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ne eeartininesictneenernin we BE 46 MARINE REVIEW. KNAPP ROLLER BOAT. THE INVENTOR OF A MOST REMARKABLE CRAFT OUTLINES HIS PROJECT AND MAKES STRONG CONTENTION FOR ITS PRAOTIOCABILITY. BY F A. KNAPP The troop ship which I some time ago offered to the United States government embodies to a pretty full extent the highest development that has been attained in the evolution of my invention. My engineer-- a very good man--claims a speed of at least 50 miles an hour, but in submitting the plans I made a claim simply of a speed equal to the largest present type of freighter with less power, and possibly a much higher rate of speed. I propose to carry ireight, such as grain or coal, hay or cotton, in the inner set of compartments of the cylinder, loaded as described in the specification appended to this article. The weight being thus equally distributed, I have an evenly balanced fly wheel to turn over. The vessel which I built at Toronto-- and 100 tons displacement, drawing 3 feet of ~water--was propelled six miles an hour with the power applied in a manner I never ap- proved of. 'Roller-boats" are said to be as old as the steam engine, but hitherto they have not been successful, because they were the inventions of men who may have been clever mechanics or engineers, but whe were unable to comprehend the scientific problems involved. Such craft, under certain conditions, can be propelled all right, but are not as efficient as the present type of ship and could never make any considerable speed. I have had to suffer from the difficulty of making my engineers ap- preciate the difference between power and gravity. I have always been of the opinion that speed cannot be obtained from gravity as applied in my boat, but gave way, however, as the engineers were unanimously against me. They put in practically two locomotives on a circular track, the weight climbing up inside. After two trials, they now admit I am right, and that by suspending the power and applying it to a central shaft "five times better results can be obtained." In this way it is power that does the work and not gravity, and I am satisfied that sufficient power _ can be applied to get practically unlimited speed, with a light draft, in this type of vessel, with little cost. I utilize the forces of nature, which aid me to get speed, while the present type is fighting nature. Consequently, I will not need anything like the same amount of power, with vastly greater results. The French- man Bazin, lately deceased, who has been called an eminent engineer, could not succeed in getting high speed, because of another principle involved which he appears to have ignored, if he was aware of it, viz., the resistance of the water to the forward motion of the plow. His THE KNAPP ROLLER BOAT BUILT AT TORONTO, CANADA, dises being thick at the center and thin at the circumference, always large- ly submerged, were in effect plows. He only talked of reducing skin friction, and so he would by that mode, but skin friction cuts very little figure at high rates of speed, even at 20 knots. The Campania takes 30,000 horse power to get 20 knots, while the St. Louis takes 20,000 horse power to get 19 knots. It is not skin fric- tion but the resistance to displacement of the water at the bows they must overcome, this resistance increasing as the cube of the velocity at this speed and in an unknown quantity beyond that rate. This type is built with fine lines to get the least possible resistance, but the Turbinia. with her 50 horse power per ton of displacement, rose her bow out ot the water, and her fine lines were in the air; she could not keep her bow in the water with this great resistance and therefore she might just as well have been built with a square bow. The Campania takes 214 horse power per ton of displacement, while my vessel will take about 1-9 of a Rosse meyer per ton of displacement, as proved by my experiments at oronto. My theory is that rolling broadside on over the water, I very quickly f 110 feet long, 22 feet in external diameter | [January 12, obtain a resistance which tends to lift my vessel to the surface. As water is incompreheusible and cannot be displaced quickly, I roll over it instead of through it, and it becomes a granolithic pavement, so to speak, under my vessel, because a body can only displace its own weight in water and as soon as the resistance exceeds the weight of my vessel, it must prac- tically be rolling on top. Then, like the railroad. train running up a grade, it takes less power on the level, and so I get great speed with less power. This is at a light draft of say 12 feet in a diameter of 200 feet. I am told, however, by some engineers, who either cannot compre- hend the principles involved or have not given the subject sufficient con- sideration, that such a vessel, exposing so great a surface, can never be propelled against a gale of wind, and they instance the Campania drawing 33 feet of water, or say two-thirds of her in the water, while neariy all of my boat is out of the water and exposed to the wind. Now it is not the wind that affects the Campania, but the water which strikes her with all its momentum, weighing 64 pounds to the cubic foot, the wave motion having a speed of say 70 feet per second; on the other hand, the wind is striking the one-third of her which is out of the water with a pressure of a few pounds to the square foot. Water is 825 times heavier than the air, but the Campania goes THE KNAPP BOAT IN PROCESS OF CONSTRUCTION, through it, necessarily at a reduced speed. With my vessel, the resistance of skin friction and the blow of a wave which is much below the center, knocking her legs from under her so to speak, are aids to speed. I turn the enemy into a friend and am working with nature instead of fighting her. The wind can no more stop my vessel, weighing 17,000 tons and upwards, according to her load, than it can a railroad train. __l am told again by the engineers that the weight has nothing to do with it, and that there is no power in momentum. I have given up arguing with them as hopeless, and have given them the following prob- lem: A railroad train with an ordinary mile-a-minute engine on geared trucks made a little over two miles a minute, without increasing its piston speed; assuming calm weather, it had to overcome about 3000 horse power of wind resistance; how does it do this with steam power alone? I have not so far had an answer except that if I am right "they will have to re-write their books." It does seem strange to me that men-who are trained in science should so fail to comprehend one of the greatest of nature's forces, the inertia of motion. % Steam power is able to overcome the inertia of rest, as in the railroad engine, and with less power it keeps up the inertia of motion. No ordi- nary railroad engine could possibly draw a heavy express a mile a minute with steam power alone. The mere book man seems to be away back dealing with the elementary definition of momentum, while the practical man is utilizing it as a great force. Now as to the practical aspect of my invention, apart from the question of high speed. I may say that the Toronto model has been driven six miles an hour, with one-seventh of her diameter immersed and with less than 20 horse power. This proves that my boat can go, and that I can cross the sea is unquestionable. Then what: as to her efficiency? Let us refer to her displacement at different draughts. Be- ginning with 12 feet we have 21,606 tons, and taking off her weight at 17,000 tons, we have a carrying capacity of 4,606 tons, or ereater than the Campania; at this draught she will practically run over the surface at greater speed and with very much less power than that ship requires. At 25 feet the total displacement is 55,705 tons, leaving 38,705 tons carrying capacity. The question of whether this shall be carried in the Swinging vessels or in the compartments in the cylinder is only a matter of detail. I prefer to carry it in the compartments. At 30 feet the total displacement becomes 76,595 tons--approximately 60,000 tons of coal say. or 2,000,000 bushels of wheat. And where the limit comes you can tell as well as I can. At these depths my vessel will travel, as shown by my boat at Toronto, and only requires the power necessary to turn slowly this great evenly-balanced fly-wheel. My claim is that I can drive this vessel at the latter displacement at a speed of at least 10 knots with 3.000 horse power at the very utmost. But suppose it took a far greater horse power, where is there anything to compete with it? 2 : Then I control all traffic on the seas, and the changed conditions will find their own level. It has been said that my boat can only reach this stage after much experimenting and loss of time, but I think many