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Date: 18-Jul-1986 1346
From: covert%covert.DEC@decwrl.DEC.COM  (John R. Covert)
Subject: Just when AT&T thought it was safe to go back into the water

>From the Wall Street Journal, 26-June-86, included without permission.

Survey:  Sharks Prefer AT&T Lines By Wide Margin Over Sprint, MCI
------   ------ ------ ---- ----- -- ---- ------ ---- ------- ---

			By Bob Davis
	Staff Reporter of The Wall Street Journal

Just when American Telephone & Telegraph Co. thought it was safe to go
into the water, sharks began dining on its newest undersea
telephone-communications cable.

It seems the sharks just can't get enough of AT&T experimental
underwater fiber-optic telephone cable near the Canary Islands. They
munch on its plastic covering, gnaw on its electrical innards and
eventually short-circuit it-even though they may electrocute
themselves in the process.  At least, "we came up with some pretty
effective shark bait," says an AT&T spokeswoman.

At first, AT&T engineers didn't know what was causing the cable
failures.  Then they raised the cable and found rows of shark teeth
sticking out of it.  "Sharks will always be attracted to magnetic
fields," which the fiber-optic cables create, says James Barrett, an
AT&T engineering official.

		Transatlantic Race

That's the big problem because AT&T is hurrying to complete the
world's first transatlantic fiber-optic cable by 1988. The cable uses
glass fibers instead of copper wires to transmit conversation and
data.  AT&T's old cables generally are shark- free because they don't
emit much magnetism.  But a shark bite helped knock out the Canary
Island fiber-optic cable for a full week.

AT&T says it can combat the sharks by reinforcing stretches of the
cable with steel wire and quickly patching breaks that occur. But the
company's shark problem has attracted another kind of predator.

		Space Shark

Communications Satellite Corp. (Comsat) a Washington, D.C., satellite
company, is pressing Congress to spend $119 million next fiscal year
on a new satellite system that will compete with fiber optics.
Meanwhile, Comsat officials are turning AT&T fish difficulty to their
own advantage: Shark attacks "may cause a delay of six months to a
year," in laying AT&T's transatlantic cable, asserts John Evans, a
Comsat vice president.

AT&T denies any such delay.  And even Comsat's lobbyist, Thomas
Scully, doubts that Congress will swallow the fish story.

He reasons: "If I were at AT&T and I saw an article saying the biggest
problem facing fiber optics is that fish eat the cable, I'd say, "Boy,
the satellite people are desperate."

		-30-

Notes: The person from whom I originally received this article was
immediately sceptical of the reports of magnetic fields from fiber
optic cables.  But unlike short-haul terrestrial fiber cables, where
the fiber would not emit any fields, undersea cables must carry high
voltage power to the undersea repeaters, which would result in both
electric and magnetic fields around and along the cable.

The article is further misleading in stating that old cables are
shark-free because they don't emit much magnetism.  It appears that
the real reason here is more likely to be because the conventional
cables are a larger diameter which the sharks can't so easily get
their teeth around.

And finally, experiments have shown that sharks are attracted to
electrical fields which many of their prey emit.  There is little to
no data about magnetic fields and shark.  I have, however, read
articles about other animals using magnetic fields for navigation.

/john

From: nagle@netcom.com (John Nagle)
Subject: Re: AT&T Ship Sets Trans-Oceanic Cable Installation Record
Date: Mon, 11 May 92 07:48:04 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 

dag@ossi.com (Darren Alex Griffiths) writes:

> Some of the things I'd be interesting in hearing about include how the
> cable is spliced together. I assume that the ship didn't have 3,250
> miles of continuous cable on a big spindle. 

       No, they actually do carry enough cable to do the whole job.
Cable is carried in big round holds, but they don't rotate; the cable
is pulled out layer by layer from the top, having previously been
carefully loaded in port.

       Splices between sections are done on shipboard when necessary.

       The cable isn't just dropped overboard; the ship tows a heavy
plow that makes a furrow and buries the cable, at least in areas where
other ships are likely to be dragging anchors.


John Nagle


From: floyd@hayes.ims.alaska.edu (Floyd Davidson)
Subject: Re: AT&T Ship Sets Trans-Oceanic Cable Installation Record
Organization: University of Alaska Institute of Marine Science
Date: Mon, 11 May 1992 01:47:06 GMT

In article <telecom12.378.10@eecs.nwu.edu> dag@ossi.com (Darren Alex
Griffiths) writes:

> questions.  If someone in the know can spend some time letting us know
> more details about the techniques used to lay trans-oceanic cables, or
> point to a good reference source, I'd appreciate it.

> Some of the things I'd be interesting in hearing about include how the
> cable is spliced together. I assume that the ship didn't have 3,250
> miles of continuous cable on a big spindle. Does another ship provide
> additional cable every mile or so?  How do they lay a cable part way?
> I assume that if it's half way across the Pacific they don't simply
> let it drop to the bottom and hope they find it again. Is it anchored
> to a buoy?  Finally, what if the cable develops problems; can they go
> down and fix it and is the topology of the ocean floor and the depth a
> serious concern?

I know just a little bit.  I've seen sample pieces of the North Pacifc
Fiber.  The topology is of considerble importance, and the differences
in types of cable are good indicators.  Some of the cable is as small
as about 1 inch in diameter (most of which is sheathing for protec-
tion).  It gets larger and larger depending on how much armor is added!
There are five or six different sizes in use.  At the point where it
comes on shore it is about five inches, and the added part is almost
all steel armor.  That portion is also buried.

The North Pacific Fiber is presently being repaired due to problems
just off the Oregon coast.  I could guess at various ways they might
locate the cable, but I really don't know what they do to find it.  I
do know that it is located and hauled up very quickly.  My
understanding of the current situation is that it is up on three
buoys, they have replaced one repeater and spliced in some new
cable ... and it was supposed to go on line Friday night but it did
not pass a 24 hour bit error rate test.


Floyd

From: nagle@netcom.com (John Nagle)
Subject: Re: Britain-Japan Fiber Cable
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
Date: Thu, 29 Dec 1994 17:40:03 GMT

wrf@ecse.rpi.edu (Wm. Randolph U Franklin) writes:

> AT&T will build a cable from Britain to Japan for $1.2G.  It'll be
> 17,000 miles long, 5Gbps, and carry 320,000 "voice and other messages".  
> That looks like only 16Kbps per circuit (which looks low).  The
> current longest cable is a 9,000 mile one from France to Singapore,
> completed a year ago.

> Fun math: That works out to a capital cost per circuit of only $3750.
> Assume that a phone call from Britain to Japan costs $2/minute.  If
> all 320,000 channels were in continuous use, then the cable would be
> paid for in the first 31 hours.

> Alternatively, if we assumed that the cable is good for ten years,
> or 100,000 hours, then amortizing the capital cost would be three
> cents per hour, or $5e-4/minute.  This is a factor of 4,000 less
> than the price of the call.

      The numbers for the newer transantlatic cables look like that,
too. You really should be able to buy a full-time transatlantic
circuit for about $100/month, and at the rate cable is being laid, you
probably soon will.

      Not having to acquire property rights is a big win. Fortunately, 
the UN didn't think of this for the Law of the Sea conference.


John Nagle
      

 



































































































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