Describes a theoretical method for predicting the forces induced by irregular waves on very large crude carriers, in which the hull section is modeled as a prismatic elliptic cylinder. Diffraction of the wave around the elliptic cylinder is taken into account and results are presented for surge and sway force and yaw moment for incident wave angles from 0 degree (head-on) to 90 degrees (broadside-on) at several increments and water depth to draft ratios. Thus, the effect of underkeel clearance is taken into account. In order to verify the method, an experimental study utilizing the captive model technique was carried out at the Netherlands Ship Model Test Basin (NSMB). In this study, forces (and moments) in the surge, sway and yaw directions were measured as the real tanker shape models were subjected to irregular waves incident from 0 degree to 90 degrees at several values. The comparisons, which are presented in terms of the non-dimensional force (or moment) ratios, are considered to be excellent. The procedure described herein can be employed to synthesize external loading histories due to irregular waves acting on very large crude carriers of specified dimensions for a variety of incident wave angles and water depth/draft ratios. The technique can also be employed to derive added mass and damping coefficient functions for the specified tanker. The procedure is an intermediate step in the process of determining the behaviorial response of the moored vessel. The vessel can be considered as moored to conventional piers in relatively protected areas or to sea islands or sea berths in exposed locations. The combination of low computational cost and reasonable accuracy makes it an ideal procedure to employ for a number of engineering applications.

Media Info

  • Features: References;
  • Pagination: p. 125-142

Subject/Index Terms

Filing Info

  • Accession Number: 00138205
  • Record Type: Publication
  • Source Agency: Offshore Technology Conference
  • Report/Paper Numbers: V2, OTC 2535 Proceeding
  • Files: TRIS
  • Created Date: Aug 23 1976 12:00AM