Page 117 - Practical Ship Design
P. 117
84 Chapter 4
4.2.4 Plotting the steel-weight against E
Because of the wide range of ship sizes that this book tries to cover, the only
satisfactory plot of steel-weight that can be achieved without resort to an outsize
piece of paper requires the use of a log-log scale, as shown in Fig. 4.1. It will be
seen that this achieves reasonable accuracy for small ships whilst allowing the
steel weights of the largest vessels to be included in the plot. The accuracy with
which steel-weights can be read off from this small graph is however limited by the
scale and the difficulty in showing the large number of closely spaced lines needed
to differentiate between different types of ship. As today's computer users prefer
100 000
NET
STEEL
(TONNES)
100 1000 no00
E - WLL NUMERAL M2
Fig. 4.1. Net steel weight vs Lloyds equipment number E. The line shown is a mean through most
of the spots irrespective of ship type and has the formula W = 0.33 E'.36.
