7 
A Numerical Analysis——In a paper by D. W. Taylort 
a residuary resistance curve is given for 2 certain model 
(No. 892) from the result of tank experiments up to a value 
of c of 18. This is given almost exactly by (4) with a=2 
and B=82°5. All the results are now calculated in terms 
of effective horsepower for a ship on the same lines as the 
model. In the following table the column headed Ex- 
perimental E.H.P. was obtained in this way from the 
residuary resistance curve, while the calculated E.H.P. 
was found from (4) with the above values of a and B ; In 
both cases the total H.H.P. was obtained by adding a suit- 
able frictional part 0:00307f/SV2°83. 
The data for the ship on the lines of the model are: 
Displacement=400 tons; length=250 feet; wetted surface 
=5,000 square feet; longitudinal coefficient = 0°68 ; midship 
section coefficient —0°70; frictional coefficient—‘00897. 
Taste I.—EFrectivE Horse Power. 
| caer aaa 
Cc. Wa Experimental. Calculated. */, Wave. E.H.P./V*. 
0°5 79 53 54 11 109 
0:8 12°6 227 228 20 “112 
1:0 158 514 510 33 “129 
1:2 18-9 888 898 37 132 
1-4 22°1 1,495 1,495 42 | “144 
16 25°3 2,370 2,370 46 | “147 
1:8 28°4 3,360 3,360 47 147 
2:2 34°8 — 6,400 36 *152 
2°6 41:1 = 8,010 36 116 
3:0 47-4 — 11,160 31 “105 
4:0 63-2 — 22,250 23 088 
The agreement between columns 3} and 4 shows that the 
formula (4) is capable of representing the experimental 
results for this model. In regard to the calculated values 
at high values of ¢, it is of interest to compare these with other 
calculations. Cotterill* states that for certain types of torpedo 
boats the total resistance is approximately 30 c? for values 
of ¢ between 1°5 and 2°5; for the ship under discussion this 
would give the total E.H.P. as 582¢3. 'Uhis formnla gives 
D. W. Taylor, Trans. S.N.A.M.E. (New York, Vol. 16, p. 17 (1908). 
Cotterill, Applied Mathematics, p. 621. 
65 
