A PROBABILISTIC STUDY OF THE SIMULTANEOUS EFFECT OF SHIP MOTIONS ON THE CARGO SHIFTING ONBOARD

Cargo movement aboard ship can occur even in waves that produce only moderate rolling motion. It is caused when the simultaneous effect of vertical acceleration, horizontal acceleration and roll motion on the cargo onboard, defined as the equivalent roll angle, becomes sufficiently large for the problem to develop. In this paper, an analytical expression is derived for the probabilistic calculation of the equivalent roll angle, which has a nonlinear characteristic. Also, a so-called indirect time-domain simulation method is described for calculating the problem. Both methods are based on motion transfer functions calculated according to strip theory. The calculations presented show both methods to be in good agreement. A probabilistic calculation of the equivalent roll angle of a ro/ro ship is carried out using the two methods and focusing on parameters such as significant wave height, mean wave period, ship sped, and relative course angle. It is proved from the point of view of probability that the nonlinearity of equivalent roll angle results in a magnifying effect on its extreme value. The calculation shows also that in severe wave conditions large peak values of equivalent roll greater than 35 deg can be expected by the studied ro/ro ship.

• Supplemental Notes:
  • Marine Technology, v 33 n 1, Jan 1996, p 25 [10 p, 10 ref, 6 tab, 17 fig]
• Authors:
  • Hua, J
• Publication Date: 1996

Language

• English

Subject/Index Terms

• TRT Terms: Probability; Rolling; Ship motion; Time; Time domain analysis
• Old TRIS Terms: Cargo shifting
• Subject Areas: Data and Information Technology; Marine Transportation;

Filing Info

• Accession Number: 00727520
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Nov 1 1996 12:00AM