Accession Number : ADP003830

Title :   Roll Damping at Forward Speed,


Personal Author(s) : Abkowitz,M. A.

Report Date : AUG 1983

Pagination or Media Count : 14

Abstract : Three dimensional body theories indicate a significant effect of forward speed on the linear roll damping coefficient, whereas two dimensional and strip-slender body theories indicate that the effect is small. Model tests, carried out many years ago, demonstrated a strong effect of forward speed on the roll damping of a battleship. The three dimensional body theories indicate a significant reduction in damping at pitch resonant frequencies and a significant increase in damping at roll resonant frequencies. Forced rolling tests on a model of the MARINER at various forward speeds have been carried out in the MIT Ship Model Towing Tank to measure the effect of forward speed on roll damping. The results confirm the three dimensional theory trend. Ability to closely estimate the roll damping at ship speeds will improve seakeeping motion prediction and improve operational procedures with respect to efficiency and safety. (Author)

Descriptors :   *Ship motion, *Roll, Damping, Coefficients, Velocity, Theory, Three dimensional, Ship hulls, Pitch(Motion), Resonant frequency, Ship models, Dynamic response, Water waves, Seakeeping, Mathematical models, Model tests

Distribution Statement : APPROVED FOR PUBLIC RELEASE