[ham-hist] undersea cables

[Jeffrey Herman]

What a coincidence -- I just finished reading a neat little book,
"Voiceway To The Orient, First US-Japan Telephone Cable." Sixty
pages of very fast reading, with lots of great photos of: AT&T's
"Cable Ship Long Lines,"  the cable being manufactured, how it was
stored on the ship, the 12-foot drum engines which paid out the
cable to the deck, the linear cable engine which pulled the cable
and spliced-in repeaters from the ship's hold, splicing techniques,
insides of the repeaters.

The book describes the trouble laying a cable across the Pacific --
the deepest undersea trenches are located in this ocean; for example,
the Marianas Trench's deepest spot is 35,800 feet, or 7 miles!!!

Beginning three years prior to laying the cable, survey ships were
dispatched to find the most economical route. The Pacific had not
been well charted, so the route was found by trial-and-error. Land
bridges were searched for every time a deep trench was encountered.
The path chosen went from Oahu to Midway Island via the Hawaiian
Undersea Ridge, through the Emperor-Seamount Chain, the Marcus-Wake
Seamounts, then Wake Island, through the Magellan Seamounts, skirting
the Marianas Trench, Guam Island, then along the South Honshu Undersea
Ridge, skirting the Bayonesu Retsugan active undersea volcano, skirting
the Iwo Oshimo active undersea volcano, finally reaching Sagami Bay in
Tokyo. (During the survey it was discovered that Sagami Bay had dropped
600 feet due to an earlier earthquake. All cables within the bay had been
severed from that quake.)

The cable project cost $80M (1964 dollars). The cable would have to
withstand 12,000 pounds per square inch, and would contain a tube
amplifier ("repeater") every 20 miles. Each repeater was designed to
operate for 20 years; each cost $60,000; each required 63 weeks to
construct; each contained 6 tubes, 58 capacitors, 48 inductors,
3 gas tubes, 6 transformers, a crystal unit, "...as well as the
thousands of other parts"; in the construction of the repeaters,
more than 1500 X-rays were taken each month to spot flaws. "Each
of the six electron tubes that goes into the assembly undergoes
2,978 separate tests, lasting nine months. Four out of every five
tubes don't pass." (Wonder what tubes were used? 20 years?)

A chapter was devoted to discussing armored versus armorless
cable (this was the first use of armorless cable).

The take-off point from Hawaii was located at Makaha Beach on Oahu
(next time I'm on that side of the island, I'll have to look for
terminal building!).

Getting the cable ashore is done with divers: "From the beach,
skin divers in scuba harness swim toward the line of breaking
surf which the landing craft cannot pass. They tow a hawser
attached to a winch on the beach. Once the swimmers are past
the breakers they meet the landing craft, the hawser is attached
to the cable, and the winch draws it in." It's supported by
inflated balloon buoys. The technicians in the "splice pit"
then join the cable to terminal building equipment.

Louis Solomon is the author is this fine little book.

Jeff KH6O

P.S. I love our U.H. research library! It contains a life-time of
reading projects for me.

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