Underwater Propeller Change,
USS Enterprise, CVN-65

Boss Nut Removal Attempts

Removing the boss nut was the next major step in the propeller change. Divers first attempted to remove it using a boss nut wrench, but this method ultimately proved unsuccessful.

A nylon line was read today after propeller lifting shell fitting and the Boston not wrench was yard and stayed into place. The wrench was then fitted and aligned on to the nut. To attempts to loosen the nut using 20 tons of pull were made counterclockwise, 1 from the one o'clock position and one from the eleven o'clock position. Neither attempt produced any movement. The wrench was repositioned, and a 1.125-inch wire rope was attached from the crane to the wrench. An attempt to tighten the nut by rotating clockwise succeeded in moving the nut circumferentially 1 1/4 inches.

The screw was then positioned with the jacking gear to move the wrench to the 5 o'clock position for a third pull at 100 foot tons. This third attempt was also unsuccessful. Two counterclockwise pulls of 200- 250 foot tons using the 50 ton pnuematic chain fall that was attached to the balance beam failed to move the boss nut at all. Another pull at 250 tons sustained over ten hours failed to produce movement. Several additional pulls were made in both directions at 250 tons but still to no avail.

The final pull was made using the 50 ton pneumatic chain hoist and setting off an underwater explosive charge on the handle of the boss nut wrench. The impact from the explosive charge was intended to provide a shockwave to break the static friction force between the nut and the propeller hub, but failed again to move the boss nut.

A subsequent pierside inspection of the wrench revealed that the extensive pulling force had elongated the wrench's key ways. A further review of the data indicated a strong possibility that the boss nut was galling on the shaft of threads and that subsequent attempts to remove the nut by turning would damage the threads. It was therefore decided to remove the nut by cutting and splitting it using the new Kerie Cable cutting method.

WebMaster Notes: An explanation of the Kerie Cable Cutting System is needed before continuing on to the next Chapter. This system wes developed in England and had never before been approved for US Navy divers' use. The system consisted of a large bank of pure Oxygen gas cylinders, an Oxygen pressure and flow regulator, 100' sections of the cutting cables, a long welding cable, and a 12V car battery. The regulator box was connected to the Oxygen supply, the battery, and the cutting cable. One end of the welding cable was connected to the battery, and the other was taken underwater to the work site. The cutting cables came in 6mm, 9mm, and 12mm diameter sizes and were made up as follows: a standard, mild steel cable was coated with a thin nylon plastic coating to protect the cable. The center of the cable was actually hollow. When the diver was in position underwater, the Oxygen flow was established to the regulator which pumped the Oxygen down the hollow core of the cutting cable. Once Oxygen flow was verified by the diver, the battery was connected to the cutting cable. Touching the end of the cutting cable to the welding cable produced a spark, which ignited the cuttng cable.

Once the cutting cable was ignited, it would burn with the intensity of a magnesium flare, and it would burn constantly and consistently which allowed us to work methodically. The cable was consumed by the burning Oxygen, and the heat produced could cut through 2" of solid plate steel in a single pass. When one cable had burned down to the end, the regulator was shut off and a new cable was attached with work resuming almost immediately. By using the 3 different sizes of cutting cable, we had incredible control of underwater cutting operations- better control than the Navy Divers had ever had before. The system was approved for Fleetwide use after this job. The Kerie Cable would prove instrumental a year later when the Aircraft Carrier USS Kittyhawk CV-63 hit a submerged Ruskiey nuclear submarine, resulting in extensive underwater damage to both vessels. BUT.... that's another story <G>

WebMaster Bruce