8 SALVAGE EQUIPMENT USED IN RAISING SUBMARINE F-4. 
In order to provide a margin of reserve power for starting the vessel, provi- 
sion was made for using the buoyancy of the scows. A flood valve was fitted in 
the bottom of each scow and pumps were installed on deck for unwatering. Sta- 
bility calculations indicated that the scows would be unstable with the load sus- 
pended from the windlass shafts because of the internal free water sur- 
face. In order to counteract the upsetting moment due to the negative meta- 
centric height under these conditions, should it become necessary to flood the 
scows, heavy timber cribbing was fitted around the bottom of the mud-pockets 
for restricting the swing of the lifting hawsers. This timber cribbing also 
served the purpose of protecting the structure of the scow itself from the cables. 
The cribbing consisted of 12-inch by 12-inch Douglas fir timbers. It was found 
necessary to flood a scow only once—to relieve the strain on a jambed hawser. 
Figs. 1 and 2, Plate 4, show some of the details referred to above. 
LIFTING HAWSERS. 
Six cables as follows, each from 900 to 1,000 feet long, were used for lifting 
at one time and another :—one 25-inch plow steel, one 2-inch plow steel, two 214- 
inch galvanized crucible steel, and two 2%4-inch galvanized crucible steel hawsers. 
The two plow steel hawsers, especially the 254-inch hawser, proved the most 
satisfactory, because they resisted chafing to a much greater degree than galva- 
nized wire. On the other hand, the plow steel cables were much harder to handle 
and to sweep because of their stiffness. Splicing the plow steel cables proved quite 
difficult, much more so than splicing the galvanized cables. The 254-inch plow 
steel cable showed a somewhat greater tendency to strand at the windlass shafts, 
due to the short nip, but the stranding was not sufficient to cause the cables to part 
at the upper end. 
The hawsers were attached to the windlasses by means of 2%4-inch hook bolts. 
These hook bolts were fitted through holes drilled in the shafts close to the bear- 
ings, as will be noted from the plans and photographs. By setting up on the nut 
of the hook bolt the hawsers were squeezed down on the shafts and thus kept from 
slipping by friction. The hawsers were further backed up by two cable clamps se- 
cured close to the hook bolts. On several occasions the hawsers started to slip 
through the hook, but held as soon as the cable clamps took up. Three dead turns 
of the lifting hawsers were allowed before taking up the load. 
DREDGE USED AS WORKING BASE. 
On account of the great depth of water, it was impracticable to anchor the 
scows over the submarine while securing the lifting slings to the windlasses. Also, 
the scows did not have on board a power plant and other facilities for taking care 
of the small jobs constantly arising. It was therefore necessary to have a well- 
equipped wrecking craft anchored in the immediate locality of the vessel which 
could be used as a base for conducting the salvage operations. A dredge equipped 
