Huang and von Kerezek 
(3) Total and residual resistance. The measured total resis- 
tance and the residual resistance, Cp = Cr - Cr , are shown in Fi- 
gure 8, where the 1957 ITTC friction line was used to detente 
Cy for all of the data. The other data of the geosims by Todd ?®, and 
by Tsai and Landweber ”” (parent hull without stern modification are 
also shown. The 6-, 10-, and 14- foot models were tested in the 
Iowa Tank. The Cp ofthe 10- and 14- foot models is higher than 
that of 6- and 20- foot models. The 20 model was tested in NSRDC 
basin I and II. However, reasonable agreement for the 6- and 20- 
foot models is noted. The Cy of the present 20- foot model was 
measured in NSRDC basin I and II by a floating girder and a block 
gage. Turbulence stimulation, a row of studs, 1/8 -inch in diameter, 
0. l-inches in height, and 1-inch in spacing was used in one of the 
tests. No significant difference in C. with the turbulence stimulator 
was found. The discrepancy in Crp's among the four present tests is 
less than 2%. 
(4) Pressure distribution. If the flow is assumed irrota- 
tional, then the Bernoulli equation in the o'x'y'z' coordinate system 
is 
P2 
p 
Pp : 1 2 a 2 
oe = NM Peer = 18872 are Px + ey + e2'| = 
where V is ship speed, Pg is the atmospheric pressure and ¢ the 
perturbation potential. We define the pressure coefficient by 
Hed ALLO AK AORN AA 
G0 th —— : y 
: p v’/2 xia (6) 
which yields Cp =1 at the stagnation point where %, = V and 
Yy = ¥z = 0. If the linearized free-surface boundary condition is 
used, at any waterline below the undisturbed water surface ¥ reduces 
CO Pie Phy 92) exp (gz'/v*)¢ (x', y', z' = 0), From Equation (6) we 
have 
gud tuileli aah: cxp| ete (7) 
1942 
