Report on the USS ORTOLAN (ASR-22) Forward Foil Seakeeping Trials.
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD SHIP PERFORMANCE DEPT
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This report presents and discusses the results of seaworthiness trials conducted aboard the USS ORTOLAN ASR-22 subsequent to the installation of a between-hull forward foil and modifications to the forward bridging structure. Ship motion, hull strains, and bridging structure impacts are presented with comparisons made between the as built and the modified conditions. Results indicate that the addition of the foil, along with the bridging structure modifications, significantly improved the seaworthiness characteristics and operational limits of ORTOLAN, yielding a capable, seaworthy craft. Bridging structure impacts did not limit ORTOLANs ability to transit at any heading or speed in seas up to and including a state 6 sea. Ship motions, while large, are not abnormal and strain measurements indicate that the main structural integrity of the ship at the locations investigated was not endangered at any time during the trials. However, local structural modifications are required on the second deck between Frames 12 through 21 along the port and starboard inboard hull plating. The foil did not break the water surface in seas having a maximum wave height over 30 feet.
- Marine Engineering