Page 145 - Practical Ship Design
P. 145
112 Chapter 4
10000
Total
Machy
1000
Weight
Tonnes
100
Fig. 4.17. Total weight of diesel electric machinery.
If the there is to be more than one type of propulsion machinery --e.g., gas
turbines and diesels - then the weight of these components should be separately
assessed.
Catalogue data should be used if available, but if not the weight per kilowatt for
high speed diesels and gas turbines given in 94.5.4 can be used.
The weight of the remainder can be estimated using eq. (4.10) with the approp-
riate K value. It will be noted that the K value for warships is much smaller than
that for any merchant ship type, although a warship has many more machinery
items and more complicated systems. This indicates the great care that is taken to
minimise weight on these fast fine lined ships.
If the machinery is an “and’ configuration the power used for estimating the
weight of the remainder should be the total installed power machinery, but for an
“or” configuration the power used should be that for high speed operation.
4.5.8 Detailed machinery weight calculations - merchant ships
For detailed machinery weight calculations it is essential to have a standard list of
items so that calculations are always made in the same order and the danger is
reduced of something being omitted.
