One day, you see an ad in a magazine for a newfangled thing called a modem. You hook one end up to a computer and the other end to a phone line, and it enables the computer to grab a circuit and exchange data with some other computer with a modem. So far, so good. As a cable-savvy type, you know that people have been hacking cables in this fashion since Kelvin. As long as the thing works on the basis of circuits, you don't care - any more than a car salesman would care if someone bought Cadillacs, tore out the seats, and used them to haul gravel.
A few years later, you hear about some modem-related nonsense called the World Wide Web. And a year after that, everyone seems to be talking about it. About the same time, all of your traffic forecasts go down the toilet. Nothing's working the way it used to. Everything is screwed up.
Why? Because the Web is asymmetrical. All of your Japanese Web customers are using it to access sites in the States, because that's where all the sites are located. When one of them clicks on a button on an American Web page, a request is sent over the cable to the US. The request is infinitesimal, just a few bytes. The site in the States promptly responds by trying to send back a high-resolution, 24-bit color image of Cindy Crawford, or an MPEG film of a space shuttle mission. Millions of bytes. Your pipe gets jammed solid with incoming packets.
You're a businessperson. You want to make your customers happy. You want them to get their millions of bytes from the States in some reasonable amount of time. The only way to make this happen is to purchase more circuits on the cables linking Japan to the States. But if you do this, only half of each circuit is going to be used - the incoming half. The outgoing half will carry a miserable trickle of packets. Its bandwidth will be wasted. The correspondent agreement relationship, which has been the basis of the international telecom business ever since the first cables were laid, doesn't work anymore.
This, in combination with the havoc increasingly being wrought by callback services, is weird, bad, hairy news for the telecom monopolies. Mercogliano believes that the solution lies in some sort of bandwidth arbitrage scheme, but talking about that to an old-time telecrat is like describing derivative investments to an old codger who keeps his money under his mattress. "The club system is breaking down," Mercogliano says.
Somewhere between50° 54.20062' N, 1° 26.87229 W and50° 54.20675' N, 1° 26.95470 WCable Ship Monarch, Southampton, England
John Mercogliano, if this is conceivable, logs even more frequent-flier miles, to even more parts of the planet, than the cable layers we met on Lan Tao Island. He lives in London, his office is in Amsterdam, his territory is Europe, he works for a company headquartered in Bermuda that has many ties to the New York metropolitan area and that does business everywhere from Porthcurno to Miura. He is trim, young-looking, and vigorous, but even so the schedule occasionally takes its toll on him, and he feels the need to just get away from his job for a few days and think about something - anything - other than submarine cables. The last time this feeling came over him, he made inquiries with a tourist bureau in Ireland that referred him to a quiet, out-of-the-way place on the coast: a stately home that had been converted to a seaside inn, an ideal place for him to go to get his mind off his work. Mercogliano flew to Ireland and made his way overland to the place, checked into his room, and began ambling through the building. The first thing he saw was a display case containing samples of various types of 19th-century submarine cables. It turned out that the former owner of this mansion had been the captain of the Great Eastern, the first of the great deep-sea cable-laying ships.
The Great Eastern got that job because it was by a long chalk the largest ship on the planet at the time - so large that its utter uselessness had made it a laughingstock, the Spruce Goose of its day. The second generation of long-range submarine cables, designed to Lord Kelvin's specifications after the debacle of 1857, were thick and heavy. Splicing segments together in mid-ocean had turned out to be problematical, so there were good reasons for wanting to make the cable in one huge piece and simply laying the whole thing in one go.
It is easier to splice cables now and getting easier all the time. Coaxial cables of the last few decades took some 36 to 48 hours to splice, partly because it was necessary to mold a jacket around them. Modern cables can be spliced in more like 12 hours, depending on the number of fibers they contain. So modern cable ships needn't be quite as great as the Great Eastern.
Other than the tank that contains the cable, which is literally nothing more than a big round hole in the middle of the ship, a cable ship is different from other ships in two ways. One, it comes with a complement of bow and stern thrusters coupled to exquisitely sensitive navigation gear on the bridge, which give it unsurpassed precision-maneuvering and station-keeping powers. In the case of Monarch, a smaller cable repair ship that we visited in Southampton, England, there are at least two differential GPS receivers, one for the bow and one for the stern - hence the two readings given at the head of this section. Each one of them reads out to five decimal places, which implies a resolution of about 1 centimeter.
Second, a cable ship has two winches on board. But this does not do justice to them, as they are so enormous, so powerful, and yet so nimble that it would almost be more accurate to say that a cable ship is two floating winches. Nearly everything that a cable ship does reduces, eventually, to winching. Laying a cable is a matter of paying cable out of a winch, and repairing it, as already described, involves a much more complicated series of winch-related activities.
As Kelvin figured out the hard way, whenever you are reeling in a long line, you must first relieve all tension on it or else your reel will be crushed. The same problem is posed in reverse by the cable-laying process, where thousands of meters of cable, weighing many tons, may be stretched tight between the ship and the contact point on the seafloor, but the rest of the cable stored on board the ship must be coiled loosely in the tanks with no tension on them at all. In both cases, the cable must be perfectly slack on the ship end and very tight on the watery end of the winching machinery. Not surprisingly, then, the same machinery is used for both outgoing and incoming winch work.
At one end of the ship is a huge iron drum some 3 meters in diameter with a few turns of cable around it. As you can verify by wrapping a few turns of rope around a pipe and tugging, this is a very simple way to relieve tension on a line. It is not, however, very precise, and here, precise control is very important. That is provided by something called a linear engine, which consists of several pairs of tires mounted with a narrow gap between them (for you baseball fans, it is much like a pitching machine). The cable is threaded through this gap so that it is gripped on both sides by the tires. Monarch's linear engine contains 16 pairs of tires which, taken together, can provide up to 10 tons of holdback force. Augmented by the drums, which can be driven by power from the ship's main engines, the ultimate capacity of Monarch's cable engines is 30 tons.
The art of laying a submarine cable is the art of using all the special features of such a ship: the linear engines, the maneuvering thrusters, and the differential GPS equipment, to put the cable exactly where it is supposed to go. Though the survey team has examined a corridor many thousands of meters wide, the target corridor for the cable lay is 200 meters wide, and the masters of these ships take pride in not straying more than 10 meters from the charted route. This must be accomplished through the judicious manipulation of only a few variables: the ship's position and speed (which are controlled by the engines, thrusters, and rudder) andthe cable's tension and rate of payout (which are controlled by the cable engine).