Page 35 - Practical Ship Design

6 Chapter 1

1.1.6 The general layout of the book

The next two sections of this chapter deal in a general way with design methods
and design data respectively. The section on design methods starts by discussing
the place of some of the “back of the envelope” type calculations outlined in later
chapters and then goes on to describe computer methods and how these can speed
up and increase the accuracy of design work.
The section on data outlines the importance of data to a naval architect and the
need to store this in an easily accessible format. The sources drawn on in the
writing of this book are given together with suggestions of other sources that
designers will find useful.
Chapter 2 starts by dealing with the very important subject of setting the design
requirements. For merchant ships this task will often be carried out by the
commercial side of a shipping company; for warships by naval staff; for specialist
ships by the scientists or others involved in the specialism. The naval architect has,
however, a great deal to contribute to this task and should be fully consulted. If he
is not so consulted he should have no inhibitions about questioning the design
requirements with which he is eventually faced. The chapter then introduces the
design spirals for merchant ships and warships, compares these and goes on to
suggest how to establish which criteria are most critical in seeking a solution which
meets the requirements.
Chapters 3,4 and 5 draw quite largely on the R.I.N.A. paper “Some ship design
methods” which the author wrote in 1976 in collaboration with A.W. Gilfillan, to
whom he is indebted for permission to draw on this joint work. Most of what was
written in 1976 seems to have stood the test of time very well, but some updating
has of course been necessary and there has been some expansion of a text which
was originally limited by R.I.N.A. publication guidelines.
Chapter 3 gives the fundamental design equations for both weight and volume-
based designs. This includes data on the dimensional relationships applicable to a
variety of ship types. Data on the deadweighddisplacement ratio and the cargo
capacityhull volume ratio are given, again for a variety of ship types.
Chapter 4 deals with weight-based designs describing both approximate and
detailed methods for calculating steel-weight, outfit weight and machinery weight.
Chapter 5 deals with volume-based designs describing how to calculate the
volume required to accommodate all the space requirements of a passenger ship
and how to translate a space requirement to appropriate ship dimensions.
Chapters 6 and 7 which deal with powering, Chapter 8 which follows on to the
closely related subject of the ship lines, and Chapter 9 which deals with machinery
selection all draw on the author’s Parsons Memorial paper “Designing ships for
fuel economy” published by R.I.N.A. in 1981.