Running parallel to increase current - gives more torquing power, more turns, if you do this you will decrease the ampere-hour rating of the battery, meaning it aint going to last too long.
from the manual:
Various combinations of armatures in series or in parallel, including the coupling of all four motors in series for dead slow operation, may be obtained, for either surface or submerged operation, through the main control cubicle.
For surface operation, motor speed control is accomplished by controlling the generator speed and shunt field, thus varying the voltage supplied. When submerged, speed is controlled by varying the motor shunt field or by connecting the motors in different combinations of series and parallel. Reverse operation is accomplished by reversing the direction of the flow of current in the motor armature circuit.
For surface operation, using the various combinations of armatures and taking power from the main generators, the motors develop from 20 hp to 2700 hp per propeller shaft at speeds ranging from approximately 67 rpm to 282 rpm.
For submerged operation, using various combinations of armatures and taking power from the batteries, the motors develop power ranging from 30 hp to 1719 hp per propeller shaft and give a speed range from 38 rpm to 219 rpm.
