Page 152 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 127
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Eds)
0 2001 Elsevier Science Ltd. All rights reserved

THE DESIGN OF TRIMARAN SHIPS: GENERAL REVIEW AND
PRACTICAL STRUCTURAL ANALYSIS

T. Coppola, M. Mandarin0
Dipartimento di Ingegneria Navale, University of Naples “FEDERICO 11”
Via Claudio 21 80125 Naples Italy

ABSTRACT
In the last years, the applications of fast commercial transport at sea have aroused an increase of high-
speed ships demand. More in particular mono-hull and catamaran passenger ships, in service on brief
routs, are able to halve, respect to the conventional ships, the voyage times.
More of recent, the attention has been moved on multi-hull vehicles with function also of container
ship in service on transoceanic routs.
In this respect, the trimaran configuration seems to be more encouraging to combine greater demands
of space and high speeds.
The main characteristics of a trimaran can be so synthesized:
The main-hull is more slender than the actual mono-hull (LA3 would change among 12 and 18),
with a consequent wave resistance reduction.
Two lateral hulls with very small displacement than that one of the main hull; their fimdamental
function is that one of maintaining a suficient stability of the ship and furnishing a bigger decks
area.
The main objective of the paper is to validate the greater advantages offered from the trimaran ships,
for commercial, tourist and naval fields: better available surface for decks; reduced interference of
weapon systems; large flight deck area; possibility of realizing multifunctional naval ship (Le. frigates
with particular characteristics of air, surface and A.S. zone defense).
In this respect firstly, an investigation has been carried out, on the possible fields of applicability of the
trimaran ships; then models of global maximum loads have been proposed.
A discussion has been carried out about the preliminary design of trimaran. Particularly the autonomy
problem and the hull forms optimization problem have been treated. In addition, a method has been
developed for the global load evaluation.
The numerical example show that the torsion stresses are negligible for trimaran; the shear and
bending stresses are instead very relevant and decide for the transverse strength of trimaran.

KEYWORDS

Trimaran. Global Loads, Design, Structures, Main-Hull, Multi-hulls, Outriggers, Naval.