for conductor linkage through working cables between submerged underwater sensors, instruments, or ROVs, and surface buoys or service ships. The working cables are used for mooring, lifting, or towing purposes. These cables have to endure in the dynamic and highly fatiguing upper ocean environment with sudden slack conditions followed by shock-like snap loading. In addition the cables experience continuous flexing in particular near the attachment points to surface buoys due to the buoys' roll and pitch in surface waves. Electrical conductors and increasingly optical light guides have to be incorporated into suitable cable designs together with a strength member. The term "lightweight cable "refers to a cable with a nonmetalic strength member made from "conventional" industrial or, in most cases, high performance synthetic fibers I The term "lightweight upper ocean working cables'" describes electrical and optical cables for upper ocean applications, which are constructed with synthetic fiber strength members 2. The purpose of this paper is to provide design guidelines that result in constructions with low stress survivable conductor paths by utilizing the basic stretch mechanic s of Lightweight Upper Ocean Working Cables.
