Fig.15 |
Time histories of ship's speed u,yaw rate r and drift angle β in turning motion under wind force (type-C, rudder angles of 35 degrees). |
Fig.16 |
Simulation results of 10-10 zig-zag maneuver under wind force(type-C). |
5. CONCLUSIONS
On the basis of this simulation studies, the effects of wind force in maneuvering motion are discussed quantitatively for Philippine outrigger craft. Meanwhile, free running model tests were conducted to check the accuracy of the prediction method. The following conclusions are drawn:
1) The prediction method of maneuverability for Philippine outrigger craft is proposed, and the accuracy of the prediction method is adequate to consider safety of navigation.
2) The outriggers have influence on increasing resistance as much as resistance of a hull, but the influence of the distance between outriggers is rather slight.
3) The maximum deviations in the turning motions are quantitatively obtained from the simulation studies for the craft with wind conditions.
4) As the draft of outrigger craft is shallow, yaw rate and drift angle are strongly influenced of wind force in turning motion.
5) The hull of Philippine outrigger craft is so slender and outriggers are large damping of yaw moment. Accordingly the craft has an excellent course keeping ability.
ACKNOWLEGEMENTS
The authors wish to express their gratitude to Mr. Y. Yamakoshi, Dr. N. Ma, Mr. A. Matsuda and Mr. S. Suzuki for their supports through out model experiments in the National Research Institute of Fisheries Engineering (NRIFE).
We also wish to thank students of University of the Philippines in the Visayas and Faculty of Fisheries, Kagoshima University for their supports.
REFERENCES
[1] Aguilar, G "Comparative analysis of hull forms of selected Philippines indigenous fishing craft", University of the Philippines in the Visayas Journal of Nature Science, Philippines, Vol. 2, pp. 17-43, 1997
[2] Aguilar, G "Computer modeling of indigenous fishing craft", University of the Philippines in the Visayas Journal of Nature Science, Philippines, Vol. 2, pp. 44-59, 1997
[3] Shigehiro, R., Aguilar, G, and Kuroda, T "Turning Performance of Outrigger Craft in the Philippines", UPV Journal of Nature Science, Philippines, Vol. 2, pp. 25-35, 2002
[4] Aguilar, G., Shigehiro, R. and Kuroda, T. "Resistance of Philippine outrigger craft", UPV Journal of Nature Science, Philippines, Vol. 2, pp. 36-46, 2002
[5] The Society of Naval Architects of Japan: Proceedings of the 3rd Symposium on Ship Maneuverability, pp. 27-80, 1981
[6] The Society of Naval Architects of Japan: Proceedings of the 4th Symposium on Ship Maneuverability and its Application, pp. 191-223
[7] Isherwood, R. M. "Wind resistance of merchant ships", Trans. RlNA, Vol. 115, pp. 327-338, 1970
[8] Tsuji, T., Takaishi, T., Kan, M. and Sato, T. " Model test about wind forces acting on the ships", Report of Ship Research Institute of Japan. Vol. 7, No.5,pp. 13-37, 1971
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