# Deep sea cable laying **URL:** \ **Category:** Factual Questions\ **Created:** [August 22, 2005, 9:36pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180 "2005-08-22T21:36:49Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Busy\_Scissors](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@Busy\_Scissors](https://boards.straightdope.com/u/Busy_Scissors)\ **Post date:** [August 22, 2005, 9:36pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/1 "2005-08-22T21:36:49Z")
In submarine telecommunications, does anyone know if the cable actually lies on the sea bed, or is it suspended at a certain depth in the deep ocean? Looking at transatlantic cables, for example, isn’t there a tectonic plate boundary in the middle of the Atlantic that would prevent just laying a cable across it from Europe to North America? Wikipedia has some good pages on the early days of transatlantic telegraph and telephone lines, but I couldn’t find the answer. [In one of the pages](http://en.wikipedia.org/wiki/Transatlantic_telegraph_cable), it talks about the cable breaking as it was being laid down from a ship in the middle of the ocean. The ship called it a day, but later returned to the middle of the ocean to “grapple the cable…after thirty casts of the grapple she hooked and raised it [the cable]” How on earth is this possible (in the 1800s) ? ---
**Author:** ![Tripler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripler/32/21807_2.png) [@Tripler](https://boards.straightdope.com/u/Tripler)\ **Post date:** [August 22, 2005, 11:27pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/2 "2005-08-22T23:27:13Z")
I have never laid oceangoing cable. But I have laid cable here in the States, most recently at my job at Cannon AFB. I will make an educated guess that to install chairs, buoys, or conduit to suspend the cable would be prohibitively expensive for a trans-Atlantic crossing. On land, I’d put cable in conduit to: [ul] [li]Protect the cable from damage[/li][li]Easily replace the cable if something goes wrong (i.e. someone hits it with a shovel or backhoe and breaks it).[/li][/ul] But under the ocean, what the heck is going to hit it, as excavation on land would? My educated opinion, for back then, and for now, is that it’s directly laid on the ocean floor, avoiding known hazards as much as possible. It’s fairly common to manufacture water-resistant insulation for electrical cable, and while expensive, you can manufacture waterproof cable too. I’ve even heard stories about sharks attacking fiber-optic cables for some strange reason. It seems they’re attracted to those same fiber-optic lines. Tripler I’ve concrete-encased some of the “land lines” I’ve laid, just to protect the ‘diggers’. ---
**Author:** ![Tripler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripler/32/21807_2.png) [@Tripler](https://boards.straightdope.com/u/Tripler)\ **Post date:** [August 22, 2005, 11:29pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/3 "2005-08-22T23:29:58Z")
> [@Myler Keogh](#): > > The ship called it a day, but later returned to the middle of the ocean to “grapple the cable…after thirty casts of the grapple she hooked and raised it [the cable]” How on earth is this possible (in the 1800s) ? Oh, and my guess on this one: You run out of line say, 250 miles offshore. You navigate back 10 or 15 miles, and start trawling with a hook perpendicular to the line. Once you get a “hit” (steady tension on the line), haul that hook up and see what you get. Eventually, you’ll get the comm line. Tripler It’s a game of hit or miss. You just gotta narrow your odds. ---
**Author:** ![Burrido](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@Burrido](https://boards.straightdope.com/u/Burrido)\ **Post date:** [August 22, 2005, 11:36pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/4 "2005-08-22T23:36:20Z")
[http://www.oceansatlas.com/unatlas/uses/transportation\_telecomm/marine\_tel/subcables/submarin.htm](http://www.oceansatlas.com/unatlas/uses/transportation_telecomm/marine_tel/subcables/submarin.htm) This site calls them Submarine Cables. According to this site they are buried to a depth of 1 meter when necessary otherwise from what I gather its just laid on the seafloor. > **[Answers - The Most Trusted Place for Answering Life's Questions](https://www.answers.com/redirectSearch?query=submarine-communications-cable)** > > Answers is the place to go to get the answers you need and to ask the questions you want [Answers.com](http://Answers.com) pretty much says the same thing. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [August 22, 2005, 11:42pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/5 "2005-08-22T23:42:48Z")
[Loooong but interesting read](http://www.wired.com/wired/archive/4.12/ffglass.html). ---
**Author:** ![Fuji\_Kitakyusho](https://avatars.discourse-cdn.com/v4/letter/f/f0a364/32.png) [@Fuji\_Kitakyusho](https://boards.straightdope.com/u/Fuji_Kitakyusho)\ **Post date:** [August 22, 2005, 11:45pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/6 "2005-08-22T23:45:04Z")
No suspension. Breaks in submarine cables are simply expected, and planned for. Such cables are generally well armoured by means of a jacket to protect against abrasion, overtension and overbending. Simply dropping the cable on submerged rocks, etc. is unlikely to damage it; however, an enounter with a ship’s anchor, or tectonic activity as discussed in the OP, could definitely sever or damage a submarine cable, and these cables are continually repaired and maintained. The cable is simply lain on the seabed, or in some cases is deposited in a shallow trench dug by a remotely operated vehicle commanded from the cable-laying ship. There are such ships on 24-hour standby to repair any damage to these cables. When this occurs, the ship establishes a position above the break, hooks the cable and brings it to the surface, performs the repair, splice or retermination as necessary, and then lowers the cable back to the seafloor. The ship carries reels of cable on board so even a significant gap can be bridged if necessary. Ship manoeuvering is controlled by a dynamic positioning system, placing the ship’s position, velocity, and track of lain cable, under computer control for high accuracy. ---
**Author:** ![rbroome](https://avatars.discourse-cdn.com/v4/letter/r/838e76/32.png) [@rbroome](https://boards.straightdope.com/u/rbroome)\ **Post date:** [August 22, 2005, 11:57pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/7 "2005-08-22T23:57:40Z")
> [@Myler Keogh](#): > > In submarine telecommunications, does anyone know if the cable actually lies on the sea bed, or is it suspended at a certain depth in the deep ocean? Looking at transatlantic cables, for example, isn’t there a tectonic plate boundary in the middle of the Atlantic that would prevent just laying a cable across it from Europe to North America? > > Wikipedia has some good pages on the early days of transatlantic telegraph and telephone lines, but I couldn’t find the answer. [In one of the pages](http://en.wikipedia.org/wiki/Transatlantic_telegraph_cable), it talks about the cable breaking as it was being laid down from a ship in the middle of the ocean. The ship called it a day, but later returned to the middle of the ocean to “grapple the cable…after thirty casts of the grapple she hooked and raised it [the cable]” How on earth is this possible (in the 1800s) ? I am not in the business, but being in oceanography at least caused me to read various articles on the subject. Full ocean (ie trans-Atlantic or trans-Pacific) cables are laid on the bottom in deep water. In shallow water where ship’s anchors might interfere they are buried. Pipelines are always buried (well they should always be buried. But it can get difficult and expensive). Hazards to cables come in many forms. There are documented cases (I have read) of Sperm whales becoming entangled in undersea cables 1000’s of feet down. Usually it is simply a failure of one of the repeaters (the cables have electronic repeaters inline with the cable every few miles. Boosts the signal to keep things reliable) but it could be lots of things. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [August 23, 2005, 3:35am UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/8 "2005-08-23T03:35:05Z")
> [@Balthisar](#): > > [Loooong but interesting read](http://www.wired.com/wired/archive/4.12/ffglass.html). I’ve read and reread that story several times in the past, and it was my first thought after reading the thread title. Thanks for the link, but sorry you beat me to it! ---
**Author:** ![Busy\_Scissors](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@Busy\_Scissors](https://boards.straightdope.com/u/Busy_Scissors)\ **Post date:** [August 23, 2005, 11:17am UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/9 "2005-08-23T11:17:27Z")
Thanks for the answers and some great links. > [@](#): > > Oh, and my guess on this one: > > You run out of line say, 250 miles offshore. You navigate back 10 or 15 miles, and start trawling with a hook perpendicular to the line. Once you get a “hit” (steady tension on the line), haul that hook up and see what you get. Eventually, you’ll get the comm line. > > Tripler > It’s a game of hit or miss. You just gotta narrow your odds. That makes sense **Tripler** , although I guess my question was more about navigation. The ship broke the cable \*ca \*1000 miles from shore, in mid ocean. It didn’t return to retrieve the broken cable until the next year, in 1866. Given that the cable is of the order of 1m wide, it seems an astounding feat of navigation (for 1866) that the ship can return to the middle of the atlantic with a big hook and just fish the thing back out. ---
**Author:** ![flurb](https://avatars.discourse-cdn.com/v4/letter/f/51bf81/32.png) [@flurb](https://boards.straightdope.com/u/flurb)\ **Post date:** [August 23, 2005, 2:07pm UTC](https://boards.straightdope.com/t/deep-sea-cable-laying/318180/10 "2005-08-23T14:07:10Z")
Additionally, how were they able to figure out where a break had occurred in the line back in the 1800s?