Albacore was originally built with one motor, one propeller shaft and one propeller. As part of the Phase Four conversion package, this compartment was cut open and extended in length to accommodate a second main motor which was placed aft of the original motor. Each motor can produce 75 hundred horse power. The original propeller shaft connected to the forward motor was replaced by a smaller diameter shaft that fit inside the second, hollow shaft attached to the after motor. The motors were wired such that they always turned in opposite directions.