Development and Evaluation of a Motion Compensating Lift System for Deep Ocean Construction.
Abstract
A system to raise and lower loads in the deep ocean while providing lift-line tension control and payload motion control was designed, fabricated, and tested. Design parameters included a maximum wet payload weight of 40,000 pounds at a maximum operating depth of 6,000 feet through sea conditions state 4 when the system is mounted on an ARS-type vessel. A load-handling system of this type allows soft landing of a payload on the seafloor. In addition, the reduction in the dynamic tensions in the lift line allows the use of smaller lines for a given payload weight, greater payload capacity for a specified line size, or a greater depth capability for a given line size. The concept selected for development called a'boom bobber' incorporated a boom pivoted at one end and supported by a relatively soft passive fluid spring. This spring decouples the payload from the motion of the support platform. At-sea testing included determination of system performance for two-payloads of 12,000 and 40,000 pounds wet weight. Cable tensions and time-correlated motions of the ship, lift system, and payload were recorded. Data obtained were sufficient to prove the promise of the basic concept.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1975
- Accession Number
- ADA019027
Entities
People
- L. W. Hallanger
- R. L. Brackett
Organizations
- Naval Facilities Engineering Service Center