Semisubmerged Ships 527 
meee = 
CO AN 8 gece Fo 
DESTROYER LENGTHENED DESTROYER 
SEMI-SUBMERGED SHIP 
SEMI-SUBMERGED HULL WITH LARGE STRUT 
SEMI- SUBMARINE 
SHALLOW - RUNNING SUBMARINE ©) 
DEEP-RUNNING SUBMARINE 
Fig. 1. Possible directions for seeking higher speeds at sea 
wavemaking resistance in the usual sense (because the speed is very high for the length of 
the strut), but there is separation of flow, ventilation, and even cavitation that cause a very 
large increase in resistance, usually designated spray drag, which shows very emphatically 
the reason for trying to make the strut as small as possible. 
For a typical destroyer (C), the EHP is considerably higher than for a submarine with 
a small strut, especially as speed goes up. In addition, this ship is slowed more than a 
submarine in rough water. 
Figure 2 also shows that a surface ship could achieve very high speeds if it were de- 
signed to be much more slender than a destroyer (K). This would reduce the surface 
