24 LAUNCHING OF SHIPS IN RESTRICTED WATERS. 
discoloration on the tops and bottoms of the grooves about half an inch wide 
and 20 to 24 inches long. The concentration of pressure and the resultant gener- 
ation of heat were almost sufficient to make the metal soft enough to flow. The 
same condition on the other brakes indicate that the water-cooling features of the 
brake must be improved somewhat and that the cooling must be most efficient 
where the greatest amount of heat is generated. The operation of all other parts 
of the brakes left nothing to be desired. There was no serious twisting of any of 
the cables; for instance, one wire of No. 1 port brake slid for about 280 feet in its 
groove with no such effects whatever. Flats were worn on the outside strands 
and there was some discoloration of the metal, but the cables, after launching, 
were in perfect condition for use on the next battleship. 
“Six of the broken links from the ten chain cables were recovered, and every 
one showed either faulty weld or very inferior structure. On one link the weld 
was perhaps less than 10 per cent effective, and on another there were crystals of 
metal three-eighths inch square. It is not likely that any one of these six 
cables pulled even its normal load of 30 tons, to say nothing of withstanding its 
proper breaking load of 83 tons. 
“The fact that two of the cables broke before 600 pounds pressure had been 
applied to the brakes proves that neither excess load nor sudden application of 
load was responsible for the failure of the chains in this instance. The motion- 
picture records show clearly that the cables remained fairly taut and that there 
was almost no surging for the time that they remained intact. There was no 
apparatus at Mare Island with which to make physical test of these chains, and 
it is quite probable that even such tests, carried only to the proof strength of the 
chain, might not have disclosed serious defects. Chain cables for this purpose 
are considered treacherous and unreliable and far inferior, except for ease in flaking 
down, to wire ropes with suitable end fastenings. They have not been used in 
the past at this yard, and they will not again be used in the future. 
‘Although in this case the absolute failure of these chains to stand up to their 
work introduced some unforeseen. complications, it is considered that the results, 
taken all in all, most fully justified the modifications which had been made in the 
original design of these friction brakes. It is interesting to note from the curves 
that, had the cables held and exerted their proper pull, the vessel would have 
been stopped in almost exactly the same distance as had previously been 
calculated.” 
An examination of Plate 9 will indicate that some of the chain cables in 
question carried away before the defective links had suffered any deformation 
whatever. As an extreme example, it may be seen that the weld on the end link 
of No. 1 port cable opened out as if it had been simply bent to shape and never 
welded at all. 
Aside from the question of chain cables, the functioning of the hydraulic 
brakes was, on the whole, so satisfactory that they will be retained in practically 
their present form for use on the battleship Montana, now under construction at 
the Mare Island Navy Yard. Two additional brakes are to be fitted, making a 
