At-Sea Handling And Motion Compensation

The motion of a vessel in all but the calmest of seas can put severe restraints on most operations. In particular, the handling of submersibles, RDVS, and oceanographic instrumentation has generally been limited to a sea state 2, maximum. This paper considers the use of a launch/recovery motion compensated crane for handling various systems, by comparing it to alternative approaches and by presenting performance data for a passive crane. The use of a compensated crane can readily extend operations to sea state 5 and greatly improve safety and data quality. Several such systems have been built and are in operation with proven reliability and ease of use. The units are specifically designed for use on smaller vessels where efficiency of function, flexibility of use, and minimum size and weight are not only desirable, but necessary.