Page 160 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 135
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Eds)
0 2001 Elsevier Science Ltd. All rights reserved

CALM WATER EXPERIMENTAL RESEARCH ON GEOSIMS OF
HIGH SPEED TRIMARAN: HYDRODYNAMIC
CHARACTERISTICS AND MODEL-SHIP CORRELATION

Ermina Begovic, Carlo Bertorello and Pasquale Cassella
Department of Naval Architecture and Marine Engineering University of Naples Federico I1
via Claudio, 21-80125 Napoli, Italy

ABSTRACT
In this paper a trimaran ship equivalent to a typical high speed craft in service in the bay of Naples has
been considered. Two vessels having different only outrigger hull forms have been designed on the
basis of required lay-out, of the limits in the main dimensions and of the available data from existing
design.
Calm water resistance model tests have been carried out for two main purposes:
Firstly, the investigation has been carried out on a large model in order to verify the influence of the
main hull trim and of the outrigger hull form and position on the trimaran hydrodynamic resistance.
Secondly, the investigation has been carried out on two geosim models of a trimaran hull configuration
with the goal to compare the ITTC’57 with the ITTC’78 model-ship correlations.
For this last purpose a form factor of the trimaran has been determined by different methods. The
results show that the ITTC’57 could be preferable to ITTC’78 model-ship correlation, in the higher
Froude number range.

KEYWORDS

Trimaran. Passenger ferry. HSC, Resistance test, Model-ship correlation

1 INTRODUCTION
The last years have seen a remarkable increase in the number of high speed craft operating all over the
world. The current trend in high speed vessels, especially for coastal car-passenger ferries has led to
the search for-hull forms with superior characteristics.
Several comparisons among multihull and the monohull ships, on the basis of equivalent service
capabilities, have highlighted the advantages of each hullform; the catamaran is known to be very well
adequate to the above mentioned service.
Furthermore, in recent years, interest about the trimaran ships has been growing because of the
advantages due to their large deck area and to the increased stability under damaged conditions. In
addition, by making the main hull very slender and optimising the wave drag by means of side-hull