Design, Manufacture, and Deployment of Buoyant Cables in Underwater Applications

Abstract

Strong, but thin, optical cables are a key component for many underwater applications such as ROVs, sensing systems and many DoD weapons systems. Strength members used in cable constructions are materials such as extruded Liquid Crystal Polymers (LCP) and aramid yarn.The cable may need to have controlled specific gravity (SG) so that it can float, sink or be suspended in the water column. Therefore, cable design must allow for easy manufacturing and customization to meet the SG needs of the application in long lengths.Deployment from a moving platform may require the cable to be provided in a precision wound pack of several km length appropriate for the application. Precision winding of fiber optic cables allows for rapid deployment without a spinning spool of cable requiring a fiber optic rotary joint. This configuration of cable also prevents any spool momentum that would be generated by a large spinning spool of cable. In the case of a precision wound spool, the fiber can be deployed at variable speed without running the risk of extra cable being deployed and potentially hockling the fiber optic cable.In many applications the cable is used as a communication link between discrete nodes deployed in the open ocean environment where the span can stretch from meters to miles. The cable may need to survive the constant pull and push of changing currents for days or even months. In this situation it is important to understand the dynamic strength but also the static strength of the cables.Linden has developed a family of optical cables that are thin but strong, therefore, appropriate for the above applications (STFOC). The designs allow easy customization and control of SG and manufacture of 50 km continuous lengths. We have also developed methods to generate precision wound packs that are many km in length.In this presentation we will discuss some of the considerations that go into the design and manufacture of precision wound cable packs for use in underwater applications.