Page 173 - Practical Design Ships and Floating Structures

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5 CONCLUSIONS
Systematic model tests have been carried out on a trimaran hull equivalent to operating high speed
catamaran and monohull ships. Resistance and wave pattern tests have been carried out separately on
the main hull, on the outrigger and on the trimaran. Seakeeping tests have been also carried out on the
main hull and on the trimaran for AIL 0.5-1.5. The resistance results have been analysed by ITTC 57
model ship correlation.
From the results of this experimental research program the following consideration can be derived:
- due to very slender hulls the wave resistance of the considered trimaran is a low percentage of the
total resistance;
- the wave interference phenomenon is generally beneficia!:
from the comparison with monohull and catamaran, the trimaran seems preferable in the Fnv range -
1.8-3.O.Then for Fnv>3 the monohull ship seems to become the best hullform.
Preliminary seakeeping tests in regular waves show very significant differences of heave and pitch
motions of the trimaran with respect to those of its main hull. The reported data seem to indicate a
significant beneficial effect of the outriggers on the seakeeping performances. Further study is
however necessary to confirm these results and to evaluate other configurations with different
outrigger position so to have indications also for what seakeeping optmisation is concerned.
Acknowledgments

This work was supported by the Italian Ministry of University and Scientific Research in the frame of
the 1999-2001 research plan.
References

Ackers B.B.; Micheal T.J, Tredennick O.W., Landen H.C., Miller E.R., Sodowsky J.P., Hadler J.B.
(1997). An investigation of the Resistance Characteristics. of Powered Trimaran Side-Hull, SNAME
Trans., 105,349-380
Battistin D., Danielli A., Zotti I. (2000). Numerical and Experimental Investigations on Wave
Resistance of Trimaran Configuration. Proc. of ZUAM 1,56-63, Ischia, Italy
Begovic E., Migali A., Pensa C. (2000). Experimental Study on the Resistance of a Trimaran Hull
Configuration, Proc. of NAV2000,2.6.1-2.6-10, Venice, Italy
Bertorello C. (2000). Trimaran Hull Performances for Fast Passenger Femes Proc. of NAV 2000.
2.4.1 -2.4. IO. Venice, Italy
Bertorello C., Bruzzone D., Cassella P., Zotti I. (2001). Experimental Performance Investigation on
Different High Speed Crafts: Monohull Catamaran and Trimaran Hiper 2001 May 2001 Hamburg, Germany
Brizzolara. S.. Bruzzone, D., Cassella, P., Scamardella. A., Zotti, I. (1998). Wave Resistance and
Wave Patterns for High Speed Crafts; Validation of Numerical results by Model-Test, Proc. xyll
Symposium on Nuvul Hydrodynamics, 55-69, Washington, USA
Cassella, P., Coppola, C., Lalli, F., Pensa, C., Scamardella. A., Zotti, 1. (1998). Geosim Experimental
Results of High Speed Catamaran: Cooperative Investigation on Resistance Model Tests Methodology
and on Model-Ship Correlation, Proc. PRADS 1998,447-452, The Hague, Holland
Eggers K.W.H., Sharma, S. D., Ward, L.W. (1967). An Assessment of Some Experimental Methods
for Determining the Wave making Characteristics of a Ship Form Trans. SNAME, 74.
Larsson L., Janson C.E., Brun P. (1997). A Numerical Investigation of Trimaran Configuration, FAST
97,537-544, Sydney, Australia
Suzuki K., Nakata Y., Ikehata M., Kai H. (1997). Numerical Prediction on Wave Making Resistance
of High Speed Trimaran, FAST 97,611-620, Sydney, Australia
Suzuki K.. Ikehata M. (1993). Fundamental Study on Optimum Position of Outrigger of Trimaran
from view Point of Wave Making Resistance, Proc. ofFAST 93, 1219-1230, Yokohama