Accession Number : ADA019027

Title :   Development and Evaluation of a Motion Compensating Lift System for Deep Ocean Construction.

Descriptive Note : Final technical rept. Jul 69-Oct 74,


Personal Author(s) : Hallanger,L. W. ; Brackett,R. L.

Report Date : DEC 1975

Pagination or Media Count : 36

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.

Descriptors :   *Naval vessels, *Cranes, *Construction equipment, Shipboard, Ship motion, Deep oceans, Construction, Lift, Mechanical cables, Ocean bottom, Payload, Tension, Reduction

Subject Categories : Construction Equipment, Materials & Supplies
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE