596 
W. J. Marwood and A. Silverleaf 
4/1 1417/777/7 SAXDED PORTION REPRESENTS GAIN 
IMMERSEO HULL 
W - WEIGHT 
4 - DISPLACEMENT 
T - RESISTANCE 
FOIL SYSTEM 
$ - WEIGHT 
L - WET 
o- enue 
Es 
he NW 
COMBINED SYSTEM 
W+s 2 AtL 
R = RESISTANCE 
=T+D 
TONS A FOR W 80 TONS 
Fig. 29. Possible performance of a partially immersed 100-foot boat and fully 
immersed hydrofoils 
Preliminary calculations suggest that hydrofoil support systems to carry half the weight 
of a conventional displacement type vessel should present no serious hydrodynamic or 
structural design problems, even if the foils are restricted to noncavitating types. 
ACKNOWLEDGMENTS 
The work described in this paper forms part of the research programme of the National 
Physical Laboratory, and the paper is published by permission of the Director, NPL. The 
assistance of Messrs. James and Stone, Ltd., Brightlingsea, Essex, in providing facilities 
for trial measurements on two launches, is gratefully acknowledged. 
NOMENCLATURE 
General 
A = Displacement 
L = Length (waterline), feet 
SS 
Il 
Speed, knots 
Speed, ft/sec 
= Draft, feet 
