Page 151 - Practical Ship Design

118 Chapter 4

Some comments first of all on Fig. 4.18. The powering on this sheet uses 0 either
to Froude or to ITTC with a corresponding need to invoke an appropriate (1 + x)
value. If the three trial ships method mentioned in $3.1.1 is used, each trial ship can
be designed on a page of this type, or alternatively a revised version of the sheet
can be drawn up with three or four columns. Whilst the sheet was originally
designed for use in preliminary design, it can be used to record the main particulars
of a design as these change throughout the design process and can also be used to
store “as fitted” data on completed ships in a form particularly useful for design
work.
The updated version presented as Fig. 4.19a-d is a computer spreadsheet which
greatly increases the speed and improves the accuracy with which all the calcu-
lations can be made. There is, of course, automatic addition of each of the columns
of weights together with transfer of totals to the lightship summation giving a
progressive updating as the design proceeds. All the formulae used are built in to
the program - some of these formulae appear on the spreadsheet, but others which
would have taken up too much space are summarised below.
Address Formula
c23 eq. (3.5)
c24 eq. (3.9)
c26 eq. (3.14)
m28 eq. (4.2)
x30 eq. (6.38)
Much of the data required when using the spreadsheet are given in tables or graphs
in the book generally under the following references.
Address Data
c12 Fig. 3.3
c16 Fig. 3.5
c 18,19,20 Figs. 3.7, 3.8, 3.9, 3.10
c22 $3.5
f34 $3.5.2
j20 $4.3.2
j25 54.6
m7 $4.2
m23 Fig. 4.1 and Table 4.1
m37 Figs. 4.12 and 4.13 and $4.4
m40 Figs. 4.15 and 4.16 and $4.5
m4 1 Fig. 4.17
q4 $4.3
q8 Fig. 4.8
q26 Fig. 4.2
q29 $4.5
t4 $4.4