Navigability

“ The Lead Line
SINCE the coming of the mariners’ compass many centuries ago, navigation has made steady headway. It is now an exact science, and vessels properly equipped with needed instruments and with men able to use them, can, no matter what the winds or seas, or how extended the voyage, be brought safely to their destination.
The instruments used in navigation are, the compass, by which ship’s courses are steered; the sextant by which observations of the sun, moon and stars are taken, and through which the latitude is ascertained ”

“ Driven by a stiff breeze, the ship noisily ploughs the seas with her keel as with a plough-share.
Life at sea.
On this ocean highway, along which one sees no trees, nor villages, nor towns, nor towers, nor steeples nor tombstones; on this road without posts or milestones, which has no boundaries save the waves, no relays save the winds, no lights save the stars, the finest adventure, when one is not travelling in search of unknown lands and seas, is the meeting of two vessels. They are mutually discovered on the horizon through the spy-glass; they turn each in the direction of the other. ”

“ But, you pattern of piety, the earthly navigator makes his plans, takes his measures, gives his orders, with a single eye to efficiency; there is nothing useless or purposeless on board; everything is to make navigation easy or possible; but as for the navigator for whom you claim the management of this vast ship, he and his crew show no reason or appropriateness in any of their arrangements; the forestays, as likely as not, are made fast to the stern, and both sheets to the bows; the anchor will be gold, the beak lead, decoration below the water-line, and unsightliness above. ”

“ To trace the origin of navigation, and to detail the numerous steps by which the merchant vessels of the great trading nations of the world have reached their present state of perfection; to record those discoveries in science and art connected with navigation, which enable the mariner to cross the ocean without fear and with unerring certainty; to dilate upon those triumphs of man’s genius and skill whereby he can bid defiance to the elements ”

“ The purposes of the marine of a country whose interests are so inseparably connected as ours are with the improvement of the art of navigation, would be very inadequately fulfilled, if our navigators were merely supplied with the means of determining by Nautical Astronomy the position of a ship at sea. ”

“ In practical navigation a vessel commences her voyage and [Pg 2] attempts to sail in a certain direction, but the well-known elements of compass error, variation and deviation, current, wind, seas and poor steering all divert the vessel from the projected course. In dead reckoning a navigator strives to keep track of his position by keeping a record of actual courses steered and distances run. ”

“ As my airship plowed ahead the wind fluttered my coat violently, as on the deck of an Atlantic liner, tho in all other respects it is more like river navigation with a steam-boat. It is not at all like sail navigation and all talk about “tacking” is meaningless. Imagine the air current to be a river running 10 miles per hour. If you go against the current, making 20 miles per hour, your net progress will be but 10 miles per hour. ”

“ He must furnish motive power not only, but he must direct her location, whether on the part or the starboard side, whether she shall be the inside boat or the outside one, when and how she shall be lashed to other boats, with what fastenings she shall be secured as she is dragged through the water, whether she shall go fast or slow, when, if at all, she shall drop astern, when she shall go to harbor, how long remain there, and what shall be her course of navigation. ”

“ Astronomy, geometry, and mechanics, which are in the first rank of science, are the materials which form the skilful pilot and the superior mariner. The theory of navigation is entirely derived from the two former, and all the machinery and movements of a ship are founded upon the latter. The action of the wind upon the sails, and the resistance of the water at the stem, naturally dictate an enquiry into the property of solids and fluids: and the state of the ship, floating on the water, seems to direct his application to the study of hydrostatics and the effects of gravity. ”

“ Taking advantage of the results of all exploring expeditions using new passages and all improvements in navigation; charts to be studied, the position of reefs and new lights and buoys to be corrected, for by the error of some calculator the vessel often splits upon a rock that should have reached a friendly pier; universal science to be kept pace with, studying the lives of all great discoverers and navigators, great adventurers and merchants, from Hanno and the Phœnicians down to our day; in fine, account of stock must be taken from time to time, to know how you stand. ”

“ The great point in practical navigation is to obtain a passage for a ship by removing or displacing the particles of water as quietly as possible, and to no further distance on either side than the greatest width of the vessel. ”

“ Thus it will be seen that in navigation there are currents in the sea and currents in the air to be considered, and that it requires a great deal of forethought, and knowledge, and experience, to take a ship in safety and with speed round the world. ”

“ It is the seamanship that will give him trouble; for to acquire that a long apprenticeship and considerable natural capacity are necessary.
For coasting purposes and for crossing narrow seas such as the Channel, and the North Sea, and even for a voyage to the Baltic, sextants, chronometers, and other instruments of navigation proper are not required, and the following is a complete list of all that is needed for the purpose of finding one’s way. 1. The necessary charts. 2. A mariner’s compass. 3. A parallel rule. 4. A pair of compasses or dividers. 5. A log ship and line. ”

“ It has long been our chief reliance for rapid traveling. You find us in this ship; but, although navigation is a perfected science, this mode of traveling is tedious, and ships are used only for pleasure and such out-of-the-way trips as this. Journeys from place to place over established routes are made in large tubes, in which the cars are propelled by electricity. These tubes run both on land and water, being suspended in the latter a little way below the surface. Both tubes and cars are air-tight, and the adjustment is so perfect that the cars slide along with the greatest ease. ”

“ Where vessels approaching are yet so distant from each other, or where the lines of approach, though parallel, are so far apart as not to involve risk of collision, that rule of navigation has no application to the case. ”

“ He then compares that position with his voyage plan, his operational commitments, and his predetermined “dead reckoning” position. A good navigator anticipates dangerous situations well before they arise, and always stays “ahead of the vessel.” He is ready for navigational emergencies at any time. He is increasingly a manager of a variety of resources--electronic, mechanical, and human. Navigation methods and techniques vary with the type of vessel, the conditions, and the navigator’s experience. ”

“ The science of navigation is considered very dignified by them, and they possess rafts and triremes, which go over the waters without rowers or the force of the wind, but by a marvellous contrivance. And other vessels they have which are moved by the winds. They have a correct knowledge of the stars, and of the ebb and flow of the tide. They navigate for the sake of becoming acquainted with nations and different countries and things. ”

“ Knowledge of the kind, in river navigation, is peculiarly essential, as the current frequently shifts from one side towards the other, and the track of navigation is often obstructed by snags, sand-bars, and shoals, which no degree of skill would enable the mariner or pilot to avoid without a prior knowledge of their existence. ”

“ Thus the effect of currents and wave motion, and the maintenance of trim and equilibrium are not factors in the successful navigation of the vessel; in fact, navigation becomes surer on the surface, as one is travelling in a medium which does not constantly change like the surface water from the effects of winds, waves, and currents. When the divers desire to leave the vessel they go into the diver’s compartment, located in the forward portion of the ship, and close the door communicating with the living quarters. ”

“ Coming up with the vessel, or she and you drawing near in passing, reading the numbers by the spyglass, and arranging all the signals, is an agreeable occupation for the larger part of two hours, including the departure of the vessels from each other, as though friends were parting, leaving the ocean more a solitude than before.
Meeting vessels, or passing them at a distance, exchanging signals, making out their numbers, bring remote parts of the earth suddenly to mind. Thus new trains of thought succeed each other entirely disconnected. ”

“ Accordingly he said: "Art can construct instruments of navigation such that the largest vessels, governed by a single man, will traverse rivers and seas more rapidly than if they were filled with oarsmen. ”

“ This extensive inland navigation, open as I have stated it to be, can only be considered traversable to the boats of the country, which are flat bottomed, and do not draw more than four feet of water, when heavily laden. The largest of these carry about seventy-five tons English: science and capital might improve the build of these vessels; but in extending our commerce, or in setting on foot a flotilla, the present model would ever be found most convenient. Vessels of a sharp build are liable to upset when they run aground on the sand-banks. ”

“ Here, however, the facilities for observation of a sea-faring life have been directed towards an object of inquiry, which must prove of immense utility in navigation and commerce. And, perhaps, even landsmen may not find it uninteresting, that even that proverbially fickle element, air, obeys certain fixed laws, a more accurate acquaintance with which must be of the utmost importance to the denizen of terra firma, as well as187 those "that go down to the sea in ships, that do business in great waters." ”

“ The navigation part is, no doubt, very easy, even the extra master's examination presenting no serious difficulty to a well-educated lad. That part may be learned—often is learned—without the learner possessing any knowledge of the sea at all. But the other, especially for master, with its searching questions into maritime legal matters, knowledge of the coasts added on to the intricacies of ship-handling under all circumstances of peril, is, I should say, perfect for its purpose, and such as no mere theorist can hope to pass. ”

“ Gryde proceeded. “The ship is steering by the chart, as these people think, a degree or so to the south of the reef. As you know perfectly well, we are steering right on to it. When you feel the first shock, you will know exactly what to do. That water balance must be shifted as arranged to convey the idea that the vessel is filling, and thus increase the confusion. This course will also lighten the ship by the head, and enable her to float.” ”

“ The Art And Science Of Navigation Marine navigation blends both science and art. A good navigator constantly thinks strategically, operationally, and tactically. He plans each voyage carefully. As it proceeds, he gathers navigational information from a variety of sources, evaluates this information, and determines his ship’s position. ”

“ The next object is to apply what has been advanced to the theory of aërial navigation; and the following description will convey a just idea of the best method of effecting it. Suppose a sail to be made of thin cloth, of a firm texture, containing two hundred square feet; and that the weight of the man and the apparatus is 200 pounds. Then if the wind blow with a velocity of 35 feet per second, in a certain direction, at the same time that a cord in that direction sustains a tension of 21 lbs. from being fixed to the machine, the whole apparatus will be suspended in the air. ”

“ I calculated upon the sea being navigable for six weeks to come, and probably more, if the state of the ice would permit us to edge away to the southward in our progress westerly: our prospects, indeed, were truly exhilarating; the ships had suffered no injury; we had plenty of provisions; crews in high health and spirits; a sea, if not open, at least navigable; and a zealous and unanimous determination, in both officers and men, to accomplish, by all possible means, the grand object on which we had the happiness to be employed. ”

“ But beneath a tunnel so strange as it may seem,
And cars by the hundreds pass thru it ev’ry day,
Bearing a large commerce upon its destined way.
Far greater the traffic that daily passes thru,
In the thousands of ships that sail thy waters blue,
Sailing ships and steamships, and boats of ev’ry form,
Fit to sail a river, or face an ocean storm.{132}
How wonderful the change since five score years ago,
From the Indian canoe that was so small and slow,
To the mammoth steel ships of immense size and weight,
Large enough to carry eight thousand tons of freight. ”

“ The use of sea cardes for navigating during long voyages he regards as very necessary for three reasons: they show you (1) how one place bears from another; (2) the distances between the places; (3) in what latitude any place is. But the master or pilot of the ship is also to bear in mind the effect of tides, currents, the surging of the sea or scantiness of the wind, which might put the ship to leeward of her course. ”