Chapter 5

THE NATURAL LAWS OF RESISTANCE, POWER, AND SPEED, WITH TABLE: THE RESISTANCE VARIES AS IS THE SQUARE OF THE VELOCITY: THE POWER, OR FUEL, VARIES AS THE CUBE OF THE VELOCITY: THE RATIONALE: AUTHORITIES CITED IN PROOF OF THE LAW: EXAMPLES, AND THE FORMULAE: COAL-TABLE; NO. I.: QUANTITY OF FUEL FOR DIFFERENT SPEEDS AND DISPLACEMENTS: DEDUCTIONS FROM THE TABLE: RATES AT WHICH INCREASED SPEED INCREASES THE CONSUMPTION OF FUEL: CONSUMPTION FOR VESSELS OF 2,500, 3,000, AND 6,000 TONS DISPLACEMENT: COAL-TABLE; NO. II.: FREIGHT-TABLE; NO. III.: AS SPEED AND POWER INCREASE FREIGHT AND PASSENGER ROOM DECREASE: FREIGHT AND FARE REDUCED: SPEED OF VARIOUS LINES: FREIGHT-COST: COAL AND CARGO; NO. IV.: MR. ATHERTON'S VIEWS OF FREIGHT TRANSPORT.

The foregoing arguments bring us to the conclusion that steam, however desirable, can not be profitably employed in commerce generally as an agent of transport; and that it is best applicable to the rapid conveyance of the mails, passengers, specie, and costly freights only. That this fact may be presented in a clearer light, and that we may see the almost incredibly high cost of rapid steaming, or the attainment of a speed sufficiently high for the carriage of important mails, it will be necessary to make some critical inquiries concerning the working cost of steam power, under any conditions, as applied to marine propulsion. Much misapprehension prevails on this point among nearly all classes of the people, and even among the rulers of the country whose action controls the destiny and uses of this valuable power. It is hardly to be expected, however, that gentlemen engaged actively in the all-engrossing pursuits of business or of public life, with a thousand different sets of ideas to be matured on a thousand different subjects, such as demand the attention of Congress, and the Departments of the Executive Government, should be practically or even theoretically acquainted with a profession which requires years of close application and study, and a wide field of practical, daily observation and experience. It would be as absurd for unprofessional gentlemen of any class, as well from the walks of statesmanship and the Government as from those of quiet private life, to assume an acquaintance with the theory and practice of navigation, and the cost, embarrassments, and difficulties attending steamship enterprise, as it would for any two or three of them to enter an ocean steamer for the first time of their lives, and essay to work the engines and navigate the ship across the seas. The skill and knowledge requisite for such a task would require years of application; and it can not be reasonably supposed that those entirely unacquainted with the theory and parts of an engine, should know much about its capabilities, or the cost attending its use.

But there are approximate conclusions, readily applicable to practice, at which even the unprofessional can arrive with certainty and security on a proper presentation of the prominent facts and theories concerned; and that these may be given to the public in a reliable and intelligible form, for the removal of the doubts and obscurities which have hung around the subject, is the chief object of this publication. This inquiry becomes the more important as the speed of American steamers is proverbially beyond that of any other steam vessels in the world. From the first conception of fluvial and marine steam propulsion by Fitch and Fulton, the public and the inventors themselves regarded the new application of this power with the more favor as it promised to be a means of shortening the long distances between the different parts of our own large country. And the same object has acted as a stimulus ever since to that increase of speed which has placed localities all over this country, hitherto days apart, now, probably, but as many hours. The slow trip through marshes and rivers, over hills and mountains, and by the meandering roads of the country, between New-York and Albany, once required from four to six days; but the attainment of twenty-five miles per hour in our fast river steamers has at length placed that capital within six hours of the Metropolis. And, as in this instance, so has the effort been throughout our whole country, and upon the ocean, until we have attained, both upon the rivers and the high seas, the highest speed yet known, notwithstanding the important fact that steamship building is a new and not fully developed species of enterprise in this country. We have already seen how imperatively the spirit of the age and the genius of our people demand rapid steam mails by both land and sea, and a rapid conveyance of passengers; and it would be unreasonable to suppose that if we required these for the development of our youth, they would be less necessary for the fruitful uses of manhood and maturity. It is abundantly evident that the American people are by nature and habit a progressive and unusually hurrying people; and it is not to be supposed that they will reverse this constitutional law of their nature in their attempts at ocean navigation.

To answer the question, "What is the cost of high, adequate mail speed?" requires something more than an inquiry into the quantity of fuel consumed; although this is the principal element of its cost. We must consider that the attainment and maintenance of high speed depend upon the exertion of a high power; and that,

I. High speed and power require stronger parts in every thing: in the ship's build, the machinery, the boilers, and all of the working arrangements:

II. High speed and power require a larger outlay in prime cost, in material and building, for the adequate resistance required by such power:

III. High speed and power require more frequent and costly repairs:

IV. High speed and power require more watchfulness, a more prompt action, and consequently more persons:

V. High speed and power require more fuel, more engineers, more firemen, and more coal-stokers.

1. These propositions are nearly all self-evident to every class of mind. That a high speed attained through the exertion of a high power will require stronger parts in every thing that exerts a force or resists one, is as manifest as that a force necessary to remove one ton of weight will have to be doubled to remove two tons. In the prime construction of the hull this is as requisite as in any other part. The resistance to a vessel, or the concussion against the water, at a low rate of speed, will not be very sensibly felt; but if that speed is considerably increased and the concussion made quicker without a corresponding increase in the strength of the frame and hull of the ship generally, we shall find the ship creaking, straining, and yielding to the pressure, until finally it works itself to pieces, and also disconcerts the engines, whose stability, bracing, and keeping proper place and working order depend first and essentially on the permanence and stability of the hull. If the resistance to a vessel in passing through the water increases as the square of the velocity, and if in addition to this outward thrust against the vessel it has to support the greater engine power within it, which has increased as the cube of the velocity, then the strength of the vessel must be adequate to resist without injury these two combined forces against which it has to contend.

The same increased strength is necessary also in the engines and boilers. It is admitted by the ablest engineers, and verified by practice, as will be shown in another part of this Section, that to increase the speed of a steamer from eight to ten knots per hour, it is necessary to double the power, and so on in the ratio of the cubes of the velocity. Suppose that we wish to gain these two knots advance on eight. It is evident that, if the boilers have to generate, and the engines to use twice the power, and exert twice the force, they must have also twice the strength. The boiler must be twice as strong and heavy; the various working parts of the engine must be twice as strong: the shafts, the cranks, the piston and other rods, the beams, the cylinders, the frame work, whether of wood or iron, and even the iron wheels themselves, with every thing in any way employed to use the power, overcome the resistance, and gain the speed. There is no working arrangement in any way connected with the propulsion of the ship that does not partake of this increase; every pump, every valve, every bolt connected directly or indirectly with the engine economy of the ship.

2. In the second place, seeing that much greater strength of parts is required to overcome the increased resistance, it is equally evident that this high speed and power thus require a larger outlay in every point of the prime construction of the vessel and engines by which the speed is to be attained. The hull's heavier timbers cost a higher price according to size than the direct proportion of size indicates. Large and choice timbers are difficult to get, and costly. The hull must also be strengthened to a large extra extent by heavy iron strapping and bracing, which, unlike the rest, cost in the ratio of the material used. So with the engines. The shaft, which weighs twice as much, does not cost only twice as much, but frequently three or four or five times as much. This arises not from the weight of the metal, as is evident; but from the difficulty of forging pieces that are so large. The persons engaged in the forging and finishing of the immense shafts, cranks, pistons, etc., used in our first class steamers, frequently consider that the last and largest piece is the _chef d'oeuvre_ of the art, and that it will never be transcended, even if equalled again. They have expended all of their skill and ingenuity in the task, and have not succeeded sometimes until they have forged two or three new pieces. When a great work of this kind is done, it may be discovered in the turning, polishing, and fitting up, that it has at last a flaw, and that it will not do for the service intended. As a matter of course, it must be thrown aside and a new piece forged. This was but recently the case with one of the shafts of the "Leviathan," in England. So with the shafts of the new Collins' steamer "Adriatic." They were forged in Reading, Pennsylvania, and in addition to their enormous prime cost had to incur that of shipment from the interior of Pennsylvania to the city of New-York. In all such cases the prime cost increases immensely, and to an extent that would hardly be credited by those not practically familiar with the subject.

3. Again, high or increased power and speed require more frequent and more costly repairs. Friction arises from the pressure of two bodies moving in opposite directions, and pressure results from the exertion of power, and in the ratio of the power applied. The amount of friction, therefore, is in the ratio of the power expended and of the extra weight of parts required for that power. But the effects of friction require a higher ratio when the power is greatly multiplied, as in the case of high speed. An immensely heavy shaft exerting an unusual force is certain to greatly heat the journals and boxes, and thus wear them away far more rapidly. Also a rapid motion of heavy parts of machinery, and the necessarily severe concussions and jarrings can not fail destroying costly working parts in the engine, and necessitating heavy and expensive repairs and substitutions. An ordinary engine working at a slow and easy rate, will not require one tenth the repairs necessary if it were working up to a high power and accomplishing a high speed. With any little derangement the engines can stop and the injury can be repaired before it reaches any magnitude. But with rapid mail packets the engines must run on, and the derangement which at first is small, will amount in the end, when the voyage is completed and the mails are delivered, to a sum probably ten or twenty times as great as in the case of the vessel that stops and makes her repairs as she requires them. The exertion of a high mail power causes many costly parts to burn out from unrelieved pressure and friction, which would not be the case under other conditions. It is also nearly impossible for the best built engines in the world to make fast time without breaking some important part at every trip or two, or so cracking and injuring it from the continued strain, that a wise precaution requires its removal to make the steamer perfectly sea-worthy. Every practical man knows these difficulties, and every steamship owner estimates their importance according to the immense bills they occasion month by month, or the delays and losses which they cause unless he has expended large amounts of capital in providing other ships to take their place on such occasions of derangement.

Nor is the burning out of heavy brass, and composition, and steel pieces, or the breaking of large and troublesome parts in the engine the only source of repairs on a steamship. The boiler department is particularly fruitful in large bills of repairs, especially if it be necessary to attain a good mail speed. It stands to reason that if the whole ship can not be filled with boiler power, which with reasonably high fires, would give enough steam, then the boilers which are used must be exerted to their highest capacity, or the rapid speed can not be attained. Many suppose that the boilers may generate twice the quantity of steam without any appreciable difference in the wear and tear; but this is a decided error. For high speed, and what I mean by high speed is simply that which gives a sufficiently rapid transit to the mails, the fires must be nurtured up to their highest intensity and every pound of coal must be burned in every corner of the furnaces which will generate even an ounce of steam. This continued heat becomes too powerful for the furnaces and the boilers, and they begin to oxidize, and burn, and melt away, as would never be the case under ordinary heat. When the ship comes into port it is found that her furnaces must be "overhauled," her grate bars renewed, her braces restored, her boilers patched, sometimes all over, several of their plates taken out, thousands of rivets removed and supplied, and probably dozens of tubes also removed and replaced with new ones. But this is not all. The best boilers can not long run in this way. After six to seven years at the utmost, they must be removed from the ship altogether, and new ones must be put into their place. This is also a most expensive operation. The boilers constitute a large share of the cost of the engine power. To put a new set of boilers in one of the Collins steamers will cost about one hundred and ten thousand dollars, and this must be done every six years. The boilers of the West-India Royal Mail Steamers, which run very slowly, last on an average, six years.[A]

[A] Statement by Mr. Pitcher, builder, before the Committee of the House of Commons. Murray on the _Steam Engine_, p. 170, Second Edition.

But this is not all. To restore the boilers, a ship has to be torn literally almost to pieces. All of the decks in that part must be removed and lost; the frame of the ship cut to pieces; large and costly timbers removed, and altogether an expense incurred that is frightful even to the largest companies. To insure perfect safety and to gratify the wish of the public, this is generally done long before it is strictly necessary, and when the boilers are in a perfectly good condition for the working purposes of ordinary speed. But precaution and safety are among the prerequisites of the public service, and must be attained at whatever cost. On slow auxiliary freighting steamers this would be by no means necessary. But the extent and cost of these repairs on steamers far exceed any thing that would be imagined. They are supposed to be twelve per cent. per annum of the prime cost of a vessel of ordinary speed, taking the whole ship's life together at twelve years at the utmost. Atherton in his "Marine Engine Construction and Classification," page 32, says of the repairs of steam vessels doing ordinary service in Great Britain, where all such work is done much cheaper than in this country: "By the Parliamentary evidence of the highest authorities on this point, it appears to have been conclusively established, that the cost of upholding steamship machinery has of late years amounted, on the average, to about L6 per horse power per annum, being about 12 per cent. per annum, on the prime cost of the machinery, which annual outlay is but one of the grand points of current expense in which steamship proprietors are concerned." Now, if these were the repairs of the slow West-India Royal mail steamers, which ran but 200 days in the year, and that at a very moderate speed, and in the machine shops of England, where at that time (previous to 1852) wages were very low, they can not be less in this country, on rapid mail steamers, where wages and materials are very high, and where marine engineering was then in its infancy.

There are some facts on this subject which prove the positions here taken. The Collins steamers have been running but six years, and yet their repairs have amounted in all to more than the prime cost of the ships, or to about eighteen per cent. per annum. They were as well and as strongly built originally as any ships in the world, as appears from the report which Commodore M. C. Perry made to the Department regarding them, and from the fine condition of their hulls at the present time. Their depreciation with all of these repairs has not been probably above six per cent. per annum. They will, however, probably depreciate ten per cent. during the next six years, and at the age of twelve or fourteen years be unfit for service. The steamers Washington and Hermann, which had strong hulls, have been run eight years, and are now nearly worthless. Their depreciation has been at least ten per cent. The steamers Georgia and Ohio, which Commodore Perry and other superintending navy agents pronounced to be well-built and powerful steamers, (_See Report Sec. Navy_, 1852,) ran only five years, and were laid aside, and said to be worthless. With all of the repairs put upon these ships, which were admitted to be capable of doing first class war service, as intended, they depreciated probably seventeen per cent.; as it is hardly possible that their old iron would sell for more than fifteen per cent. of their prime cost. These steamers paid much smaller repair bills than the Collins, and were not so well constructed, or at so high a cost. American steamers do not, upon the average, last above ten years; but if they reach twelve or fourteen, they will pay a sum nearly equal to twice their cost, for repairs and substitutions. Nor is this all. The life of a steamer ends when her adaptation to profitable service ceases. She may not be rotten, but may be so slow, or of so antiquated construction, or may burn so much more fuel than more modern competitors, that she can not stand the test of competition.

4. We thus see that not only are the requisite repairs most extensive and costly, but of such magnitude as to greatly reduce the earnings of any class of steam vessels. But this is not the last costly consequence of mail speed. It requires more cautious watchfulness of the engines, the boilers, the deck, and of every possible department of the navigation, even including pilotage. It requires also more promptness and dispatch in every movement, and hence a much larger aggregate number of men. More men are necessary to keep up high fires; twice as many men are necessary to pass twice as much coal; twice as many engineers as under other circumstances are necessary for the faithful working of the engines, and any accidents and repairs which are indispensable on the ocean; and a larger number of sailors and officers is necessary to all of the prompt movements required of the mail steamer. The Havre mail steamers, the "Arago" and "Fulton," never carry less than six engineers each, although they could be run across the ocean with three under a hard working system. But this number insures the greater safety of the ship under ordinary circumstances, and is absolutely necessary in any case of accident and danger. It is the same case with the firemen. When, in a heavy storm, the fire department may be imperfectly manned, the ship has taken one of the first chances for rendering the engines inefficient, and being finally lost. And all of these extra and indispensable _employees_ make an extra drain on the income of the ship, and add to the extreme costliness of a high adequate mail speed.

5. It is clear, then, that an adequate mail speed requires more fuel, more engineers, more firemen, more coal-stokers, and more general expense. The question of fuel is, however, alone the most important of all those affecting the attainment of high speed, and the item whose economy has been most desired and sought, both by those attempting to carry freight, and those who carry the mails and passengers. The principal points of interests concerning it are, the enormous quantity which both theory and practice show to be necessary to fast vessels; the large sum to be paid for it, and the steadily increasing price; and the paying freight room which its necessary carriage occupies. In fast steaming, the supply of coal to the furnaces frequently arrives at a point where many additional tons may be burned and yet produce no useful effect or increase of power. The draft through the furnaces and smoke stacks is so rapid and strong as to take off a vast volume of heat; and this, coupled with a large quantity of heat radiated from the various highly heated parts and surfaces, requires a consumption of fuel truly astonishing. If we reflect that at the twelve principal ports of Great Britain in the year of 1855, the tonnage entered was 6,372,301, and departed 6,426,566, equal to 12,798,867 total, and this during the war, that a large part of this was steam tonnage, and that the total imports and exports of Great Britain for 1856 were 1,600,000,000 dollars, we can somewhat appreciate the present and future uses of coal, and its inevitably large increase in price. The two hundred and seventy steamers in the British Navy, with about 50,000 aggregate horse power, consumed in 1856, according to a report made to a Committee of the "British Association for the Advancement of Science," this year, by Rear-Admiral Moorsom, 750,000 tons of coal. The difficulty and cost of mining coal, its distance from the sea-shore, and the multifarious new applications in its use among our rapidly increasing population, as well as its almost universal and increasing demand for marine purposes, all conspire to make it more costly from year to year; while, as a propelling agent, it is already beyond the reach of commercial ocean steam navigation. Coal has gone up by a steady march during the last seven years from two and a half to eight dollars per ton, which may now be regarded as a fair average price along our Atlantic seaboard. And that we may see more clearly how essentially the speed and cost of steam marine navigation depend upon the simple question of fuel alone, to say nothing further of the impeding causes heretofore mentioned, I will now present a few inquiries concerning

THE NATURAL LAWS OF RESISTANCE, POWER, AND SPEED,

WITH TABLES OF THE SAME.