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Undersea Cable Repair Via 19th Century Tech

Posted by ryuzaki0 on from the going-old-school dept.

An anonymous reader writes to mention a story going across the wires about an old-fashioned way to fix a modern convenience. Taiwanese boaters are using simple hooks to fish up the fiber-optic cables damaged in an earthquake late last year. The outage that resulted kept millions of users offline in half a dozen countries around the Pacific rim. From the article: "They work 24 hours a day but the weather can hinder their progress. Walters said one ship is waiting for 30 to 40 mile-an-hour winds (48 to 64 kilometres- an-hour) to die down in the Bashi Channel. The winds have stirred up 10 to 12 metre waves ... After arriving at the scene they survey the ocean bottom to assess whether the contour has changed, and the degree of sediment movement. Then the traditional tools are brought out. A rope with a grapnel on the end is played out, down into the depths, and towed over the sea floor until tension registers on a graph on the ship, indicating contact has been made with the cable. Today's fibre optic cables are just 21 millimetres in diameter."

26 of 98 comments (clear)

  1. 21 mm? by JeffSh · · Score: 3, Interesting

    Correct me if I'm wrong, I'm no expert on this subject, but undersea cables certainly aren't 21 mm wide. Certainly they are run in bundles of dozens (maybe hundreds) for a total width of several inches. At work we had fiber cable installed that has 16 or so strands and it was half an inch thick.

    I guess it's just bad writing and I shouldn't be so nitpicky. :)

    1. Re:21 mm? by PerlDudeXL · · Score: 2, Informative

      21 mm == 2,1 cm (which is more than half an inch)

      But I can image that those fibre cables are bundled and come with a undersee resistant coating.

    2. Re:21 mm? by Bios_Hakr · · Score: 4, Informative

      The don't just have fibers either. There is a central core; usually steel cable. Then they have power feeds for the repeaters. Every 50~100km, they'll have a repeater pod. Finally, they have the fibers and, on top, a thick metal or plastic sheath.

      What's really amazing about undersea cables is that no one outside the industry really thinks about them. Sprint and ATT give everyone the impression that sats take care of most comms. However, the opposite is mostly true. The vast majority of comms are way too time sensitive to allow the the delay imposed by satcom.

      --
      I'd rather you do it wrong, than for me to have to do it at all.
    3. Re:21 mm? by Anonymous Coward · · Score: 4, Insightful

      What's really amazing about undersea cables is that no one outside the industry really thinks about them.

      That's the way any engineering works if it is well designed. Most people don't think too much about how a hydroelectric or coal power plant works either. Nor do most people today care about how an interrupt controller works.

      It sort of sucks for the engineer because you are in the position where you are only recognized if you frack up (and yes I've been in BSG withdrawal). The best type of award you can get for your accomplishments (other than a big fat paycheck) is for nobody to ever think about what you did. Case in point: everyone remembers the dipshit who invented the square wheel, but nobody ever gives recognition to the genius who invented the round wheel.

    4. Re:21 mm? by TheCybernator · · Score: 3, Informative

      Today's fibre optic cables are just 21 millimetres in diameter. what author probably wants to highlight is that today's ONE optic cable is 21mm thick. Nowhere its mentioned how many cables are lying out there. May be they wont want to reveal it either.
      But given the bandwidth capacity of the routes, we should be able to find it. It cant be rocket science in undersea anyway.
      --
      Eclipse PDE and Me
    5. Re:21 mm? by grementas · · Score: 3, Informative

      Actually, there is also a 17mm version of the cable. Those diameters are for the cable used in the deep-sea portion of the cable system. Any cable layed near shore has additional "armoring" layers of steel wires to protect it from anchors and what not. This armoring brings the diameter up substantially. By the way, there are only either 4 or 8 fibers pairs in a single cable. Even so, these systems transmit incredible amounts of information (10GB/s) per fiber pair. You'd be amazed at how many of these systems are in the water. http://www.tycotelecom.com/SystemSupply/content.as p?page=subSystems.asp

    6. Re:21 mm? by StikyPad · · Score: 3, Interesting

      There's tons of information widely available about undersea cables, if one cares to look. In general, though, they just lay one cable at a time, and only lay a new one when capacity is getting low. This may be surprising, but even a 2.1cm cable takes up a lot of room on a ship when it's 10,000 miles long.

      --
      https://www.eff.org/https-everywhere
  2. Did I just get FP? by OmnipotentEntity · · Score: 3, Interesting

    Anyway, with all this wind and water moving, how do they find a 21mm cable 2.5 miles down? A rope that far would bend under air resistance, let alone water resistance. I think some high technology went into this somewhere. Kudos on not making it too complicated. KISS at work.

    --
    "Build a man a fire warm him for a day, set a man on fire and warm him for the rest of his life."
  3. huh by mastershake_phd · · Score: 3, Insightful

    They can find a cable using just a rope and a hook. And shipwreck hunters with modern equipment have a hard time finding ships when they know where they went down.

    --
    Libertarian Leaning Political Discussion Forum.
    1. Re:huh by amorsen · · Score: 5, Interesting

      It's reasonably easy to find a cable. At those depths the cables lie directly on the sea floor, and if you run a hook across the sea floor from one side of the cable to the other, you'll cross it by definition. Sure you might then end up some distance from the break, but they are apparently reasonably good at handling that. Such techniques don't work with shipwrecks -- and even if they did, there may not be anything the right shape for a hook to catch.

      Anyway, there's an old but interesting article on undersea cables by Neal Stephenson.

      --
      Finally! A year of moderation! Ready for 2019?
  4. Get with the program by dangitman · · Score: 4, Funny

    What, are they Amish or something? Every modern company uses sharks with friggin' lasers to repair optical cables.

    --
    ... and then they built the supercollider.
  5. No Electronics? by SageMusings · · Score: 5, Informative

    I beg to differ. There are devices known as OTDRs (optical time-domain reflectometers). Essentially, you shoot a pulse of light down the carrier and start a high-speed counter. The difference in refraction (say, a break in the cable or the end of the cable) causes a reflection that is detected at the device. Using the elapsed time, you get the distance to the break.

    Check out this link http://en.wikipedia.org/wiki/Optical_time_domain_r eflectometer

    I also saw a documentary on the Science channel about these ships. The whole process of fixing the break is sterile and professional. They use fusion splicers, which fuse the two ends with an electric arc. Fascinating stuff.

    --
    -- Posted from my parent's basement
    1. Re:No Electronics? by rjforster · · Score: 5, Insightful

      Disclaimer: I used to build the pump lasers for the submarine repeaters so I know something about this. I also have a fibre optics PhD and have made more fusion splices than I care to count.

      OTDR only works if there are no isolators in the path. (Gizmos which let light pass in one direction only)

      In some submarine cable designs at each repeater there is a return path (ie a fibre loops back) going back the way the light came. I seem to remember this being at an out of channel wavelength (so it passes through some wavelength dependent isolators). Anyway, once you know how many repeaters you do get light back from along this return path you know more about where the break is.

      I was surprised by the comment about the cable thickness for working at 2.5 miles depth. The repeater chassis I've seen are steel, coffin sized, and the walls are 21mm thick.

      I also have a feeling that todays technology is the same as that of 4 or 5 years ago. There hasn't been that much investment (or new jobs) in new submarine cable tech since the dot-com crash. Maybe it's picking up again now but it will take a while to get the momentum back that we had in the R&D team 6 years ago.

    2. Re:No Electronics? by mike_in_nj · · Score: 4, Interesting

      Disclaimer: My father worked for several firms involved in the manufacture, laying, and operation of submarine cable systems in the 80s and 90s. I've seen and handled the cables and have toured the type of ship shown in the photo.

      The cable size (21mm) sounds correct. They are much smaller than the repeaters. I've seen some samples mounted on display plaques so that you can see how they are constructed. Each cable contains a small number of tiny fibers (the ones I've seen had 6). The construction is a solid metal (steel?) core for strength, then some sort of thicker plastic layer around it that contains the fibers embedded within it, then a copper shield layer, and then more of the plastic material. I've probably missed a layer or two.

      On the deep sea floor, that's all there is. Just one of those cables (not bundled or armored) with the big repeater casings every so often. At shallower depths, they can be armored to prevent damage from sharks. (Sharks like them, don't know why.)

      The ships are pretty amazing. They have large bow and stern thrusters and can hold position in some pretty rough water. They have huge, round vertical cylindrical holds into which the cable and inline repeaters are fed in and spooled from the factory, and then fed back out when laying them at sea. There's a giant conveyor mechanism that runs from bow to stern to facilitate deployment or recovery of the cable and repeaters. This conveyor clamps onto the cable from above and below it, but it can also widen dramatically to accommodate the repeaters as they pass through.

      Interesting that they use a line and a grapple to find and recover the cable, but they do have very precise survey maps to work from that were created when the cable was originally laid, so they probably don't have to look very far to locate it.

    3. Re:No Electronics? by tuxicle · · Score: 3, Insightful

      Sharks like them, don't know why Sharks sense electric potential generated by their prey through receptors on their nose, maybe they detect the fields from the power feeds for the repeaters?
    4. Re:No Electronics? by Dr_DTHP · · Score: 2, Funny

      Disclaimer: I am an undersea fiber-optic cable.

      All of the above opinions and bits of information on me and my kind are completely incorrect. I am insulted!

      Take that, progressively-more-expert-series-of-experts!

  6. Had to be said by elecwolf · · Score: 2, Funny

    I thought modern browser technology was supposed to prevent fishing?!?!

    --
    David 'Volk' Mc. Itazura!
  7. Actually... by kamapuaa · · Score: 4, Informative

    Actually, it didn't keep people offline in Asia. It just made international Internet connections incredibly slow. Using the Internet for national sites, which is the vast majority of Internet use, was barely effected. Here in China, nobody at my American-owned computer company even cared, except that MSN chat was pretty spotty for a couple days.

    --
    Slashdot: providing anti-social weirdos a soapbox, since 1997.
    1. Re:Actually... by Vinegar+Joe · · Score: 2, Informative

      Uh......friends of mine in Shenzhen were unable to send or receive email for a week and today I was *finally* able to make a call to Indonesia from Taipei. Many, many websites in the US simply timed out. Things are finally getting back to normal.

      --
      "The average reporter we talk to is 27 years old......They literally know nothing." - Ben Rhodes
  8. Re:Metric / Imperial by FireFury03 · · Score: 3, Insightful

    And weird E and R switched in meter metric!

    Meter == device for measuring stuff. I.e. volt meter, etc.
    Metre == measure of distance (the distance travelled by light in absolute vacuum in 1/299,792,458 of a second.)

    Just because Americans can't spell doesn't mean the rest of the world has to adopt your broken spelling.

    --
    http://blog.nexusuk.org
  9. And what exactly would be a modern way? by Josef+Meixner · · Score: 5, Interesting

    When a method works well, there is not really a need for something else, it will only be used when it is superior. So what would those alternatives be, that are cheaper overall?

    A submarine robot repairing on site is probably not possible (I have problems believing it would be able to fuse the fibers), so you only could use it to more quickly find the cable and perhaps make it easier to get the hook onto it as you can see what you are doing. But honestly, how much faster would it be, I guess a hook and the cable for it can just be tossed into the water, an expensive robot probably would take a bit longer to reach the ground. And it probably has limitations on the depth it can operate. Additionally I am quite sure they don't just drive out there and plow the sea bed, they probably have a very good idea where the cable is supposed to be. And don't forget, to find a very long cable is much simpler than finding a wreck. I don't have to find a particular piece, any piece before and after the break is ok, as I can just pull the part up and then follow it, no need to exactly grab the end.

    Also the strong winds and high waves probably would make fusing the cables very hard as well, even if they could bring up the cable. So the only thing 'old fashioned' I can see is, that they use a hook. The rest is probably quite up to date and the hook is simply the easiest, most reliable and cheapest way. Why use expensive technology if something simple is perfectly adequate?

  10. Is this newsworthy? by andrewdotcoza · · Score: 4, Insightful

    I don't want to seem overly flippant, but is there really something significant about mariners using hooks to pull stuff out of the sea? I'm not really clear what the alternatives were. I'm expecting "Man Digs Hole With Spade" and "Tech Professional Presses Distant Button With Pointed Stick" as future headlines. OK. I admit that was overly flippant.

  11. Re:Metric / Imperial by IDK · · Score: 2, Informative

    Another, related thing:

    I don't know how americans mesure winds, but here in Sweden we always mesure them in m/s, and nothing else.

    48 to 64 kilometres-an-hour would then be 13 to 18 m/s

    And that doesn't seem to be very much, now(saturday morning) the winds at the coast where I live are 18-22 m/s, and it isn't even very much.

  12. -er / -re by Atario · · Score: 3, Funny

    So then we can assume that:

    Theater == facility for viewing movies, plays, symphonies, etc.
    Theatre == the drama and spectacle on display in a theater

    Pepper == a spice
    Peppre == the hot sensation you get by eating pepper

    Jester == comedic performer in medieval times
    Jestre == the jokes and skits he performs

    Adapter == Device which connects two things which otherwise wouldn't
    Adaptre == The quality of the connection being changed (e.g. gender, voltage, diameter, etc.)

    Diameter == Device for measuring diametre
    Diametre == Distance across something round

    Hm, wait a sec...

    --
    "A great democracy must be progressive or it will soon cease to be a great democracy." --Theodore Roosevelt
  13. How to repair deep sea cables? by Eravnrekaree · · Score: 2, Interesting

    Ive always wondered how, or if, they repair cables which are located several miles underwater and continue for a thousand miles. How would you ever hook onto such a cable, and pulling it to the surface seems rather difficult to me and would put a lot of stress on the cable. I just assumed if the cable went bad, they would have to lay all new cable.

  14. Sophisticated Grapnels by lahosken · · Score: 2

    I read a book from 1896, Wilkinson's Submarine Cable Laying and Repairing. I was pretty impressed with the complicated grapnels they had back then--capable of scooping up a delicate cable, slicing the cable as appropriate. I was so impressed that I typed up the grapnel chapter, scanning in the illustrations: http://lahosken.san-francisco.ca.us/frivolity/wilk inson/I_3.html