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Optimization of Bow-Bulb Forms for Resistance and Seakeeping Characteristics.

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Final rept. 1984-1985,

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This report presents the results of an investigation of bulbous bows for fine form ships conducted as a Trident Scholar research project. Nine different bulbs were designed for the OLIVER HAZARD PERRY FFG-7 Class of Ships. These bulbs varied primarily in length and breadth and were designed using a Naval Sea Systems Command application of the Kracht bulb design curves. Resistance predictions were obtained for the FFG-7 appended with eight of these bulb forms from the XYZ Free Surface Program. Seakeeping characteristics were predicted for the appended FFG-7 with the aid of the Navy Standard Ship Motions Program. Resistance and seakeeping predictions were also obtained for the unappended PERRY hullform and the FFG-7 appended with an existing bow bulb similar to that found on the Italian frigate, MAESTRALE. Finally, model tests were performed at the U.S. Naval Academy in calm water and irregular, head seas on six different configurations of the PERRY hullform unappended, appended with MAESTRALE-style bulb, and appended with four newly designed bow bulbs. The FFG-7 hull form was also appended with a fifteen degree stern wedge during all computer runs and model tests. A comparison of the computer predictions and model test results is presented, along with a determination of the applicability of the bulb design method utilized to develop the bulb form. The effects of changes in bulb length and breadth are also investigated. Author

Subject Categories:

  • Marine Engineering
  • Fluid Mechanics

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