April 15

April 15

“Some Hydro-Structural Aspects of Large Container Ships”

by John Kokarakis


The 8th technical meeting of the Greek Section for the 2009-10 season was held on Thursday April 15th at the Maran Auditorium in Athens.

The technical topic of the evening was related to the hydro-structural aspects of large container ships and the impact of related phenomena on the design. The topic was presented by Gijsbert De Jong, in charge of technical developments for this type of ships at Bureau Veritas. Although, these vessels have suffered a setback recently, it became clear that research and technical analysis towards better designs continues. Main hydro-structural phenomena presented were the whipping and springing. The former is related to the effect of high pressure loads at the ship ends on the stresses amidships. The later is an offshoot of the trend for longer and more flexible ships resulting in lowering of the natural frequencies of bending vibrations. This fact coupled by the increase on wave encounter speed due to the high speeds of containerships might lead to resonance effects and induce significant stresses. On the basis of both full scale measurements and hydro-elastic analysis the effect of stress increases on fatigue damage were studied. It was concluded by the presenter that for the cases studied the effect on fatigue damage was up to a 10% increase. Finally, container lashing analysis was presented as a “base excitation” problem and there was an interesting discussion on why containers are lost at sea. Coupled to this effect was the phenomenon of parametric roll which was also analyzed. The presentation was concluded with a lively and interesting question and answer session. As always the evening closed with the traditional get together reception at the hospitable rooms of the Angelikoussis  Group of  Companies.  

 from left to right:

V. Dimoulas, G. Andreadis, P. Palaiologou, all three from Bureau Veritas, Piraeus;  N. Dionysopoulos, current Membership Chair;
G. De Jong, Author;  P. Lalangas, Chair; L. Chahalis, new membership chair ( 2010-12 );  J. Kokarakis, Vice Chair; K. Maounis. Secretary / Treasurer