12 THEORY OF SHIP WAVES AND WAVE RESISTANCE. 
calculations corresponds to a simplified form of certain well-known 
sets of experiments with ship models, into the details of which we 
need not enter. It may be sufficient to quote one example, which is 
typical of the results. D. W. Taylor, referring to a series of experi- 
ments with models of the same displacement and of varying midship- 
section coefficients, states that the models with full midship-section 
coefficients drive a little easier up to V/,/L equal to 11 to 1:2, and 
Fie. 6 
the models with fine coefficients have a shade the best of it at higher 
speeds. The agreement with the intersections of the curves in Fig. 5 
is rather striking. 
Parallel Middle Body.—Take now the simple form of model A and 
insert varying lengths of parallel middle body between bow and stern, 
so that the water-plane section is like Fig. 6. 
Ton T T 7 T T T T v Toa a 
4 
A 
L 410 
L sb 
A, dh 
\\ IL 
A 
p 6 
A rai 
L - 5 
C) Ale 
Ir A J 
vy 
ae. NV 
1 1 J 1 1 1 = 
180 2k 140 100 60 20 (0) 
Fie. 7. 
The calculations lead to curves showing how the wave resistance 
at a given speed varies with the length of parallel middle body (Note 6). 
Some curves are shown in Fig. 7. The base is the length (2k) of 
parallel middle body, and the entrance and run were each taken to 
258 
