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Restrained model tests in head seas

Date

1959-03

Authors

Schulz, Edmund F., author
Colorado State University, Civil Engineering Section, publisher

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Abstract

This report presents the experimental forces and moments acting on a five-foot model tanker when it was towed in head seas. All the motions of the model except uniform forward translation were restrained. The model was towed in two wavelengths - approximately one-half the model length and approximately equal-to model length. Three pressure gages were mounted in bottom along the keel to measure the attenuated wave pressure. The forces and moments were divided into steady state and oscillatory forces and moments. The steady-state heaving force was independent of wave configuration and increased with increasing speed. The steady-state pitching moment was nearly independent of speed, but was strongly dependent upon wave configuration. The steady-state drag force was largely independent of wave configuration, but exhibited a complex variation with speed. The oscillatory heaving force and pitching moment increased with increasing relative wavelength and speed. The oscillatory drag force was independent of wavelength and increased with speed up to Fr = O.2; it then decreased with further increase in speed. The greatest part of the -nave attenuation occurred under the fore-body. At zero speed of advance the model more effectively attenuated the shorter waves. The attenuation factor decreased with increasing speed in head seas. At higher speeds of advance the model more effectively attenuated the larger waves.

Description

CER59EFS7.
March 1959.
Includes bibliographical references (page 14).
Prepared for David Taylor Model Basin, Department of the Navy, through the Colorado State University Research Foundation.

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Subject

Ships -- Maneuverability -- Testing
Ship handling
Navigation -- Testing
Wavelets (Mathematics)

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