Page 196 - Introduction to Naval Architecture

182 RESISTANCE

Figure 8.5 Resistance curves

Scaling wave-making resistance
It has been shown that for geometrically similar bodies moving at
corresponding speeds, the wave pattern generated is similar and the
wave-making resistance can be taken as proportional to the displace-
ments of the bodies concerned. This assumes that wave-making was
unaffected by the viscosity and this is the usual assumption made in
studies of this sort. In fact there will be some viscosity but its major
effects will be confined to the boundary layer. To a first order then, the
effect of viscosity on wave-making resistance can be regarded as that of
modifying the hull shape in conformity with the boundary layer
addition. These effects are relatively more pronounced at model scale
than the full scale which means there is some scale effect on wave-
making resistance. For the purposes of this book this is ignored.