THE EFFECT OF ENTRAPPED AIR UPON THE SLAMMING OF SHIPS' BOTTOMS

The effect of entrapped air on the slamming of ships' bottoms is examined with regard to dry cargo merchant ships. Experimental results, contrasted with the predictions of Ogilvie's theory, are presented along with outlines of new theoretical work based on them. Both one-dimensional and two-dimensional theories are advanced. The two-dimensional theory provides reasonable estimates for the duration and magnitude of peak centerline pressure during water impact. Further experimental work is desirable, especially to check some of the theoretical predictions of water and air movement. A more detailed analysis of the initial conditions is also required. A significant feature of the new theory is that, whereas both compressible and incompressible movement of the water is assumed to take place, the time scale of events is so long that the compressibility of the water is of less importance. Therefore flat impact is largely a hydrodynamic phenomenon. The magnitude of the peak pressure is dependent primarily upon the hydrodynamic added mass and the velocity of the water surface at coalescence.

  • Supplemental Notes:
    • This document is available for review at the Department of Commerce Library, Main Commerce Building, Washington, D.C., under reference number UCB-NA-66-5.
  • Corporate Authors:

    University of California, Berkeley

    College of Engineering
    Berkeley, CA  USA  94720
  • Authors:
    • Lewison, G
    • Maclean, W M
  • Publication Date: 1966-3

Media Info

  • Features: Appendices; Figures; Photos; References;
  • Pagination: 62 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00026991
  • Record Type: Publication
  • Source Agency: Maritime Administration
  • Report/Paper Numbers: NA-66-5
  • Contract Numbers: MA-2620
  • Files: TRIS, USDOT
  • Created Date: Jun 15 1973 12:00AM