(Excerpt from the Proceedings of the 
University of Durham Philosophical Society, 
Vol. Ifl., Part 4.) 
Surp-Resistance: A NUMERICAL ANALYSIS OF THE 
DistripuTion oF ErrectivE Horse Power. 
By T. H. Havetocg, M.A., D.Sc. 
[Read January 24th, 1910.] 
Introduction.—The following paper contains, in its second 
part, a numerical study of the distribution of effective horse- 
power at different speeds. The data are taken from some 
recent experiments on models by D. W. Taylor, and are 
expressed for a ship of 400 tons displacement and 250 feet 
length. A theoretical formula is found to fit the experimental 
results, and from it the different terms in the E.H.P. are 
calculated for much higher speeds. In addition to the 
general analysis, attention is directed to the changes in the 
proportion of power which goes in wave-making, and also to 
the variation of the ratio E.H.P./(speed)* with the speed; in 
the latter case a curve is drawn and may be compared with 
the type of curve obtained from high-speed motor boats. 
In the first part, an outline is given of the general theory 
of ship resistance; it is developed so as to lead to the introduc- 
tion of a type of expression which exhibits the variation of the 
wave-making resistance with the speed, but for details of the 
mathematical analysis reference is made to previous papers.* 
One obtains a general formula which is based on theory in so 
far as it depends upon the speed, and with co-efficients which 
should depend upon the form of the ship but whose values 
are at present empirical. No attempt has been made to 
tabulate values suitable for different types of vessels, for 
without further information, it is uncertain whether the 
results would repay the labour; meantime, as already 
indicated, the formula has been used to analyse experimental 
* Proceedings of the Royal Society, A, vol. 81, p. 398 (1908); A, vol. 82, 
p. 276 (1909). 
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