10 SALVAGE EQUIPMENT USED IN RAISING SUBMARINE F-4. 
what delayed by the weather, but this was finally accomplished and another lift was 
made. A hawser again parted and could not be immediately replaced on account 
of bad weather. While the scows were riding out the weather, one cable after 
another parted, the last to go being the 25¢-inch plow steel cable. Altogether a lift 
of 25 feet was accomplished with the wire hawsers. 
CHAIN SLINGS. 
In view of the rapid impairment of the cables by chafing, a 15-fathom shot of 
chain was next inserted in the middle of each sling where it passed under the sub- 
marine. For this purpose 25£-inch stud link anchor chain was used. The broken 
hawsers were used for the pendants of the slings. Considerable difficulty was ex- 
perienced in sweeping the combination chain and wire slings into place, partly be- 
cause the position of the submarine had been shifted and it now lay with one pro- 
peller buried in the sand. After working twenty-one days all four slings were 
again in place and lifting operations were resumed. 
Good progress was made in hoisting and towing to shallower water. A depth 
of 50 feet was reached close to the harbor entrance, when a heavy ground swell and 
bad weather set in very suddenly and wrecked the whole operation. In order to 
save the scows from being washed up on the reef the hoisting slings had to be 
cast off and the scows towed into the harbor. After a number of days the sea 
calmed down sufficiently to permit divers to examine the vessel. They reported 
that the shell had collapsed in the wake of the former position of the forward slings. 
This was caused by the violent surging of the forward lifting scow in the surf 
waves just before the slings were cast adrift. 
On taking into consideration various phases of the situation, it was decided to 
change the plan of operations. In the first place, the months of June and July are 
the surf months on the south side of the Island of Oahu. A heavy swell can, there- 
fore, be counted on most of the time during these months, off the entrance to Hono- 
lulu Harbor. It was considered likely that new lines could not be placed under the 
submarine and taken to the scows in the short intervals of smooth weather. This op- 
eration, from previous experience, was apt to take a number of days, hence there 
was danger of getting caught suddenly at any time as before. 
The strongest reason, however, for changing the salvage plan was that the sub- 
marine might break in half while being taken through the channel, if lifted by the 
scows. This would have blocked the harbor to navigation. To have attempted re- 
pairs to the ruptured section, in order to permit using the former method of lifting, 
would have involved great expense and much delay, with no assurance of success. 
The work would have had to be done by divers and would have been made exceed- 
ingly difficult by the undertow. 
There was no water shallower than about 40 feet in which the vessel could be 
landed. This was the governing factor in planning the new salvage method. The 
maximum draught which the floating dock in Honolulu can take is about 25 feet 
