US5644A

US5644A - Improvement in apparatus for the increase of the speed of vessels

Info

Publication number: US5644A
Authority: US
Publication date: 1848-06-20
Anticipated expiration: 1865-06-20

Description

- I UNITED STATES PATENT. OFFICE.

ROBERT L. STEVENS, OF NEW YORK, N. Y., AND FRANCIS B. STEVENS, OF HOBOKEN, NEXV ERSEY.

IMPROVEMENT IN APPARATUS FOR THE INCREASE OF THE SPEED OFVESSELS.

Specification forming part of Letters Patent No; 5,644, dated J une 20, 1848.

To all whom it may concern.-

Be it known that we, ROBERT L. SrEvENs,

of the city, county, and State of New York,

and FRANCIS 13.. STEVENS, of Hoboken, in the county of Hudson, in the State of New Jersey, have invented certain Improvements in Applying Means and Apparatus to Vessels and Ships to Increase or Improve Their Speed; and we do hereby declare that the following is a full and exact description thereof.

It has long been known that the resistance that hinders or impedes the motion of vessels through the water arises from three causes Viz., the displacement of the water by the vessel, the suction (as it is termed) at the stern, produced by the motion of the vessel from the water, and, lastly, the friction produced by the immersed surface of the vessel passing through the water. WVe have not noticed the inertia of the mass to be propelled, as that. when once overcome is no longer a resistance and the propelling machinery is always constructed with aview to act regularly and keep up the acquired momentum It has also long been known that the resistance caused by the displacement, as also. that caused by the suction, could be reduced by making the Vessel sharper and of greater length in proportion to the breadth, so that the water as the vessel moves through it could be displaced by the bow more easily and fill up at the stern more gradually. The friction produced by the immersed surface of the vessel in passing through the water has frequently been looked upon as too trifling to be considered an element in calculating the resistance to the motion of vessels, and hence but few efforts have been made to reduce or modify a resistance generally supposed tov be much less than it actually is. Although the experiments made in 1796, 800., by Colonel Beaufoy upon the subject of the resistance of fluids have been considered as the basis of all other investigations upon this subject, still his experiments upon the subject of friction have not generally attracted that attention which they deserve. The amc"nt of the friction of water (against a surface of woodplaned smooth and painted) for each square foot of surface immersed in the water and the general law of its increase at differ-- ent Velocities were given by him at velocities from two to ten miles per hour. Theseexperiments on friction have been corroborated and continued by another series carefully conducted by us on the Delaware and Raritan Canal, in New Jersey, with various substances and qualities of surface and at speeds of from one mile per hour to upward of forty. By these experiments we have proved that the resistance due to friction increases as the squares of the velocities, and we have found that in the sharpest steamboats of the presentda-ythatwhich hasbeenfrequentlydeemed too inconsiderable to enter into a calculation is the largest element of resistance.

In vessels where the length is small in proportion to the breadth, and where the angles of the bow and stern are obtuse, the resistance caused by thefriction of thewater against the sides and bottom of the vessel is very small compared with the resistance caused by the displacement and the suction; but in vessels where the length is very great in pro portion to the breadth, and where the angles of the bow and stern are exceedingly sharp, the resistance caused by the friction of the water is greater than the resistance caused by the displacement and the suction. WVe have found by actual experiment that in a vessel two hundred and twenty feet long, sixteen feet wide at the water-line, molded very round, or,as it is technically termed, much out up, drawing three feet of water, and the angle of the bow six degrees, more than three quarters of the resistance to the motion of a this vessel was due to the friction of its immersed surface passing through the water. The means commonly used to diminish this friction have been to render that part of the surface of the vessel as smooth and even as possible; but we have become satisfied by ourexperiments,madewithvarioussubstances and on various surfaces, that even on the most highly-polished surfaces there is muchv friction, much more than is generally supposed. lVe have been particular in stating the existence of this friction, its magnitude, and the law of its increase, as it is the object of the principal part of our invention for improving the speed of vessels to diminish this friction, and this we do by the interposition of a stratum of atmospheric air between the immersed surface of the vessel and the water,

which we find greatly reduces the resistance arising from this friction. The air is to be applied and supplied continuously to the bottom of the vessel while it is in motion, and over the whole or as large a portion of the immersed surface as possible, and to be introduced by bellows or other blowing apparatus through pipes,channel-ways, or other conductors leading to apertures made in the sides and bottoms of vessels, or by means of pipes or other conductors running over the sides and bows of vessels and terminating in apertures or orifices distributed over the immersed surface of vessels.

It has been a maxim among naval architects and constructors that to prevent as much as possible the friction of the immersed surface of vessels against the water, it (the surface of vessels) must be made smooth but to interpose air between the surface of the Vessel and the water with the view to reduce friction we depart from this maxim, and in departing from itewe make over the entire immersed surface to be supplied with air certain irregularities, consisting of projections and recesses, which produce two useful eifectsviz., first, they make the interposition of the air more perfect by distributing it equally over the entire surface and by retaining it more perfectly and for a longer time than could otherwise be done, and, second, they produce by a well-known physical law a suction in the aper tures tending to supply the air, by which less pressure is required to supply the air tov be interposed between the surface of the vessel and the water. The most efiectual way of making the projections and recesses is to put them on in manner somewhat resembling the scales of a fish or the shingles on the roof of a house-that is, a series of inclined planes forming a slight angle with the plane of the vessels surface, and arranged in the direction of the length of the vessel, so that the summit of all the planes will be toward the stern, that when in motion the water shall by the direction of the motion pass from the tip of one scale to the tip of the next succeeding one, the air on the inclined surface of the recesses form ed-by the series of theplanes or scales having the effect to prevent the water from being forced by the pressure of the column into the recesses. The air will thus be sheltered in a measure in these recesses, and the vessel will be in contact with the water only at or near the tips of the scales, and will thus pass with a stratum of air interposed between its surface and the est part of each recess and conducted there from'pipes, channel-ways, or other conductors by holes made in the vessel or by branch pipes passing through the holes, so that the air may issue at the deepest part of the re cesses and pass alongand spread over the entire surface of the planes; but itisnot necessary, to produce a beneficial effect, that there should be an aperture in each recess as the air introduced in the recesses at the bow is carried from thence under the bottom of the vessel toward the stern and forcedup by the surrounding water into the recesses not otherwise supplied. We would observe that when there is no air in the recesses We have always found these projections and recesses detrimental, causing more resistance to the motion of the vessel than a plane sur-.

face Would do. The recesses formed between the summits of the series of planes should be divided into cells by longitudinal partitions to prevent the escape of the air at the sides. The use of projecting parts and recesses for the purpose above specified constitutes the second part of our invention.

The air applied as above described, besides reducing the friction, will have the effect to diminish the suction at the stern of .the vessel. WVe have found by experiment that if apertures are made at the stern large in size and placed closely together and communieating with the atmosphere by tubes the pressure of the atmosphere through these tubes will diminish the suction of the Vessel in its passage through the water. We place these apertures as closely together as possible Without weakening too much the structure of the vessel or reducing too much the buoyancy at the stern. The tubes or conductors leading to the atmosphere must terminate at such distance from the water as may be deemed requisite to prevent the water from overflowing them.- The use of these apertures at the stern to diminish the suction constitutes the third part of our invention.

We will now proceed to describe by reference to drawings how the surface of a vessel ,is to be constructed with the view to the application of our invention.

1n the accompanying drawings, Figure 1 is a face view of a portion of the surface of avessel on our improved plan; Fig. 2, a horizontal section taken at the line XX of Fig. 1, and Fig. 3 a vertical section taken at the line Z Z of v the same figure.

On the ordinary planking aof a vessel constructed in any desired manner, which plank vessel. These wedge likc projections, which we term the scales," because of their resemblance to the scales of a lish, overlap one anof each scale, and thespaccs between the sumi'nits constitute the reccs named inthe preceding part of this spec fication, and those recesses are lurther div de into cells ny longitudinal partitions to prevent the escape of the air at the sides. Holes fare made in the planking of the vessel, to which pipes g are fitted leading to main pipes h or channelwa vs orothernmin conductors for the supply of air, and the holes], one or more for each cell, should be made under the projecting or after partof each scale, so that the air in issuing fromthese holes may dill'use itself and cover the entire surface of each cell. instead of making the scales to overlap, their after ends maybe perpendieularto the. plane oi'thevessci, as shown in section, l ig. 4, or instead of this the recesses may be made of double and reversed inclined planes 5 1., as shown in section, Fig. 5, or therecesscs maybe formed between ribs 7 Z, the edges oi which may bi.- rounded oil, as shown in section liig. 3. lo.

these various modifications the holes ior the supply of air should be made in the most d pressed part of the recesses.

At Fig. l will be seen the side elevation ol. an entire vessel with the scales applied. This is .re 'n'oseuled as being propelled by paddlewheels; but othermodes of propelling maybe substituterfl, such as screws, sails,-&-e.

\Ve have used the inclined planes of various dimensions and have found the proper inclination to be of more inipii rtauce than the length. \Ye have used them three inc-hes long with an inclination of one in twenty-five, and eight feet long with an inclination of one in ninety, with a beneficial eilect. 'lhcsc projectionsand recesses can be forrnc'? art of the solid material of the vessel or made separate and attached. thereto. If it were judged inexpedientto make the apertures through the bottom of a vessel, tubes could be run over the sidesand introduced in the intervals between the planking and the project-ions or scales, or the vessel may be built with two thicknesses of planking and the air introduced into an interval left between them, this space being separated into divisions b v ribs running from the bow toward the stern.

The air, as above mentioned, can be applied to a vessels bottom without the intervention ot' these projections; but, excepting at very low Velocities and where the nature of the construction mag: render it necessary, we prefer the application of it by means of projections and recesses; l-ut when applied without the rcees Cswe should recommrznl that the apertures be covered \vii h plates and the air madeto issue t'"oin under the after part of these plates,or that a rib orscalobc placed in front of the aperture or apertures to reduce the pressure required to force out the air. in re spent. to the qnant-it vol air required.wehave at the peed of .ii't'tfeen flillc-- per hour used one and a half cubic feet-per minute for each .apiare foot ot. the immersed "surfacecf the ot-her,leavinga space I? under theafter part 3 vessel and have found it to produce a boneticial etfect,;and at a speed of twe i'rty-eight miles per hour we have used five cubic feet ol air per minute for each square 'foot with beneficial effect, the scales being sixteen inches long, and having an inclination of one in sixty. We have given no directions as to the blowing apparatus b: v which the air must be supplied, as this would of course vary according to circumstances, the subject of forcing air under different pressures being well understood. (faremusl. be taken that. the air be delivered at different pressures to the orifi es that are at different depths or perpeir (licular distauces from the surface of the water, so that the greater portion of the air shall not escape from a few of the apertures.

in respect to the suction. produced by the recesses, we would remark that at a speed of twelve miles per hour with scales one foot long, having an inclination of one in twentyi'ive, the water was all drawn out of a lube six inches'deep, and this suction increased ith the veloeity,so that'at a speed of twentyl'our miles per hour the water was drawn out oi? a tube thirty inches deep, and we Found that at a speed oi thirty miles an hour suilieientair was drawn under the sides and bottom of a vessel drawing one-foot of water to produce a beneficial effect without the intervention of blowing apparatus.

If it should be judged inadvisable vfrom the want of sutlicient power to force the air, or from other causes to supply the air, over the whole immersed surface of the vessel, the projections and recesses could be applied to a portion only of the surtface. This method of diminishing the friction applicable to all vessels; but it is more peculiarly adapted to vessels where the length is great in proportion to the breadth, where. the-angles of the.

bow and stern are sharp, and where the draft of water is light, so that a sui'licient supply of air can be 'readily obtaineifl.

lly the method above (lesr'ribcd the friction of the water against the whole nnnersed sun face and the suction at the stern is dimiuished, but the resistanci-i caused by the dis placement at the bow remains a fixed umb lily, the way of reducing which is by giving the vessel greater length in proportion to the .h and by reducing the angle of the This angle we recommend to be as sharp as the construction of the vessel and the purposes for which it is intended will allow.

it will be obvious that if any of the pen nianeutly-elast-icgnses be substituted in whole or in part for atmospheric air the same elli'cct will be nrin'luced.

We are aware that it has been proposed to surround the bottom of a vessel with ledges,

making lln bottom like an inverted l'migand,

lo inlrmluec air, under a pressure, into this box for the purpose of raising it to decrease the draft of water; that air has also been forced under. the water from a vessel to act as a propelling agent. We are also awarethat a patent was granted in England, in the'year 1818 to Thomas Cochraneand Alexander Gal-. loway which included among other matters the getting rid of the'gasesevolyed from the combustion in the boiler-furnacesof a steamer, or, as they'say, to allow 'suchgases to escape for dissipation byblowing them ,under water, but without intention to diminish friction and withoutany description of means by which it could produce the efli'ect; but

What-we claim as our invention, and desire to secure by Letters Patent, isa I l 1. Applying air to theimmersed surface of a vessel in motion, in manner substantially as described, and thus interpose (by acontinuous or intermittent supply) a stratum of air between the immersed surfaceor portions thereof-of 'the'vessel and the water for the purpose of reducing the friction of the water,

as described. We do not claim this application to propel the vessel, butto be used in-connection and combination with paddle-wheels, screws,-sai1s, or other propelling agent.

2,- T-herecesses on theiinmersedsurface of the Lyessel formed by the scales or otherirregulari- I ties, as described; or anything substantially the same, when combined with thesupplylut, of air, for the purpose of distributing the air and for retaining it more perfectlyand-for a longer time between the surface of the Ve -m and the water; but it are be understood 8112; we do not claim the'serefcesses independently of their use andco-nnectiou with the use of air to reduce friction; H

3. The plates over the air-apertures or the scales or ribs in front, substantially as described, to reduce the pressure required for the discharge of the air; but this we claim only when air is used as means of reducing friction.

4. The apertures made in the stern of a ves- 'sel, communicating with the atmosphere by pipes or other conductors, for the purpose 0t diminishing that resistance produced by the motion of the'vessel from the water, commonly We do not 1 claim the use of these apertures, excepting in I called the suction at "the stern.