THE PROBLEM OF THE HULL AND ITS SCREW PROPELLER. 183 
Problem 2: Vessel of Type 3. 
Jey Ihe Wie Wises Blades = 3 
pa Form = Standard 
H=* AS = 
NY PXR=5772 
Bao I—S=.9225 
B al 52.55 
OO NO iy I. T.p=* 
alls VAM 13}. I. H. P.=225740 
EA Rota 1, CoS 5a 
Nome Bal e577, E. H. P.=118510 
B. C. on A—B=.418 S. H. P.=207680 
B. C. on A—B cor. for a HAUaR 
8 © =.60 
Slip B. C. on X=.45; S=.0775 Vin 
VE IBS (Cy a5 e. h. p.=*(bare hull) =*(est. all append.) 
K=I1 ena aes 
Number of propellers =4 ieley 
D=* Lime 
Ta [si 
Bis Jah Si Jal, Thai ayo) 
ID) aN Act. power=Between 150,000and 155,000 
Having illustrated the method followed in estimating the power required to 
drive a vessel at any given speed against the resistance existing at that speed, it 
remains to explain the method of estimating the revolutions at which the propeller 
will turn under these same conditions of estimated power and speed, and this will 
be taken care of now under the subhead— 
Estimate of Revolutions under Other than Basic Conditions of Operation. 
Commander S. M. Robinson, whom the author had the pleasure of calling his 
assistant during the period of the Great War, by laying down curves of revolutions 
of propellers of standard form with actual speeds through the water as abscissas, 
derived a curve of exponents, y, for which the equation is as follows:— 
5861.3 ) 
28045 + (v—25)* 
A curve of Log y was also erected on v as abscissas and the values of the logs of 
basic V” and v’ were denominated Log Ay and Log 4A,. 
The equation for apparent slip at any speed was found to be 
Uv 
MOS eae (2.626 + 
HSI Va et RV 
SME PASC Ow Tezaro 
*The data omitted are confidential and therefore cannot be made public. 
