Stealth is the raison d ‘etre for submarines. Any other performance characteristic which might jeopardize stealth may rightfully be challenged. For this reason, submarine speed is not always considered to be a critical requirement. Indeed, the percentage of volume and weight allotted to sound quieting is likely to increase for future classes of Western submarines, while that dedicated to propulsive power is likely to decrease. Hence, advances in power density technology may be effectively cancelled by the ever increasing demand for sound quieting.
The advantages of speed, considered independently from stealth, are obvious and include rapid deployment, increased rate of area coverage, and tactical advantage in a melee. However, those advantages can be negated if stealth is sacrificed. It is apparent that there are trade-offs between speed and stealth. The question which must then be considered is whether or not the relationship between speed and stealth is mutually exclusive.
It is possible that the conflicting goals of stealth and speed may be simultaneously achieved in some different technology regime.
U.S. submarines which emphasize stealth have a technology regime defined by steam generators, SSTGs, MPGs, reduction gears, and traditional screw propellers. In this regime, increases in propulsive power tend to generate higher noise levels. To suppress these noise levels, higher quality equipment mus’t be developed or greater volumes be allocated to facilitate quieting. Thus, a significant increase in power may result in little increase in speed. However, other power technologies may exist outside this regime in which increases in power are not necessarily accompanied by increases in cost or in acoustic detectability.
Are there technologies where the functions of heavy reduction gears, large rotating electrical machines; and steam generators are eliminated or can be replaced by some low-noise or less costly system?
Fuel cells readily come to mind, particularly if they can be recharged with radiation or heat from a nuclear reactor. Another option is magnetohydrodynamic (MHD) technology which can provide silent thrust as well as power generation. If U.S. submarines are to move into the speed range of Soviet submarines without sacrificing stealth, alternative cost effective regimes of technologies–regimes in which improvements in speed and stealth could be achieved simultaneously may hold the answer.