Page 217 - Practical Ship Design

182 Chapter 6

C(stern) = +8 C(stern) = -8

C(stern) = -18 C(stern) = -22

Fig. 6.3. Different stem types and C,,,, values.

The need for Cp values corresponding to the C,, values chosen was met by
plotting Fig. 8.9. This shows values of C, for ships with no rise of floor, with a low
rise of floor and a high rise of floor. The first two representing merchant practice,
the latter that of frigates and corvettes.
Cb 0.55 0.70 0.85
cm 0.97 0.975 0.98
CP 0.567 0.7 18 0.867
V 8232 10477 12722
LCB -2.5% (aft) amidships +2.5% (ford)
Sections normal normal normal

All three ships LIB = 7.28 TIL = 0.06
For these three ships with identical main dimensions the factors affecting (1 + K) can
be seen to be factors 4,5 and 6 - the position of the LCB, the volume of displace-
ment and the prismatic coefficient. The fact that the effect of fullness reduces 5 but
increases 6 suggests that it might be possible for these two factors to be combined.