High Performance Ships—Promises and Problems 7 
Within the past 10 years technological advances have been exploited to make the sub- 
marine the most fantastically mobile and powerful warship yet devised. 
The foregoing are all promises realized, but progress in improving the performance of 
submarines still encounters problems. The problems essentially consist of a search for 
methods ofimproving this already powerful vehicle. The most significant improvement would 
be to increase speed. The most direct way, of course, is simply to increase the power. 
This would require a larger hull, so that some of the gain would be eaten up in added fric- 
tional resistance. A simplified parametric study holding payload constant and using present 
- specific weights and volumes for machinery, indicates that a submarine would require well 
over 100,000 shaft horsepower to attain 50 knots. This is right at the upper bound of pres- 
ent technology as regards the power that can be absorbed by a single propeller. Improve- 
ments in specific weights and volumes of submarine power plants will naturally improve this 
situation, but it is apparent that dramatic increases in speed will be hard earned. Other 
methods of improvement, such as reduction of resistance by boundary layer control will be 
discussed in a later portion of this paper. 
Near Surface Craft 
The near surface craft is intended to combine the stealthiness, speed, and motion char- 
acteristics of a submarine with the air-breathing, air-communication aspects of the surface 
ship. 
At present, nuclear power plant weights are extremely high compared with the more 
advanced air-breathing plant. If the submarine could be run sufficiently close to the surface 
to breathe air through a slender strut, and still stay far enough down to avoid excessive 
wave drag, a lightweight air-breathing plant could be used. 
The near surface craft is intended to do this. Work on this type is currently being per- 
formed by the Davidson Laboratory. Fig. 6 shows a series of speed-power curves, as a 
function of depth of submergence, for an arbitrary submarine type hull form. In order to 
4 
‘ Aa 
/ 
DESTROYER ie ee 
/ 
ve 
1.25 DIAS_/ 
1.58 eee 
SUBMARINE SUBMERGED + 366 
HORSEPOWER 
SPEED 
Fig. 6. Effect of the depth of submergence on the speed-power 
curves for a submarine 
