United States Patent 2170914

This invention relates to sailing, with particular attention to sailing into the wind, and to a rig for boats including items applicable to airplanes and gliders. An object of the invention is to improve the operation of sailing vessels by the method of use and the provision of a semi-rigid...

Rudow, Rummler
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Rudow, Rummler
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This invention relates to sailing, with particular attention to sailing into the wind, and to a rig for boats including items applicable to airplanes and gliders.

An object of the invention is to improve the operation of sailing vessels by the method of use and the provision of a semi-rigid sail, setting normally in a horizontal position but shiftable to any desired angular sailing relationship with the boat, and having a mounting which, when the sail and tiller are let go, permits the sail under the action of the wind to return to its normal horizontal setting, and head the boat into the wind. A further purpose of the invention is to 1 provide a resilient mounting for a sail and a sail construction which is responsive to vertical air waves over water waves for forward propulsion, by its form and setting, and because of being rigid throughout part of its length at the air entering edges thereof, and being graduated to maximum flexibility at the trailing end.

It is also the purpose of the invention to provide an improved frame for a lifting sail which, when close-hauled, or set for a reach, allowes the wind to exert a lifting pressure as well as a lateral pressure thereon, in any desired proportion, and when the sail is set for a run, the thrust of the wind is both forward and upward, but the frame is further serviceable for holding the sail in a partly ineffective or substantially neutral position.

Another object of the invention is to provide an improved sailing rig particularly well adapted for propelling a craft closely into the wind. An.5 other object of the invention is to provide a sail rig including resilient means for allowing a limited vibration of the sail under gusts or undulatory air effects on the sail. Another purpose of the invention is the provision of a universally jointed support for a sail which allows for lateral and fore-and-aft shifting of the sail to effect a change in the center of pressure with reference to the center of gravity, and also allows for different angular adjustments of the sail around vertical, longitudinal and transverse axes.

Another object of the invention is to provide a rig in which the sail sets horizontal when in nonsailing position and is then a canopy. A further purpose is the provision of interleaved sails which may be fanned out from shingled ineffective position into an extensive operating area. Other purposes of the invention are to avoid the customary needs for furling or reefing sails, and to render unnecessary many of the preparatory operations for sailing, and to make possible a reduction in the equipment and crew requirements commonly needed for other ships' rigs.

A further object of the invention is to provide improvements in sails to add to their utility in cooperation with power propulsion means. 6 The objects of the invention are accomplished by means of a construction as illustrated in the drawings in diagram and sketches.

Figure: shows a side view of the rig with the sail in longitudinal section. Fig. 2 is an arbitrary perspective view of a dugout with an air.screw and steering outrigged keels or ice runners and having a contractile sail frame.

Fig. 3 is a perspective view of a boat having this rig close hauled.

Fig. 4 is like Fig. 3 but illustrates a variation in sail setting for windward work.

Fig. 5 is a sketch of a two-masted vessel having the new rig in use beating to windward.

Fig. 6 is another sketch of a two masted arrangement.

Fig. 7 is a side view of a three-masted vessel hoved to.

Fig. 8 shows the ship of Fig. 7 under way.

Fig. 9 is a stern view of the three-masted boat running before the wind.

Fig. 10 shows in perspective a form of sail frame with a resilient stop for the forward sail tackle enlarged.

The sail form here illustrated and its dimensions combined with responsiveness to flexure, partly rigid construction, and a resilient pivot mounting thereof, is in imitation of natural wings.

Thus suggestions for features of sails of the character here outlined are prevalent the world over, in the sea and out of it. In the designing of the sail to at least attain a fairly efficient structure, use is made of artificial substitutes for and rearrangement of structural fetaures in real fins or wings. In following such a plan, departures from natural forms are perhaps the only possible sources of error.

Small errors in design in a boat's rig are, however, not likely to be so serious as in a rigid airplane and experimental arrangements for flying can be easily and safely tried out on a floating vessel. Such is the proposal now made.

The sail design here presented simulates to some degree a fish fin, the form of a skate, a bat, insect or bird wing and it will surely be better when so many details of structure in the models are not overlooked. Premises for performance, however, are in reliance upon what may be seen in soaring flight, such as an albatross skimming the surface of an undulating sea, and the need of 66 weight proportionate to wind velocity in soaring to windward. Also it should be borne in mind that if the wind is strong enough a ship can make headway against a current and the wind that drives it. An ice boat can go faster than the wind that drives it. A soaring bird with a wind of suitable strength can steadily sail against the wind at a land speed from zero up to what often appears to be about thirty per cent or more of the il wind velocity.

In each of these cases there is a resistance operating at right angles to the direction of travel. Leeway in the cases of the ship and ice boat is retarded by the water and the ice. In 5 the case of a soaring bird, gravity less air resistance to falling, acts at right angles to the wind when the flow is horizontal. If it were possible with a ship to make infinite tacks, its apparent course would be directly into the wind.

.0 By making a flexible wing vibrate around a forward fulcrum it is expected that an operation is brought about similar to a vast number of tacks by a ship. It also seems reasonable to assume that the velocity and static pressures on .5 the wing occur in areas favorable to windward work. A bird's body and its wings and tail are somewhat wedgeshaped in fore and aft cross section and from the center toward the tips. It is here assumed that in soaring there is velocity )0 pressure at the rear of the convex dorsal surface and a static pressure on the concave ventral surface tending to drive the wedge forward.

With a conventional ship, in tacking there is a similar condition which results in building ;5 usable pressures on the opposite sides of surfaces which are inclined to each other. These pressures are on the internal surface of a Vform. One leg of the V is the sail and the other is the vertically offset side of the hull and keel. Wind pressure on the sail and the reacting water pressure on the hull and keel cams the ship forward, but there is a vertical couple due to these offset pressure-receiving surfaces and the ship leans and to some extent slips sidewise. It is proposed in the new construction, like in lateen rigs or a lug sail, to add to this water resistance the resistance to lift and to incline the sail to lift resistance as well as to drift resistance.

an The general design of sail here illustrated is based upon the idea that, from accomplishments in bird flight, it is possible to attain artificially wing formations for utilizing the force of gravity and the action of the wind, and changes in air pressure resulting from the presence of the wing and weight to bring about forward movement of the wing into the wind. The wing form shown follows conventional designs in the form of the upper surface thereof but the lower entering surface of the wing is a flat or bevelled crescent designed to deflect some of the oncoming air downwardly, and rearwardly of this forward portion of the underneath surface of the wing, it is concave. A large portion of the wing is flexible from the rear end thereof forwardly to a rigid central area.

It is further assumed that, as the air is divided at the advancing edge of the wing, velocity and pressure changes occur, resulting in decrease in pressure on the upper and lower forward surfaces of the wing, and above normal pressure at the rear, part of the rearward frictional drag of the wind is countered.

That is, because of the decrease in pressure above the wing, the rearwardly flowing air above it is deflected downwardly towards the rear by the static pressure of the surrounding air. The lower impact receiving surface of the wing is supposed to transmit the thrust substantially at right angles to the direction of that surface, and it is expected that the downward and rearward flow caused by the forward bevelled edge of the wing, may result in a swirl of air or relatively stationary compressed wave underneath the concave surface of the wing. The static pressure of such continuously built-up wave, being above that of the surrounding air, should assist the reduced pressure above the forward part of the wing to effectively drive the wing forward against the drag of the generally rearwardly flowing air. The further assumption is made that the action of gravity tends to pull the wind downwardly and forwardly over the wave of air beneath it like a surf board on a water wave, and that this action of gravity is resiliently resisted by the reduced pressure of the air above the wing. However incomplete the theory may be, the resulting construction, when applied to a boat, allows it to point close and permits study and experiment with safety. It also allows the use of flexible wings to considerable advantage under the circumstances of undulatory air movement caused by the presence of waves on the surface of the water.

The reaction of the flexing wing is intended to provide an additional forward compelling component to the forces acting upon the wing.

However that may be, this wing is tiltable on a longitudinal axis and also turns on the axis of the mast so that it may assume the angular position of a sail close-hauled as in a lateen or a fore and aft rig.

If the wind velocity, the weight and sail area are such as to enable the craft to leave the water, or it is powered to do so, the wing may be braced to have the normal setting of wings on air craft, yet it is still shiftable in a fore and aft direction with reference to the body of the craft and may also be adjusted in a horizontal plane to increase or decrease its lifting area on one side or the other of the longitudinal axis of a fuselage. The construction is thus useful for maintaining lateral stability without the needless resistance due to the use of ailerons, and is useful for effecting increased ascension or -0 descension without losing speed because of the drag of elevators.

The relation between the center of gravity of the craft and the center of pressure on the wing may be changed to meet any requirement in that regard.

The drawings show the new construction applied to a boat. If it is a power craft relying mainly upon a motor for propulsion, the sail is serviceable to add power or for steadying in a sea-way even if confined to the ordinary dimensions of a canopy for covering the boat.

When applied to a sailboat for racing purposes the sail may be of exceptionally large area for it is set in a horizontal position on a low mast midway of the boat or forward of amidships with most of the area of the sail rearward of the mast. Part of the sail projects forward of the mast and by drawing on forward tackle the sail is tilted upon the mast into position for sailing ahead of the wind. The effect of reefing is brought about by changing the angular setting of the sail. That is, it is not tilted forwardly to the maximum extent.

The illustration, Fig. 1 shows the principal parts of the construction consisting of a sail A with a shackle B connection with a mast C. The shackle allows the sail to tilt on longitudinal and s lateral axes but otherwise retains the sail in fixed c relation with the mast. The mast is stepped in a bearing D to turn on its axis and the sail turns r with the mast because of the shackle connection therewith. The wheel E and gearing F shown I are used for turning the mast. The sail is angu- e larly adjusted on the mast by front, rear and t side sheet lines G, H and I. These lines are t roved through pulleys on the mast and cleated at J to the mast so that the whole rig may turn 1 as a unit. K and L are springs in the sheets to 'afford the sail freedom for a limited and resiliently resisted oscillatory motion around its support. Tackle and winches, useful in case of a large sail, are omitted from the drawings. The diagram shows by broken lines tilted positions of the sail. Adjustment of the sail from horizontal position toward one or the other of the broken line positions is done by turning the sail on a single axis. Other possible settings of the sail are effected by successive or simultaneous adjustments on a plurality of axes.

Figure 2 shows the improvements applied to a small boat which, due to its out-rigged keels, may be used for traveling over ice. This view also shows how the sail frame may be divided into parts which pivot together at the forward end so that the frame elements may be swung together for the purpose of furling or reefing the sail, or spread apart for the purpose of stretching the sail into maximum operative condition.

The sail I in the arrangement shown in this view is attached to arcuate arms 2 and 3. The latter are pivoted together at 4 on the end of a boom 5. A sleeve 6 slides on the boom and is pivotally connected to links or spreader arms 7 and 8 which, at their outer ends are in turn pivoted to the frame elements 2 and 3.

The sail is supported by a mast element 9 which forms an extension of a main mast 10 and has a universal joint II therewith. Tackle 12 extends between the sleeve 6 and mast element 9 for the purpose of drawing the sleeve toward the mast and spreading the toggle formed by the links 7 and 8 and thereby rocking the frame 0o members 2 and 3 forwardly around their pivot connection 4. The sail is in this manner stretched.

The mast element 9 may be rigid with the boom and extend at right-angles thereto but is illustrated as forming a bearing between two collars on the boom so that the sail may be oscillated laterally in this bearing independently of the lateral and fore-and-aft adjustment of the sail provided for by the universal joint 11.

o0 By swinging the mast element 9 to the right or left around its connection with mast 10, the center of pressure of the sail may be veered sidewise with reference to the center of gravity of the boat, even though the sail does remain sub,i5 stantially parallel with a horizontal plane. The mast 10 turns upon its axis for setting the sail in different horizontal angles with reference to the fore-and-aft center line of the boat. The sail frame and mast 9 are also tiltable forwardly on the universal joint I I to set the sail in different vertical angles. Vertical adjustment of the sail is provided for by a forward sheet 12'. By drawing inwardly on the line 12', the forward end of the sail is drawn down and the rear end of the sail is lifted. The side sheet lines 13 and 14, rhen the sail is fully spread, have connections nith the sail frame, which are located at points ubstantially in the same vertical plane with the enter of universal joint 11.

Instead of using the customary rudder arrangenent, the boat illustrated in this figure is provided vith steering keels, as dugouts generally do not tave sufficient keel, if any, needed for preventing :xcessive leeway. Another reason for equipping ;he boat with the out-rigged keels 15 is to add ;o its stability.and to support the boat and pretent it from rolling over on land or ice. The keels are made of wooden planks and provided with steel runners. They are pivoted at their forward ends on vertical shafts 16 carried at the ends of a transverse beam II attached to the hull 18. The beam is so located with reference to amidships as to bring the keel pivot 16 in position to allow the keels to function properly as rudders. The draft of a boat of this type is slight and both keels are fully immersed in the water except when the boat leans to such an extent as to lift one of them partly or wholly out of the water. A boat having a keel which remains in fixed relationship with the hull and operating in connection with a rudder which sets at an angle to the keel, of course must sacrifice speed to the extent that the rudder operates as a drag.

The boat shown in Fig. 2 is substantially flatbottomed and the keels, which are adjustable to various angles with reference to the sail setting, cooperate with the sails to control the course and balance the trim. It is not, however, necessary in the trim of the boat to sacrifice the desirability of having some weather helm. That is determined by the longitudinal position or adjustment of the keels. By setting them rearward a change from weather helm to lee helm is brought about. When under way, too much or too little weather helm may be corrected by shifting the sail between the positions indicated in Figs. 3 and 4. This brings the center of effort on the sail into different desired relationships with the center of lateral resistance on the keel or hull.

For swinging the keels 15 on their forward pivots, they are yoked together by a transverse steering bar 19. This bar may be lashed in set position by cleating down line 20 attached thereto and passing around the deck pulleys 21.

A small motor is indicated at 22 for an air screw 23. The hub of the screw is one of the gimbal rings 24 mounted by trunnions on the propeller shaft 26 to enable the propeller by centrifugal force to tend to rotate exactly true to a plane at right angles to the axis of its shaft.

The propeller is above the ice surface but if the motor is used at slow speed when the craft is in the water, and the tips of its blades strike the tops of the waves, the propeller is free to oscillate on trunnions except as the centrifugal force is built up by increased speed.

The sail forms indicated in Figures 3 and 4 are serviceable to keep rain out of an open boat when at its moorings, for the sail does not present an undue surface to the wind when lashed in its horizontal setting. It is flat from tip to tip at the trailing end. From there forwardly the flat surface changes into a curve of gradually increasing radius. It is airfoil in section from the sides inwardly as well as from the front.

For temporary and special purposes the fabric of the sail is preferably finely woven, about threeply, rubberized or water-proofed and air-tight material such as used for covering the frame structures of dirigible balloons.

The fabric, generally standard sail cloth, surrounds the sail frame and in following the form of the frame, the top and bottom coverings are spaced apart centrally and forwardly on the frame. They come together and are secured together at the rear of the sail as indicated by the area thereof having longitudinally extending battens. Forwardly the sail is reinforced by curved transverse battens. Resistance to flexure may be added at will by pumping air, or preferably helium to save weight, into the sail or into compartments thereof which are indicated in Figure 1.

The sail frame structure can be wood but the U-form illustrated in Figs. 3 and 4 may be nicely provided for by light, bent metallic tubing.

The more angular type of sail, indicated in Fig. 5, may have a somewhat similar sail frame construction as shown in Fig. 10. In this figure, the frame tubing is indicated by the numeral 27.

The tubes are welded together and the sail frame is reinforced by curved transverse wood battens 28, while the longitudinal battens 29 at the rear are carried by the sail fabric.

It is desirable to limit upward motion of the forward end of the sail so that the rear end cannot drag in the water. This is conveniently provided for by the stop 30 shown enlarged in Fig. 10. This stop by engagement with block 31 serves such purpose and by means of the compression spring 32 at its front end allows for a limited vibration of the sail as a whole around its pivotal connection with the mast.

Figures 7, 8 and 9 respectively show a vessel equipped with a plurality of such sails when it is at anchor, under sail with a cross wind, and running ahead of the wind. This interleaving of the sails as in Figure 7 shows how, with the rig compactness and low setting thereof may be had without furling operations; yet that an exceptionally large sail area- may be exposed by fanning these sails out as in Figs. 8 and 9. There is nothing to interfere with the customary shrouds and stays for the masts. The sails do not need to be hoisted to get under way. A mere lateral tilting thereof when set, as in Fig. 7, is all that is required for the purpose of leaving a mooring. When more sail area is required, the sails are hoisted as in Fig. 8 and then rolled around the mast as many degrees as required for setting the ship on its course. Each sail is like the section of a cone with a pivot on the flat surface rearward of the apex. Coming about is done by shifting the sail to more or less follow the upper surface of an imaginary cone.

In tacking the operation of adjusting the sail may be performed while the tiller is swung over by reversing the tilt of the sail, that is rolling it or letting it roll over its support along a substantially horizontal longitudinal axis or a longitudinal diagonal axis or a combination of the two and with an extremely slight or large angular motion around a vertical axis. When the sail swings over along a longitudinal axis it slices the air edgewise, and without for an instant losing pulling power. With a sail which is convex from side to side of its air entering edges or if its two sides are in angular relationship, as one side moves into a neutral position with reference to the air flow, the other side receives the impact of the air. There are various other ways of maneuvering the sail for windward work. It may be swung around a vertical axis like a square sail, but with the objection that the vessel is taken more or less aback, according to the slowness of the maneuver. The sail also may be maneuvered precisely the same as with a foreand-aft rig, particularly the lateen, as like the lateen it forms a combined main and head sail.

In that case it swings around a more or less vertical axis and takes the wind on the opposite side to which it received it on the previous tack.

A further peculiarity of the rig is the fact that it will permit a fixed adjustment of the sail which is good for running ahead of the wind, across the wind, or into it, on either the starboard or port tacks, and further the boat can run ahead of the wind backwards or tack into it backwards, or across the wind back and forth. It is possible to sail in any direction with reference to the wind direction by tilting the sail slightly downward from the horizontal at its forward end around a transverse axis, and at the same time tilting it slightly around a longitudinal axis.

Thus the rear end of the sail is somewhat lifted and inclined from side to side with reference to the deck or the horizon. This puts the sail at a working angle for any sailing direction. It then presents a near minimum area for driving ahead of the wind, but with a unidirectional constant wind pressure of high value, the sail setting is exactly right for exceptionally close performance in windward work. A wedge of compressed 80 air presses underneath the wing against weight resistance and a negative pressure is ahead of the wing. The course may be set so close to the wind that the customary lateral drift is reduced.

By manipulating the tiller the sail can be made to take the wind from the port or starboard bows and its resilient mounting and flexibility automatically results in the sail assuming an effective angle for either the port or starboard tacks.

The improved sail differs in performance and structurally from prior ones to harmonize with its mounting on a pivot in a medial point substantially in the operative plane of the sail. This makes it a balanced rig. There is the same amount of pressure on one side of its medial axis as on the other. Hence it can be maneuvered with ease in swinging it over from one tack to the other. The sail is airfoil in section from its sides inwardly. Either side may become the leading edge or both may be, depending upon the relative direction of the wind and the course of the vessel.

It has been customary to suspend sails from a yard at the head of the sail, as in square sails or from their corners and along one edge as in stay sails or try sails. One of the first reliable drawings of a sail is about 6000 years old, and shows the square sail substantially as it is today, suspended from a yard. The lateen is known to be over a thousand years old. Both of these sails would lift as well as pull, and with the few known modifications thereof would assume airfoil form, and the lateen, at least in some modern forms thereof, has decided flexibility where the air washes off the trailing end of the sail. All other sails that have come into use are substantially the same in structure and performance. The gaff or sprit sail and other more triangular sails are like square sails or lateens with the parts extending in front of the mast cut off. y( Today the standard working sail the world over is substantially the same as it was originally so far as we know.

The styles of rigging of the fore, main and mizzen masts have also remained substantially 71 the same for centuries, and were so inefficient for windward work that even up to the 18th century vessels were sometimes unable to beat to windward around Cape Horn and would pass through the Straits or would turn around and pass Cape of Good Hope in order to reach the Pacific. That goes to show that even with the most important invention man ever made with reference to his own welfare, there remained -much need of improvement even though the thousands of men who manned the shfps had before them innumeral birds showing how best to beat to windward.

By a slight rearrangement of the spars and sails it would have been possible to sail almost directly into the wind. The angular relationship of the surfaces of a bird's body and wings when in flight and soaring into the wind is such that by only a few degrees change in course, oscillation or yawing, or slight change in the direction of the wind, effective sailing surfaces are presented for windward work in different tacks.

Distinguishing features of the present invention are a resilient mounting, airfoil section from rearwardly flaring sides inwardly, and mainly over prior sails that of the medial pivot for the sail giving a balanced arrangement, and the sail is of such form that a slight angular change around a longitudinal axis sets it for different tacks, with the wind on the same surface of the sail for both tacks, or the equivalent may be accomplished by the yawing of the craft or a rocking motion of the sail around a vertical axis, to permit impingement of the wind on opposite sides of the sail for different tacks.

The thing that counts mainly with any invention is the work performed. Mere structural variations are of no moment, unless resulting in functional improvements. Thus, for measuring this or any other invention for the purposes of classification or novelty, the prime consideration is performance.

There are conveniences in sailing a vessel equipped with this rig: It is capable of withstanding ordinary blows without much trimming of sail. To a limited extent the sail may vibrate against resilient reaction; that is, adjust itself momentarily to compensate for sudden variations in pressure. It gets a good lifting purchase on the wind and serves usefully for steadying a power craft when the sea is running high.

When weather conditions are such as to ordinarily require reefing or hauling down sail, this condition may be met by changing the angle of the sail to decrease its effective area. For example, as in Fig. 3, the sail does not present the maximum entering edge to the wind as in Fig. 4, but without changing the course or changing the angular setting of the sails longitudinally, with reference to the fore-and-aft line of the boat, it may be tilted sidewise on the mast to, present less angle to the horizontal.

The sail is releasable if necessary. For example, it can by removing a pin, be permitted to blow out of the mast socket, see Fig. 2, and serve as a sea anchor or a fair raft when upsidedown on the water and some of its compartments are still holding air.

Distinguishing characteristics of this rig may be appreciated by comparison in performance with those that have been standard up to this date. Use is required of this type and others for a satisfactory understanding of the subject.

One conspicuous difference is the greater amount of lift and the place of application thereof provided by the improved sail. It holds a boat on a more even keel. Hence the efficiency of the lateral plane of the hull is maintained, power is not lost and a lee shore becomes less dangerous in a gale. The sail is not blanketed by the hull but rather more sail surface is exposed to the wind when the boat leans. The sail arrangement also provides for correct response to wind flaws, and when the lee sheet is eased the boat can hold its course and not lose much in power or speed. On a luff when occasion requires, such as when there is a gust or a shift of wind toward the quarter, there is a reduction in lift as well as in forward thrust. Since the rig provides for a decided lift and has a tendency to come to horizontal position, the craft responds favorably to a slight shift of load or list from any cause, or because of faulty handling. The lift also reduces rolling and pitching or pounding and by holding the bow up in a heavy sea the wind reduces the displacement and hence increases speed. With greater speed the craft has more power to work on. Power increases as the square of the relative motion of the sail and air. The craft is perfectly safe adrift in an open sea, for the sail naturally assumes a horizontal position if left alone and ordinarily heads the boat into the wind, or tacks into it. When the sail is cleated down in that position, or with a five or ten degree lateral and fore and aft cant from horizontal, the sail cannot rock or swing on its support, and the craft will work its way into the wind. It may, however, be steered in other directions without change of sail setting. The sail stays put. It cannot shift at all in any direction except as provision is made in its mounting for a limited resilient motion. With the tiller lashed the course may be held in a strong wind, sailing close or free, and with no danger from jibbing. Also, because of the lift there is small liklihood of the craft burying its nose. Pitching, scending, rolling, or yawing is reduced, and the danger of capsizing is remote, because the wind is working in a direction to hold the boat up. The sail need never be set at right angles to air flow, unless wanted that way perhaps because of mild air, but with a strong wind the maximum power is derived therefrom by canting the sail 450 or less from the horizontal. Then, if running dead ahead of the wind there is much less dead air cushion in front and back of the sail, as occurs for instance with the ordinary Bermuda or gaff rigs, if the latter are permitted to set at right angles to the direction of the wind.

With this principle of mounting a sail in horizontal position square over the hull and balanced from side to side, with reference to its pivot, with the center of effort rearward of that pivot, and with restraining means for preventing the sail from rocking upwardly at its forward end, a wide range of sail form and relative proportions thereof is possible without any other extensive changes. It may be made with a long entering edge and a relatively low area for windward work, or with a relatively large area like a gaff rig.

Even though a single sail is. used on a single mast it is more than equal to a wing to wing 70 setting of other sails of equal total area on a two-masted vessel, because the center of effort is higher where there is more wind and the sail may be set at a fore-and-aft angle, in which position it receives more driving power and lift and necessarily the boat is faster, all other things being equal.

In windward work the sail is set to ride down hill, utilizing weight and the inertia of lift resistance on every gust. Thus the resistance encountered, useful for windward work, is not exclusively that of the lateral profile of the hull.

It is more where it belongs in the weight of the craft. Hence, less keel or center board is required, and a corresponding reduction in weight and in skin friction becomes possible.

When the sail is applied to powered sail boats, the speed and closeness of sailing is increased decisively for many reasons. The head wind velocity may be made of any value desired, according to the power available, with a corresponding tremendous reduction in the total of water displaced. Thus resistance reduces with speed. The results are far better than a mere addition of what the boat will do under power alone, with what it will do under sail alone. By the combination of power with this particular type of lifting sail, greater speeds on the water are attained than with the old and broader combination of power and sail. The improved rig may be banked to shorten a turn. The lift and pull of the sail is increased by its arch, its inclination, and its resilient mounting.

With a standard fore-and-aft rig when a boat leans, the rudder loses much of its useful effectiveness, and tends to lift the ster, and nose down the bow, unless the wheel is shifted for a luff.

With the new rig, because of a fore-and-aft inclination of the sail, sailing before the wind becomes a fast course. Even though the boat be held dead before the wind, it is not necessary to turn away from the true course in order to reduce time for covering a specified distance in that direction.

The new product is a result of interest in the action of soaring birds in flight against or across air flow. The customary assumption that a bird works apparently directly into the wind without propelling effort by the use of upwardly directed currents such as ordinary gliding machines are dependent upon, is here supplemented, by many observed instances, with the fact of lateral tacking by birds. In some cases the movement is so slight that it is difficult to discern, and in other cases so pronounced as to be unmistakable. Lateral shifts of the air are taken advantage of.

The bird easily and automatically changes its tack with or without ascent or descent. To do so a horizontal sustaining surface oscillates mainly on horizontal axes in contrast with the vertical drive surface with a vertical axis in most boats. The wedge-shaped breastbone edge of the bird divides the current, and the form of the wing and body causes a helicoidal flow rearwardly and laterally toward the wing tips. Thus, the outer half of each wing (which may be at a negative angle while the inner half of the wing, possibly the tail, and the body are at a positive angle), is actually receiving a forward and upward pressure thrust on its under surface, while the air above the bird is correspondingly attenuated.

The helicoidal form of the wing when in soaring position may be simulated by a warped surface developed by straight lines. Hence, in the arching of the sail surface in applicant's rig, that method of construction is preferred which will result in the flow of air along straight lines in the major rear area of the sail, so as to avoid the needless development of resisting eddies.

Air is extremely elastic, and therefore when some of it is crowded in compressed form underneath and in back of the negatively set lateral portions of the wings, there is presumed to be a corresponding higher velocity and attenuation of the air passing above the wings, which results in a pull upwardly and forwardly on the marginal portions of the wings, of decisive value, but insufficient to overcome the head resistance. To make headway the bird must tack, laterally and downwardly, to develop momentum, which is expended in lift and forward motion directly into the wind or on the next tack. Such action may be difficult to obtain in artificial constructions, but can in a large measure be easily reproduced in a speed boat which is at least some sort of a connecting link between surface speed craft and air craft. The location and number of forward check lines for the sail depends upon the form of the sail-its peripheral outline-the checking means having the function of determining the axis of rotation of the sail on its mast support. Aside from its utility in sailing and permitting a ship to come to anchor or get away without much sail setting and only slight crew requirements, it adds interest to sailing and opportunity to learn in a pastime way, preliminary to or in connection with taking up the closely related subject, flying.

I claim: 1. A rigging for sailing craft, comprising a supporting hull, a mast structure mounted thereon, a sail of substantially triangular form, supported by said mast structure with a universal joint connection therewith arranged to support the sail in horizontal position centrally over the hull with the apex of the sail forward and to allow the sail to tilt down forward and to oscillate laterally, restraining means forward of the mast structure for limiting and controlling movements of the sail, said sail having its center of area rearward of said universal joint, and sheets for effecting lateral oscillation of the sail.

2. A sail frame construction comprising a pair of spars pivoted together at one end to be foldable toward each other or extended away from each other around the pivot, a sail of substantially triangular form attached along two of its sides to said spars, the third or leach side of the sail being unattached, spreader arms forming a toggle connection between said spars, means for operating the toggle connection, and a medial pivot support for the sail frame near the plane of the sail constructed for permitting adjustment of the frame from horizontal to various angular settings.

3. A sail structure comprising a substantially triangular sail, a spar extending along and attached to one edge of the sail, a spar extending along and attached to another edge of the sail, a spreading means between the two spars, a universal joint for the sail structure located between the spars near the plane of the sail, a mast by which said universal joint is carried, and means for confining the apex of the sail for limited motion forward of the mast and below the masthead. 4. A sailing craft comprising a supporting body, a mast structure mounted thereon, spars forming a supporting frame for a sail, a sail carried by said frame, a universal joint connecting said frame and mast structure, said universal joint being close to the plane of the sail, and forward of its center of area, and means for controlling and limiting movements of the sail on said universal joint whereby the sail may be swung down at its forward end from horizontal position but not up at its forward end above horizontal position, and whereby said sail may be oscillated laterally from tack to tack and receive the wind impact on the same side on both tacks.

5. A sailing craft comprising a hull equipped with a mast, a sail supported by said mast for normal horizontal setting centrally of the hull and with the center of area of the sail rearward of the mast, a universal joint between the sail and mast for permitting the sail to swing in a horizontal plane around the axis of the mast, and means for shifting the sail horizontally on the mast axis for the purpose of maintaining lateral stability.

6. A sailing vessel comprising a hull, a sail, a 20 sail frame for extending and supporting the sail in horizontal position symmetrically over the hull, a mast mounted on the hull and extending upwardly to the sail frame, a universal joint between the mast and the sail frame close to the plane of the sail and medially located with reference to the sides of the sail and rearward of the forward edge of the sail but forward of the center of area of the sail, said joint being constructed for allowing universal freedom of motion of said frame, and means for regulating and controlling all motions of said frame.

7. In a marine propulsion system including a boat having a sail and mechanical propulsion means, a mast structure carried by the boat and supporting the sail for normal horizontal setting with its edge toward the wind, said sail having less area forward of the mast than rearward of the mast for permitting the sail to have a horizontal weather-vane action, means for restraining and regulating motions of the sail so that its forward end cannot move above a horizontal plane, and means for imparting lateral oscillations to the sail around the fore-and-aft axis of the sail and for shifting the rear end of the sail laterally in order to regulate the lateral position of the center of area of the sail.

8. A sail frame structure having a rigid airentering portion and a flexible trailing portion, comprising a peripheral U-frame with a convex 9 dorsal anterior connecting structure, and a medial pivot support for the sail frame located approximately in the plane of the sail.

9. A sailing vessel having a plurality of masts differing in height each of which has pivoted at the top thereof a sail, means for setting said sails in horizontal shingled relation and for shifting said sails into fanned-out relationship.