Aspects of SWATH Design and Evaluation

Miller, Alexander Ferguson (1991) Aspects of SWATH Design and Evaluation. MSc(R) thesis, University of Glasgow.

Abstract

This thesis describes research intended to extend and enhance the existing SWATH design capability developed at the University. The thesis commences (Chapter 2) with a brief general review of all design aspects relevant to the balanced evaluation and comparison of monohull and SWATH vessels. SWATH vessel performance in each of these areas is analysed individually, and where possible quantified in relation to that of corresponding monohull ships. This chapter is intended to highlight the range and extent of the variations existing in SWATH / monohull design and operability characteristics. Chapters 3, 4 and 5 of the thesis describe studies aimed at improving our understanding of the often neglected although fundamental aspects of damage stability, manoeuvring and wave induced global loading. These design topics were selected for investigation after the preliminary review highlighted shortfalls in the availability and reliability of relevant information. Chapter 3 addresses the question of damage stability. Results from an extensive parametric study undertaken to explore the damage stability characteristics of SWATH vessels are presented and discussed. Secondly the relationships thus established between design geometry and damage stability are utilized in the construction of 'FSEP1'; a design program which estimates damaged stability characteristics at the preliminary design stage. Chapter 4 investigates the manoeuvring performance of SWATH ships. Following a thorough literature survey, conventional (monohull) manoeuvring theory is applied and adapted to create a manoeuvring prediction tool for SWATH vessels; 'SWATHMAN'. This program will estimate required rudder areas in order to achieve a specified manoeuvring performance. Conversely the program will estimate the likely turning performance for a specified rudder area. The program incorporates propeller acceleration effects and caters for control fins mounted in and outwith the slipstream. Chapter 5 reviews aspects of wave loading in the structural design of SWATH ships. It is widely acknowledged that wave induced side force leading to a transverse bending moment is the dominant form of environmental loading for these vessels. All available methods for the calculation / estimation of this force were therefore identified and applied to the vessels T-AGOS 19 and the M. V. Patria. Short term extreme value prediction methods are applied in order to determine likely lifetime values of design extreme loading. Empirically derived estimates are compared with those produced by the application of rigorous three dimensional potential theory, and conclusions on the applicability of the methods are drawn. Finally chapter 6 outlines a method for the overall mission based evaluation of alternative monohull and SWATH designs. This comparison is based on all relevant features of the two concepts. Features and characteristics of both hullforms are identified and assigned a priority level. The priority level assigned includes consideration of the vessel's intended role and operating profile. Through application of this technique the chapter aims to provide guidance for the designer selecting hullforms for both general and specific roles.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Naval engineering
• Date of Award: 1991
• Depositing User: Enlighten Team
• Unique ID: glathesis:1991-78318
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:33
• Last Modified: 30 Jan 2020 15:33
• URI: https://theses.gla.ac.uk/id/eprint/78318