THE LIMITS OF SPEED AT SEA.
THE coming Chicago Exhibition, which has had such an influence on the present value of the shares of the rail- ways leading to the great city of the West, has given an impulse to shipbuilding enterprise in this country which deserves more than a passing mention. The first of two enormous vessels, built specially for the Cunard Company to be in time for the rush to Chicago at the end of the summer, has this week made her trial-trip, and bids fair to fulfil her object of being the fastest, as well as the largest, of all the vessels employed on the Great Atlantic Ferry. The Cam- pania ' is a vessel of 18,000 tons displacement, 620 ft. in length, 65 ft. broad, and her engines, of 30,000 horse-power, are to drive her at an ocean speed of 22 knots per hour. This will mean a passage of something over 51 days across the Atlantic, or about
half a day less than the time taken by the 'Teutonic' and Majestic.' In order to gain this speed, her engines are 50 per cent, more powerful than those of the City of Paris,' and her length is only 80 ft. less than that of the Great Eastern.' She will carry four hundred cabin passengers, and will sail from Liverpool, the ancient head-quarters of the Atlantic passenger traffic. The object of the new ships is to cut the record of speed, which is at present held by the Teutonic,' with an average of 2035. knots per hour, and an outward passage made in five days and twenty-one hours.
The average time in the early days of the Cunard Company was about fifteen days out ; and though the speed and dimen- sions of most of the famous ships of the Atlantic fleets are familiar to many, it is often forgotten how very recent and how unforeseen was the development of modern fast-steaming. Its history might seem to belong to the story of the Atlantic liner, in which it is employed in such perfection. But, as a matter of fact, the origin of high speeds at sea, both past and present, must be sought elsewhere than in the requirements of the Transatlantic trade. The builders of small, and not of large vessels, have led in the race for speed, and it was not until the aid of the engineer had been first enlisted in the service of pleasure, and then diverted to the uses of war, that commerce stepped in and employed it with admirable skill in shortening the time of the Transatlantic passage. It was not in the Cunarders or the Inman liners, but in the 'Miranda,' a 60 ft. launch, built upon the Thames in 1870 by Mr. Thorny. croft, that the first great advance in speed was made.
When Sir Frederick Bramwell announced that he had been .carried on the Thames at Putney at the rate of seventeen miles an hour, it was seen that there were possibilities in the f attire for steam navigation beyond anything that had hitherto been conceived. The ' Miranda ' was followed by the Gitana,' a small steam-yacht in which the same inventor not only -obtained greater speed, but, by the use of forced draught in a close chamber, showed that sudden and permanent additions to the power of steaming could be produced immediately and at the pleasure of the engineer. The vessel became as docile as a locomotive in the hands of its driver. Even so, the improvement might have remained confined to pleasure- launches, until the slow process of commercial demand had gradually absorbed it, had, not the coincidence of the invention of the Whitehead torpedo created a sudden demand for swift boats from which to launch the new weapon. From that time until now, the torpedo-boat or the torpedo-cruiser has headed -the race to attain high speeds at sea, and the experiments so made have had fair and exhaustive trials before passing into general use, first in the Navy, and later in the merchant-marine. Eighteen knots, 20 knots, and 22 knots were easily attained by the earlier torpedo-boats ; and the use of forced draught, high-pressure of steam, and improved engines, which gave these results, soon became general in the Navy, and were adopted in the Atlantic liners. Speeds rose from an average of 84 knots in the earlier vessels, to the sustained ocean-speed .of 20 knots in the 'Teutonic' and 'Majestic.' In 1869, the Pressure in the boilers of the fastest ships 'Was 30 lb.; which rose to 110 lb. in the 'Oregon' and ' Etruria ' in 1883 and 1885; and has reached 150 lb. and 180 lb. in the City of Paris' and 'Teutonic.' But while the liners have reached the speeds gained by torpedo-boats ten years ago, recent improvements have again carried the last far beyond the limits set to the powers even of the new Cunarders. Boats like the Spanish ' Ariete ' class, with a displacement of 100 tons and a length of 135 ft., have run 264 knots on the measured mile, and can maintain a sea-speed, in moderate weather, of 24 knots per hour. The 'Decoy' and Daring,' flow being built for the English Navy, though larger vessels than the torpedo-boats, are to give a speed of 27 knots ; and, judging by the experience of the past, it is almost certain that the improvements which skill and knowledge have produced in the small vessels, will be imitated in the larger craft, to give the power of crossing tile Atlantic at something approach- ing 30 knots an hour. That will reduce the time from the present average of six days to an average of four days' steam- ing, unless the increase in cost be so great that passengers cannot be induced., even by a saving of one-third in the time
spent at sea, to pay the increased fare which must be de- manded.
Granting that the power of inventors and engineers to in- crease speed has by no means reached its limit, the two con- ditions which might at any moment check progress, and bring invention to a standstill, are to be found in the danger which might attend excessive speed, not within, but without the vessel, either by increasing the risk of collisions, or making it im- possible to perform duties on deck with safety and satisfaction, or in the increased cost of construction and working. The difference between 22 knots and 30 knots is probably not so wide as to increase greatly the risks already run from col- lisions. A slow vessel, sighting an Atlantic liner emerging from a fog-streak a mile off, and running at top-speed, is already so helpless, and so absolutely dependent on the good seamanship of the trained crew of the passenger-boat, that if high speeds were a menace to ocean traffic in general, the fact would be already admitted. Twenty-six knots, or something beyond 30 miles an hour, produces far less discomfort on a ship's deck than does the same speed on a locomotive. When the Ariete ' was running her full-power trial, the sensation on deck was exhilarating and pleasant, though the tingling vibration com- municated to the body by standing on such a box of machinery working at incredible speed, suggested a ride on the back of some monstrous electrical fish. The question of cost is a more serious matter. The engine-rooms, even of the existing liners, demand a staff. of 160 men and officers, making the total crew one of from 300 to 350, whose wages would be from 21,500 to £1,750 per month. When this sum is added to the expenses of maintenance, offices, insurance agency, port charges, interest on capital, and deprecia- tion, it is estimated that some £16,000 must be realised on each trip before any profit can be counted on. Fast steam- ing is frightfully expensive. It is always done under forced draught, with the maximum consumption of coal,—and even the present annual coal-bill of the Canard Company alone shows an average of nearly 1,000 tons burnt by the fleet on every day in the year. The coal consumption of the new Cunarders will amount to 400 tons a day ! On the other hand, the cost of speed decreases as the size of the ship increases. The 22-knots torpedo-boat requires engines of 10 horse-power to every ton of displacement. The Cunarder of 18,000 tons will be driven at 22 knots by machinery developing about 14 horse- power for every ton of displacement. The 18,000-tons ship is therefore some six times more economical of power than the 70-tons boat. And the fact remains that the Canard Company, in order to gain 2 knots on existing speed, have thought it within the limits of sound enterprise to build vessels at a prime cost of £200,000 more than that of the Teutonic.' That looks as if, in spite of the waste and extravagance of high speed, it can still be made to pay, so long as time is precious and sea-sickness remains a misery.
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