The Tacoma times. [volume] (Tacoma, Wash.) 1903-1949, 1940-06-20

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direct, and hence greater. pur-
chase: the twisted rudder merely
straightens the stream again and
makes the whole project literally
stream-lined
or. to say il differently, the
entire underwater portion Of the
ships after end is a type OF n.y.
draulic turbine in principal
Ships of Yesterday had pad
dle-wheels. Ships of Today have
screw propellers. ships of To-
'morrow will have the contra
rudder and stern. See:
Because all of the vessels built
by the T. s. maritime commission
are designed as naval auxiliaries,
speed is big factor
Tank-models of the contra stern
show more than so per cent eff
cheney per power applied-remark-
ably high.
incidentally. the contra stern Is
responsible for the unusually good
and easy speeds of the Stag Hound
and Flying Cloud. only commission
ships which have visited the North
west and which set waterfront
tongues wagging about their mys-
FERROUS speed and great potentisli-
ties. Thus, in practice il measures
to theory
Now the construction Of the
contra stern is a yarn of indus
try mt It's best.
The stern frame-which is simp-
ly the metal part where the rudder,
propeller and hull meet weighs
nearly 40 tons alone.
1t is cast in four pieces in Cali
fornia. then brought TO the Pacific
Iron & Steel company's plant here
for machining and assembly.
Except for its magnitude. the
job is as precise as matchmaking.
In order to machine the huge
pieces they must be perfectly
aligned. So the shipyard's own sur
veyor does it with transit and
plumb-bob!
The four parts, when machined
and polished, are fitted together
and welded. The finished stern
frame is seen in the photograph.
Next comes the building of the
25-ton rudder. It's hollow except
of course, for myriad of steel
bracing, inside paint; it's made
entirely of steel, both castings and
plates.
The four-bladed, one-piece cast
propeller, however, is made in
Seattle foundry. 1t weighs approx
mately 10 tons.
Last, but not least, of the Paci-
fic Iron & Steel company's jobs
for the ships is finishing the cast
ing which is the stern tube, or
after shaft bearing.
Made of steel a foot thick, it's
the baby, weighing only above five
tons. According to our measure
ments as it lay on the foundry
floor, it's seven PAGES long and
waist high.
General Superintendent Albert
Worley says people who take a
quick, haphazard peek at the stern
tube and yell that Pacific Iron g.
Foundry is turning out cannons-
well not exactly crazy, but you
get the idea)
Bearings for the tube and the
rudder are big item and are also
made there. The rudder's gudg-
cons and pintles seat to new
product called Micarta, which is
self -lubricating in water. some
thing like bakelite and developed
by Westinghouse. The propeller
shaft rides in the stern-tube upon
lignum-vitae wood, of which the
foundry has Just acquired several
beautiful logs to be cut into proper
blocks.
In any event, you can readily
see that the underwater stern
assembly OF the five 415-foot
ships Is not child's play in any
phase.
And there's another noteworthy
chore in which Pacific Iron & Steel
participates in shipbuilding tSu-
perintendent Worley put in six
years as marine engineer-he's
having the time of his life these
days.)
The steel stems Of the big ships
weigh nearly six tons each. They
are very swsgger. rakish, stout
and also stream-lined.
But most interesting feature Of
them is the unobtrusive hook right
at the vessels forefoot.
II is a grim reminder that com
mission-built ships are for use as
naval auxiliaries in time Of emer-
gency. To those hooks will be
fastened parsyane wires-for mine
I supaar4no