Atlantic High
Page 16
And then, one day you will present identical figures to two machines—only to get different results.
I note the log for June 10, with my lapidary exasperation written out on the left-hand page in capitals.
DATA: GMT 18-23-28
HO 51-06
TABLES: Zn 263°, 31 Towards
PLATH: Zn 263°, 68 Towards
H/P: Zn 263°, 31.5 Towards
I find a notation: “The Plath is inconsistent with previous sun sight (at 11:22). Question: was that sight done on Plath? If we saved data, we could check with H/P. Tell Danny.” And, still fretting about it an hour later:
“1330 FLASH! Trouble with the Plath. It is giving false and irregular conclusions. Its GMT is correct. [I should have noted that its chronometer was correctly set.] Not to be used until further notice.”
The next day I ran it through a series of tests—and it worked perfectly.
I suppose, then, that one can conclude only that a) the experts also make mistakes, and do so in the coolness of their air-conditioned offices, surrounded by professional copy editors; so that navigators at sea, a fortiori, are going to make mistakes, though some of them make more mistakes than others.
And then there are glitches which no layman can hope to anticipate. In describing difficulties with the HP-65 in my last book I provoked a number of correspondents who proffered possible explanations. Only a month ago I received one wholly arresting and satisfying commentary on the endeavor, to account for the anomalies I had plotted.
“In Step I,” writes Mr. John F. Hartray, Jr., an architect in Chicago, “the calculator rounds off the date, 19 June 1975, to the nearest hundredth of a year, 75.47 or 47% through 1975. This is too crude an approximation for your purpose. In a hundredth of a year 3.65 days pass, during each of which the earth must rotate about one degree beyond a full circle to compensate for its orbital motion (see enclosed sketch). This results in an increase in the Greenwich Hour Angle (GHA) of Aries of about 3.6 degrees. Step 2 converts the program from solar to stellar or sidereal time (366 days per year). This transfers the high rate of change in GHA from the fixed stars to the sun which is undoubtedly why it takes two chips of almanac data [Mr. Hartray was referring to the obsolete HP-65] to load the sun into the program while stars require only one chip. The 3.65 day rounding-off probably had little effect on star calculations. The only variation which must be accounted for grows out of the change in the earth’s orbital velocity at various points on its elliptical path (faster when closer to the sun). This doesn’t change much in 3.66 sidereal days. On sun sights, however, the rounding off can result in an error of up to plus or minus 108 nautical miles (3.6 degrees x 60 miles divided by 2) for sights taken east or west at the equator. This error decreases as: a) the time on which you take your sight approaches the center of the 3.65-day period, b) the azimuth of the sun at the time of the sight approaches north or south, c) your position moves away from the equator.
“Perhaps,” the author meditatively concludes, “the program writer felt that enough of these conditions would usually apply to enable him to escape detection. Besides, if the calculation doesn’t work out, most yachtsmen would be more likely to place the blame on their sextant, eyes, or arithmetic rather than on such an expensive new gadget. Actually it shouldn’t be too difficult for Hewlett-Packard to develop a program for solar navigation based on the initial rounded-off date which remains on solar time and uses the same GHA data that appears in the printed almanac. Within the solar time frame, the relative movements of the sun are negligible over a 3.65-day period.”
Sounds plausible to me, though there was a faintly huffy putdown by Ken Newcomer. He would—given the advances in the navigational programs—in any event consider the question posed as of purely antiquarian interest. The point is nevertheless etched in concrete: the experts slip up. Their machines, though marvelous, bear watching. Don’t—ever—forget how to use the tables.
For all that you are constantly reading about navigators bringing down the stars at night, what you most generally get, on small sailing boats, is navigators trying to bring down stars at night. The conditions are simply not propitious. David, the first mate, had taken a job during the preceding winter that required him to spend much of the night out on deck in a cargo vessel that slowly, ever so slowly, traversed the Pacific. Being of active mind, David decided there and then to master star identification, which he did; which I have never done, consulting instead on every occasion the star-finder and groping my way through individual star recognition, rather than star recognition by constellation, which is how the experts do it.
In any event, faced now, traveling from Bermuda to the Azores, with a two-thousand-mile eastern passage, I could know that pretty much the same stars and planets would make an early appearance off the starboard bow at dusk. In shooting your stars, you should begin with the easternmost stars, because they are the first to become visible, the residual light from the sun setting in the west giving you too bright a horizon to bring down the western stars until the sun is well down—by which time the eastern horizon may be too amorphous.
So: decide which stars you are going to shoot, and keep the list short—not more than four became my rule. These you can select by reference to their location and intensity on the star-finder, or by consulting the tables in HO 249 (one of three generally used systems) which gives you “selected stars” for every situation (measured by the Greenwich Hour Angle of Aries at the time you propose to shoot).
Now the textbooks teach you to locate the star, and to approximate the anticipated angle on your sextant. Let us say that you are looking for Arcturus and you know that at 7 P.M. it is scheduled to show up at 42 degrees and 15 minutes at an azimuth of 210 degrees. You note that where you are there is a variation of 16 degrees west longitude, so you turn 226 degrees by the compass with your sextant pre-set at 42 degrees 15 minutes. You spot a star that may very well be Arcturus. You are using a fine sextant, let us say a Plath or a Tamaya, both with telescopic lenses, powered at about 4 ? 1, so that when you find Arcturus it is much brighter than it would be if you were merely making it out with the naked eye.
You begin, then, to adjust the vernier scale to fine-tune the star on the horizon. What regularly happens is that you will either a) lose the star; or b) lose the horizon. If the latter, it is because the horizon has become too indefinite and you cannot with any sense of assurance conclude what is horizon, and what is sky. If the former, it is because you have been so pitched about by the movement of the boat that what you had carefully trained on as Arcturus turns out now to be another star nearby.
Remember, with the telescopic apparatus, even as the star is magnified four times, so the field of vision through the sextant eye is reduced by a factor of four. This means that, thanks to the telescope, you have one-sixteenth as large an area of the sky to look at. To hang on to a star when the deck is pitching requires something on the order of an in-built gyroscope. In a way, that exactly is what our complicated musculature provides us, else it would be impossible to take even a midday sun sight in a sea, let alone walk across Niagara Falls on a tightrope. But the difficulty at night advances geometrically as the tiny star surrounds itself with other tiny stars, leaving you uncertain as to identification; and meanwhile the horizon is becoming progressively elusive, very soon achieving indistinguishability.
Most celestial navigators know the old trick of turning the sextant upside down when they have trouble aiming at the desired celestial body. The idea is to sight, say, Arcturus by looking straight at it through the eyepiece. The arc of your sextant is then, roughly speaking, concentric to the curvature of the earth, rather than the opposite. You need therefore to keep your eye on Arcturus and, with your right hand, work the sextant knob and vernier to lift the horizon up to Arcturus, rather than do the conventional thing of bringing Arcturus down to the horizon.
Now, old salts will not be surprised if you start out that way—if you are having trouble finding Arcturus. Bring the horizon,
they’ll tell you, to where it is close to Arcturus. Then resume the normal sextant position, both ends of the arc curving once again heavenward: now do your fine tuning.
I say nuts. Do your fine tuning with your sextant inverted.
As I advanced on these insights, I left my Rolls-Royce Tamaya in its case and brought out my little fifty-dollar emergency sextant (I cannot give its brand name because I never remarked it, and it was stolen on the way back from Spain). I could divest it, with a twist of my fingers, of its little telescope, and aim through the naked eyepiece. I inverted the sextant, on the night of June 12. For the first time in my life I achieved an absolutely perfect little triangle, bringing down, or rather taking the horizon up to, Spica, Vega, and Arcturus. And here is an important dividend. Since you are pointing now at Arcturus, having brought the horizon up to it, you have substantially eliminated what one might call the pendulum factor. When you bring a star down to the sea, you cannot know that it sits truly on top of the sea unless you simulate with your sextant the movement of a pendulum, to establish that you are holding it perfectly perpendicular. If your hands are slanted, you will find, when you arc the sextant, that you are sinking the star into the ocean or floating it up into the sky.
But when you lift the horizon, you all but eliminate the pendulum. If the horizon is now tangential to the heavenly body, it makes little difference if the sextant is at an angle—the distance measured doesn’t change. You can swing your sextant fifteen degrees clockwise or fifteen degrees counterclockwise, and if Arcturus was touching the horizon in the first instance, it will be touching the horizon in the second.
To eliminate the pendulum factor is a huge blessing particularly in heavy weather. The sensation is really breathtaking. There it was, my fix. Moreover, it revealed a considerable southerly drift since taking the noon sight, and so I altered the course instantly. Every night thereafter I succeeded in getting three stars, or at least two, and one planet. With the Navicomp, as noted, even the inconvenience of plotting is eliminated—by asking the machine for a fix based on the two most recent sights. I am, as I write, experimenting with a Plath model sextant that comes without magnification. I have not repeated my successes of the summer, but on the two occasions I tried misty clouds stood between me and the stars I had my beady eyes on. But I shall have them, I warrant; and so will you, if you do exactly as I say—always a good idea.
11
Van, having for the second time in our joint experiences traversing the Atlantic Ocean accepted the commission of meteorologist, undertook—as is his way—to make some systematic inquiries. He was very penitent, after the first trip, about his failure to apprise himself of the radio frequencies through which vital weather data are given relevant to the particular region in which you are traveling. The same day we landed in Marbella in 1975, a trim and seaworthy yacht sailing from Bermuda to Newport capsized. We read deeply in the matter, and it transpired that just a little essential information would have given the boat’s skipper (he and his crew were all rescued by a Russian freighter) time to anticipate the movements of the oncoming hurricane, by rushing back to the sanctuary of Bermuda.
Blame #1): Bermuda Radio was an unconscionable one-day late in relaying information issued by the National Hurricane Center in Miami (telephone 305-666-0413). Blame #2): The skipper, proceeding insouciantly, under the dispensation of the Bermuda weather report, sallied on down the rhumb line ignoring savage empirical data until it was simply too late. Blame #3) : Observing that things were obviously getting worse than anything anticipated by Bermuda Radio, the skipper should have more ingeniously improvised a strategic retreat from the firestorm.
All this Van knew; and, to be sure, he proceeded on my assurance that we would have a functioning Weathermax on board. To find oneself without such an instrument, if you began by assuming its presence, is a little like being dispatched as navigator on the assumption of a functioning chronometer on board, only to find that it doesn’t work. If you have no chronometer, you are sorely handicapped; but Columbus made significant headway without one, as did Cortés, Magellan, Drake. If you don’t have the Weathermax, you assume that you will get, from the radio, essentially the same information it yields, only by different, more complicated means.
I have a more or less permanent impression of Van crouched over the most imposing radio on board. To speak of the most imposing radio on board the Sealestial is on the order of speaking of the most imposing automobile in the Paris Automobile Show. It was a Panasonic Kandy-Kolored Tangerine Supermax this or that. It is not an exaggeration to say that—counting this Mickey Mouse—there were maybe twenty radios on board, if you count Dick’s ten. But the Panasonic was the dreamboat, with digital readouts, the whole business. Probably Van spent a cumulative twenty-five hours trying to get it to perform. He had tables giving information about where, and when, and at what frequency, reports would be broadcast giving a vessel an idea of what lay ahead of it on the plotted course.
The easy way to say it is that the Panasonic didn’t work. That much is certainly true. And, of course, it relied ultimately on the same aerial on which our delinquent radiotelephone relied. On board the Sealestial there were considerable resources of electronic and engineering talent. If you throw into the pot everything Allen knows, everything Reggie knows, add David, plus a mite from Van, Dick, and from me an unpredictable but occasional capacity to descry from a written instruction an actual meaning, you had quite a lot.
Not enough. Primary blame, one supposes—not having conducted an inquest—falls on technology: the signals simply didn’t come in at the predesignated moments at the predesignated channels. But having said as much, it is necessary to communicate the full meed of the amateur sailor’s frustration at the forbidding bureaucratization of the language of the sea.
Hugh Kenner had on several occasions made an interesting point on the subject. He had made it directly to me, and indirectly to Hewlett-Packard’s Ken Newcomer: namely, that it; really does make sense, when writing instructions for the use of people at sea, to recognize that some of them are in small boats, and then to imagine conditions at sea for such folk. After all, the QE2, if really confused about the weather directly ahead, can always wire the Privy Council or whoever and get satisfaction. Aboard such vessels as the Sealestial, typically the circumstances are less auspicious. It is very black outside, the winds increasing in velocity. We have just taken a reef in the mainsail, checked out the barometer but found no significant movement. One watch member is at the wheel, the second approaches the radio, having first consulted Van’s radio log. He stares, to see what is available at this moment, in order to get an idea of what lies ahead.
I did this one night and I quote verbatim what the Admiralty List of Radio Signals, 1972, shot back at me:
“This volume should be corrected each week”—those of us who confess our sins less frequently than once a week marvel at the suggestion that every single Friday, on the way from the office to the country, one should check with the Admiralty List of Radio Signals, 1972. You turn to the relevant page, page 149 in our case, where is advertised, “Transmission from St-Lys, Special Marine Weather Bulletins and Storm Warnings. TIME: (messages in French); 30 m. past two successive EVEN hours, immediately before the traffic lists. If necessary, a repetition is made at the first EVEN hour in which the watch keeping schedules of single-operated ships in Zone A. (8.510: ‘Not on Sundays or holidays.’)” There are those for whom the above is translatable into English, but they are rare; and the probability is high that they maintain their special cerebral sensitivities by insulating themselves from tumultuous situations at sea, with a fractious radio in their hands, salt water whistling past their ears, minor and major objects crashing about them and, over it all, the sound of radio static.
Moral? Teddy Tucker’s is simple. What he says is characteristically fatalistic: Go where you want to go, and take your chances on the weather. Teddy is very tough, and very lucky, and very ingenious. My own position is down the middle.
Forget trying to tease out of the weather the kind of information that might prove critical to a racing sailor. Take, in a cruise, what comes—but try to make certain that you and a man-eating hurricane are not headed on converging courses. And this means that you need either a Weathermax (luxury stuff) or a reliable radio with one or two frequencies that will actually talk English to you, and tell you what you need to know. You are, in my experience, better off tuning in constantly to one or two very good stations stateside until about Longitude 55°, then go to England and count on them to tell you if something ominous is coming up. If so, and your radio works (try to see to it that it does), then call the Hurricane Center and keep track of the storm or hurricane, and make entries, every hour, of your barometer reading.
Having said as much I confess that if I were tomorrow to set out on the identical journey I would not know offhand which frequencies to recommend. What I would do, the third time out if ever I should go again, is talk to one or two captains of the regular freighter runs. Ask them. The kind of thing they tell you—what frequency to keep your radio tuned to—isn’t likely to show up in the yachting magazines. Or in the books of dilettantes.
It’s possible to get cross, every now and then, with Bermudians, but safe to generalize that they are really the friendliest people in the world. Their anxiety to be helpful seems to rub off on anyone who spends time there, as witness the wonderful amiability of the people at the U.S. Naval Base, to the operations center of which Van directed our taxi when we were on our way to St. George’s to board the Sealestial. He desired from the meteorological officer projections of the weather, and from an obliging young man we got Xerox copies of four sheets predicting the area isobars four days down the line, a high-pressure escort, beginning that very day, in the direction we were traveling. These bits of paper are by no means easy for the amateur to read: I have a terrible time with them, and devote as much attention to the expression on Van’s face as to the efforts to transcribe what the stigmata are trying to say to me. The rule of thumb, we all know, is High Pressure is Good, and Low Pressure is Bad. But the rule of thumb is qualified by what it is that the sailor is in search of—namely, wind. Not too much wind, mind, but wind enough to sail by. So that—particularly if you were racing—you would avoid heading directly into the center of a high, lest you find yourself windless. You