Accession Number : ADB068225

Title :   An Assessment of State-of-the-Art Methods for Calculating Current Loads on Moored Ships.

Descriptive Note : Technical note,

Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA

Personal Author(s) : Palo,P. ; Owens,R.

Report Date : JUN 1982

Pagination or Media Count : 37

Abstract : This report presents an examination of techniques for computing current-induced forces and yaw moment on moored vessels based on experimental data or procedures from nine independent sources. No validated full-scale data were located, so only relative evaluations were possible. For the lateral and longitudinal current forces, the none sources were applied directly (or scaled) to two representative hull types. This comparison shows extreme differences among the nine methods. It is concluded, based on these differences that the present uncertainty in these state-of-the-art current force predictive methods is + or - 80% for head currents (longitudinal force) and + or - 50% for beam currents (lateral force). Comparisons are also presented for the current-induced yaw moment and water depth (blockage) correction factor. The differences among these latter two are even greater than those for the lateral and longitudinal forces. The Navy's DM-26 approach was found to be inconsistent and can be in error by a factor of 5; the latest draft (90%) of the ongoing revision of that manual (DM 216.6) was considered acceptable except for the longitudinal forces. Because of uncertainties in the scaling criteria, full-scale measurements are recommended to allow proper evaluation of these various methods. (Author)

Descriptors :   *MOORING, SHIPS, OCEAN CURRENTS, LOADS(FORCES), YAW, MOMENTS, COMPUTATIONS

Subject Categories : Physical and Dynamic Oceanography
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE