The Effect of Moving Weights on Ship Roll Motions

Gharechahi, Ataollah; Shafizadeh, Esmaeil

doi:10.22113/jmst.2015.12027

The Effect of Moving Weights on Ship Roll Motions

Document Type : Original Manuscript

Authors

Ataollah Gharechahi

Esmaeil Shafizadeh

Department of Shipbuilding, Faculty of marine engineering, Chabahar Maritime University, Chabahar, Iran.

10.22113/jmst.2015.12027

Abstract

In this research, the effect of weights that lose their lashing systems and can move freely in line with vessel breadths is investigated on ship roll motions. Therefore, the effect of friction and possible barriers that impeded on free movement of weights are neglected.
To study the effects; weights with different masses are hung on pendulum which is installed on an ocean going trawler model and vessel roll motions is being experimentally tested.
The results show that whoever hanging weights can increase the center of gravity of vessel and decrease the vessel stability; but caused increase the period of roll motions. The findings of research also can be used in design of damping systems of roll motions.
In addition, the experimental results are compared with numerical results based on the Strip Theory. The results show that the damping coefficient has important role in the accuracy of numerical results.

Keywords

MOVING WEIGHTS

SHIP ROLL MOTIONS

SHIP ROLL MOTION PERIOD

STRIP THEORY

20.1001.1.20088965.1400.20.2.3.5

Subjects

مهندسی اقیانوسی

Biran A. B., “ Ship Hydrostatics and Stability” , 2014, Second Edition, Butterworth-Heinemann.

Bentley Systems Incorporated, 2013, "Maxsurf Motions Windows Version 20 Program & User Manual".

Housner, G.W., Bergman, L.A., Caughey, 1997, T.K., Chassiakos, A.G., Clause, R.O., Masri, S.F., Skelton, R.E., Soong, T.T., Spencer, B.F., Yao, J.T.P., “Structural Control; Past, Present, and Future”, Journal of Engineering Mechanics 123(9).

IMO, Annex 2, Resolution Msc.267(85), 2008, " Adoption of the International Code on Intact Stability".

Inoue, R., Kanyama, T., Kanaji, H., 1994,"Vibration Control of Existing Buildings Under Motion Excited by Moving Vehicles", Proc. of First World Conference on Structural Control 2.

Koike, Y., Tanida, K., Mutaguchi, M., Murata, T., Imazeki, M., Hiroshige, E., 1997, “Development of hybrid anti-rolling device for ships and test at sea”, Recent Progress on Science and Technology IHI, 6, 20–26.

Tamura, Y., Fujii, K., Ohatsuki, T., 1995, Wakaham, T., Koshaka, R., "Effectiveness of Tuned Liquid Dampers Under Wind Excitations", Engineering Structures 17.

Thomas W. Treakle III, Dean T. Mook , Stergios I. Liapis, Ali H. Nayfeh, 2000, “A time-domain method to evaluate the use of moving weights to reduce the roll motion of a ship”, Ocean Engineering 27 1321–1343.

Townsin R.L. ,1997 , “Trawler Model NA 8-14 for use with large angle ship stability dynamometer”, School of Marine Technology, University of Newcastle Upen Tyne , England.

http://discoverarmfield.com, “Ships Vibrations Test Model, Ships Stability Apparatus, NA 8 & NA 14”