US3286673A

US3286673A - Hydrofoil stabilizing means for watercraft

Info

Publication number: US3286673A
Application number: US465371A
Authority: US
Inventors: Henry W Nason
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-06-21
Filing date: 1965-06-21
Publication date: 1966-11-22
Anticipated expiration: 1983-11-22

Description

Nov. 22, 1966 H. w. NASON HYDROFOIL STABILIZING MEANS FOR WATERCRAFT Filed June 21, 96

5 Sheets-Sheet 1 Nov. 22, 1966 H. w. NASON HYDROFOIL STABILIZING MEANS FOR WATERCRAFT 5 Sheets-Sheet 2 Filed June 21, 1965 Nov. 22, 1966 H. w. NASON HYDROFOIL STABILIZING MEANS FOR WATERCRAFT 13 Sheets-Sheet 5 Filed June 21, 1965 United States Patent 3,286,673 HYDROFOIL STABILIZING MEANS FOR WATERCRAFT Henry W. Nason, 366 Farmington Ave., Plainville, Conn. Filed June 21, 1965, Ser. No. 465,371 15 Claims. (Cl. 114-665) This invention relates in general to stabilization devices for watercraft moving in a body of water and, more particularly, the invention is concerned with .a hydrofoil type of stabilizing apparatus for sailing craft, motor driven boats, and other watercraft.

Various problems are encountered in providing for stabilization of watercraft moving in a body of water, particularly where the surface of the water may be affected by wind and storms and other conditions. A watercraft may be regarded as a rigid body with three degrees of rotational freedom, namely roll, pitch, and yaw and three degrees of translational freedom herein designated as forward, lateral and vertical displacements. A stabilizing control system for limiting selected components of such motion should meet three basic requirements. First, the displacement -to be controlled should be sensed. Secondly, a force of moment is required to be generated to balance any disturbing force or moment tending to drive the sensed displacement from its normal or desired value. Third, the control system must be statically and dynamically-stable under the influence of the expected disturbances or displacements.

For sailing craft the desired value of roll is generally zero for maximum sail effectiveness, mini-mum hull drag and comfort. The pitch must be constrained to follow the general water surface profile for successful wave contouring. Yaw is usually allowed to be completely free for directional control under the influence of rudder forces.

A driving force must be provided to move the watercraft forward. In regard to sailing craft as opposed to mechanically powered boats, a lateral force is necessary to control leeway or slip downwind. For the minimization of bull drag it is desirable to reduce the wetted area and thus height stabilization or vertical positional control is advantageous.

It is, therefore, a chief object of the invention to provide improved stabilization means for controlling travel -of a watercraft on a bodyof water and, more particularly,

it 'is an object of the invention to devise a stabilizing apparatus which can be practically combined with sailing craft to quickly sense the action of force causing a change in position; which can generate an opposed balancing system of forces; and which can be made statically and dynamically stable in a sail boat environment.

With these general objectives in mind, and having regard for the problems indicated, I have devised a unique and novel arrangement of stabilization control components for use with a watercraft and particularly a watercraft of the sail boat class. The stabilization control apparatus of the invention is based on the concept of combining with the watercraft specially supported float members and hydrofoil means mechanically linked to the float members in a unique manner.

The novel concept of the invention is based on a recognition of the fact that a sailing craft equipped with side float members movably connected to rigid transverse supporting members in a manner which constrains the floats to translate with limited rotation relative to the watercraft in a vertical plane essentially parallel to a vertical plane determined by the sailing craft mast and longitudinal axis will sense roll and height variations of the sailing craft by motion of the floats in this plane. The fact has been further combined with realization of the ice large "hydrodynamic forces which may be developed on the sailing craft by a system of fully submerged controllable hydrofoil members. An important feature of this novel arrangement of parts 'is that the several components are so organized and interconnected to one another as to provide an automatic all mechanical feedback control system for generating and applying forces acting in opposed relationship to disturbance forces in order to limit roll and other changes in position of the sailing craft.

It is another specific object of the invention therefore to utilize the combined effects of float members and hydrofoil components in combination with supporting arms of relatively short length solidly anchored to the upper side of the deck of the sailing craft so that they can be permanently maintained at these points.

It is a further object of the invention to achieve multiple use of vertical hydrofoil supporting struts by utilizing the struts as dagger boards to resist leeway as Well as functioning to maintain adjustable hydrofoils submerged in water. Still another object is to provide an arrangement of hydrofoil units which permits the hydrofoils and their supporting struts to be .easily rotated out of the water in a rearward and upward manner for purposes of reducing drag forces at low speeds when the hydrofoils are ineffective, for beaching, or for safety when striking underwater objects.

Still another object is to arrange the mechanism to allow the movable floats to be fixedly positioned and for the controllable hydrofoils to be simultaneously set at an incidence yielding minimum lift and yet allowing the hydrofoil units to be rotated either into or out of the water with essentially no further incidence change.

Still another object is to construct an apparatus in which the size of the outrigger floats i reduced relative to conventional sizes of such devices and to fixedly position the floats so that they may be used in aconventional manner at low speeds whenthe hydrofoils are lifted and may be utilized as movable roll and height reference members at higher speeds when the hydrofoils are immersed and operative.

Still another object i to provide a design of a relatively deep narrow beam type hull to minimize drag and to furnish a suitable degree of leeway resistance when the hydrofoils are lifted in light wind and to further .provide for a successful wave contour in heavy seas when the hydrofoils are down and the hull is partially orcompletely lifted out of water.

The nature of the invention and its other objects and novel features will be more fully understood and appreciated from the following description of preferred embodiments of the invention shown in the accompanying drawing in which:

FIGURE 1 is a perspective view of a' sailing craft with which the stabilizing means of the invention is combined;

FIGURE 2 is a rear elevational View of the sailing craft of FIGURE 1 but further indicating the sailing craft diagrammatically in a body of water and showing float and hydrofoil components of the invention in a typical operative position in the body of water;

FIGURE 3 is a plan view indicating diagrammatically the sailing craft and the stabilizing means of the invention attached thereto;

FIGURE 4 is a side elevational view of one of the float members of the invention, together with portion of float supporting spars shown removed from the sailing craft;

FIGURE 5 is a perspective view further showing details of the control rod means for connecting a hydrofoil element with a float pull arm;

FIGURE 6 is a detail fragmentary perspective view illustrating locking means for maintaining a float member and hydrofoil element in one desired position and for varying a hydrofoil control rod to carry out a vertical displacement trim adjustment.

FIGURE 7 is a side elevational view of a float member and further illustrates a hydrofoil assembly including vertical spaced struts and hydrofoil elements supported between the struts in an operative position;

FIGURE 8 is a detail fragmentary side elevational view showing means for holding the hydrofoil assembly in a raised position;

FIGURE 9 is a side elevational view showing the hydrofoil assembly in a raised position relative to the float member;

FIGURE 10 is a view illustrating a truss arrangement for supporting the stabilizing means of the invention; and

FIGURE 11 is a view showing another modification of the invention.

The principal parts of the invention include a pair of float members connected by hinged pull arms to float supporting spars adapted to be transversely secured in parallel spaced relation at the upper side of a watercraft. Operativelyconnected to each of the floats through the hinged pull arms by means of suitable linkages are two hydrofoil units. These hydrofoil units are also secured to a hydrofoil supporting spar pivotally mounted at the upper side of the watercraft between the float supporting spars.

Considering these parts in greater detail, attention is directed to FIGURES l to 3 inclusive wherein numeral 1 denotes the hull of a Watercraft which may, for example, be of the sail boat class having a mast 2 and a boom 3. A sail 4 is attached to the mast and boom. Numeral 5 denotes a rudder operated by means of a tiller 5'. The invention will be described with specific'reference to stabilizing a sail boat although it should be understood that this is not done in any limiting sense.

In accordance with the invention, I provide two float members 9 and 9 which preferably consist of water-tight buoyant members made in the boat-like shape shown in the drawings. I further provide for locating the float members at either side of the hull in spaced relation thereto and in a position such that they may normally rest in the body of water W in which the watercraft is floating as indicated diagrammatically in FIGURE 2.

It is an essential feature of the invention that the floats be attached through a part rigidly connected to the hull in some desired manner. As one suitable means of locating the float members 9 and 9 in the position described and shown, I may employ float supporting spars 6 and 8 which are solidly secured at the upper side of the watercraft and which extend transversely thereof in parallel spaced apart relation. Preferably the float supporting spars may be arranged at points forward and aft of the cockpit area of the watercraft 1 as suggested in FIGURE 1.

An important feature of the invention consists in the manner in which the floats are attached to the rigid float supporting spars 6 and 8 and attention is directed to FIG- URES 3, 4, 5 and 6 wherein I have illustrated

pull arms

12, 12 and 13, 13'. The pull arms are pivotally connected at their upper ends to respective extremities of float supporting spars 6 and 8 in the manner more clearly shown, for example, in FIGURES 5 and 6. The lower ends of the pull arms are similarly connected to the floats 9 and 9. The connecting pivot means may in one desirable form consist in hinge members as 14, 15, 16 and 17.

It will be understood that other type devices than hinges may be employed for the pivotal attachment desired between supporting spar ends and each extremity of the pull arms. However, it is essential that whatever type of pivot means is employed, it be so chosen as to provide for the establishment of a parallelogram of

pivot axes

14, 15, 16, 17 and 14', 15', 16' and 17 which constrain the floats 9 and 9' to translate only in a plane essentially parallel to a plane determined by the mast 2 and the longitudinal 4 axes of the watercraft 1. The effect of this is that the longitudinal axes of the floats 9 and 9' are constantly maintained at a fixed angle relative to the longitudinal axis of the watercraft 1 and movement of the floats in this parallel relationship has been indicated in the drawings by arrows U and D for example in FIGURE 1.

Considering next the hydrofoil units and associated linkages earlier referred to as being operatively connected to the float pull arms, attention is again directed to FIG- URES l and 2. In the latter figure, I have illustrated the two hydrofoil units H1 and H2, and in FIGURE 1 the hydrofoil unit H1 is shown on a somewhat exaggerated scale. It will be understood that the specific sizes and shapes shown may be varied in different ways and the invention is not intended to be limited to the proportions or sizes illustrated in the drawings.

The hydrofoil units, as was the case with the floats earlier described, are required to be attached to a part which can be rigidly held in or on the hull of the boat 1 in an operative position. For this purpose I may, as suggested in FIGURE 1, provide a hydrofoil supporting spar 7 which is mounted at the upper side of the watercraft preferably by means of some suitable pivot means as, for example, hinges 7b and 70 (FIGURE 3) in close proximity to the float supporting spar 6 and in parallel relationship therewith.

An operating handle 7d is attached centrally of the supporting spar and projects rearwardly as shown in FIG- URES 1 and 3 in a position to allow an occupant in the cockpit area of the boat to rotate the supporting spar 7 into a position such as that shown in FIGURE 8 in dotted lines. In the dotted line position a fastening part 7e may be engaged with a locking rod 7 to hold the handle 7b in the raised dotted position when desired.

To secure the operating handle 70! together with the spar 7 in a fixed lowered position, I further provide a fastening 32 which can be any well-known type of clamping device anchored to the boat and adapted to overlie and adjustably secure the handle as shown.

The hydrofoil supporting spar mounted as described is in accordance with the invention, employed to locate the hydrofoil units H1 and H2 in normally vertically disposed positions in the water W preferably outside of the floats 9 and 9 as may be more clearly seen from an inspectionof FIGURE 2. Each of the two units H1 and H2 are similar in construction and similar parts are indicated by similar but primed numerals.

Considering the unit H1, numeral 11 refers to a hydrofoil element which is pivotally supported between two

vertical strut components

10 and 10a and positioned by a control linkage hereinafter described. The hydrofoil 11 is constructed of a shape to provide a wing-like surface which, when moved through the water W, develops forces whose direction and magnitude depend upon the speed of motion and the angular position of the hydrofoil with respect to the direction of movement in the well-known manner. The configuration of the hydrofoil 11 in one desired form has been indicated on a somewhat enlarged scale in FIGURE 5 and it should be understood that other shapes and proportions may be employed.

The stuts as 10 and 10a may be secured to the hydrofoil supporting spar 7 in any desired manner and in one specific instance the struts may be formed with slotted portions through which the ends of supporting spar 7 is received as shown in FIGURE 5. To provide for pivotal mounting of hydrofoil 11, I have employed pins P and P1 which are transversely mounted in a suitable bearing portion in the respective struts as shown in FIGURE 2. Other pivot arrangements may also be employed.

It is contemplated that the hydrofoil supporting spar 7, together with the attached hydrofoil units H1 and H2, will locate the hydrofoil units in a substantially vertically disposed position in the body of water W, and when the fastening part 32 is engaged this position will normally be maintained with the boat in motion.

aasaevs An important feature of the invention consists in operating control linkages for the

hydrofoils

11 and 11. The operating control linkage basically involves connecting the hydrofoil elements to respective float pull arms in such a way that change inposition of the pull arms will result in varying the position of angularity of respective hydrofoil elements and the linkage is further constructed such that a trim adjustment may be realized between the pull arms and respective hydrofoil elements. Considering the operating linkage for the hydrofoil 11, there is provided on the front portion of the hydrofoil an incidence control arm 22. This incidence control arm 22 is pivotally connected to a vertical control arm '20 in turn pivotally connected to a transverse control arm 19 adjustably secured in the pull arm 12 in an adjustment mounting 36. It will be understood the hydrofoil 11 is connected to a similar linkage attached to the pull arm 13 by means of the operating linkage described. It will be apparent that movement of a pull arm about its axis of pivoting will cause the vertical control rod 20 to move up and down and vary the position in which the hydrofoil 11 may be located at any given time when immersed in water. Considering the operation of the mechanism described, if the sailing craft in FIGURE 1 is in motion and is rolled in the direction of the arrow R the float '9'will fall in the direction of the arrow D causing a downward motion of the pull arms 1-2 and '1-2' and vertical control rod 20 in the direction of the arrow F. This downward motion of the control rod 20 causesthe hydrofoil 11 to be deflected in the direction of the arrow B thus causing a hydrodynamic force which opposes displacement in the direction of the arrow R.

From symmetry considerations it will be apparent that :the starboard float 9' and associated hydrofoil 11' will deflect in an opposite direction to the port float 9 and hydrofoil 11. This differential motion of the two hydrofoils due to roll R or L :is additive in respect to the generation of opposing roll moments on the main hull 1 transmitted by way of the struts '10, 10a, 10', 10a and hydrofoil supporting spar 7. It will be noted that the spar 7 is secured to the main hull 1 ahead of the sailing crafts center of gravity.

Next assume that the main hull 1 again has forward velocity and is moved vertically in the direction of the arrow H. Both floats 9 and 9' will fall in the direction of the arrow D which causes a downward deflection of :the associated hydrofoils 11 and 11' and results in a decrease in their 'lift. This decrease in lift of the hydrofoils 1 1 and 11' causes the main hull 1 to be accelerated in the direction of the arrow I thus opposing the original motion H. Depending upon 'the size of the force causing .the initial vertical movement H, the pull arm lengths and depression angles, the proportionality constant of the linkage made up of the vertical control rod, pivot armand incidence control arm, and the hydrofoil effectiveness, the main hull 1 will seek a change in height "relative to 'the'nominal stabilizedheight.

The apparatus of the invention further provides for adjustment of the nominal stabilized height of the -boat. This is achieved by a mechanical trim adjustment of the position of the transverse control arm 19 on the pull arm 12 as illustrated in FIGURES 5 and 6. Positioning of the transverse control arm 19 is accomplished by an adjustment arm 36 pivotally secured to the forward vpull arm 12 at point 35. The pivot axis 35 is parallel to the hinge axis 14. A slotted bar 37 attached to the adjustment trim arm 36 is secured to the pull arm 12 by an adjustment knob 38. For sailing craft this nominal stabilized height would be designed to only partially lift the main hull out of the water to compromise decreased hull resistance and safety. A narrow beam deep V cross-sectional main hull is thought to be desirable both from a performance .and construction standpoint.

When the apparatus of the invention is utilized to lift the main hull of the sailing craft out of the water to a degree wherein the inherent pitch stability due to force and aft buoyance variations on the main hull is lost, a rear fixed incidence hydrofoil 11a becomes necessary as shown in FIGURES l and 2. It is optional otherwise. A mechanically powered craft with a deep V cross-section for its main hull, which is maintained in a controlled manner at a predetermined height either partially below or slightly above the average level of small amplitude waves (less than approximately 1 foot), is capable of negotiating by countouring (following general wave profile) much larger waves encountered in severe seas.

Although the function of the roll and height stabilization features have been described in a step by step fashion and separately, it will be understood that in practice these occur simultaneously and instantaneously subject to the time lags associated with the damping and inertia characteristics of the system.

In addition, to the two primary effects of roll and height sensing and stabilization, there are some secondary effects which are believed 'to be evident from the foregoing disclosure. Assuming that the watercraft has gained forward momentum, a rearward drag force acts on each float 9 and '9. This drag force creates an unbalanced moment about the upper hinge axes 14 and 16 tendingto lift both floats out of the water in the direction 'ofthe arrow U (FIGURE 1). As the 'two floats lift there is a corresponding decrease in the upward buoyant force .of the water on the floats.

Since a component of the drag force is aiding the buoyant force which balances the float weight, the imntediate result is to rotate the floats upward and hence yield an upward angular rotation of the forward pull arms which is a function of the boat velocity and tending to increase as the boat velocity is increased.

Upward rotation of the pull arms causes each hydrofoil to be also deflected upward, which increases the :lift coeflicient and transmits a lift force to the hydrofoil supporting spar 7 and the main hull. This lift force causes the main hull 'to rise which'in turn causes a downward deflection of the foils partially cancelling the up- ;ward deflection of the foils due to the original drag force. The total effect of the drag is thus a steady upward defleclfiOn of the hydrofoils, a steady upward lift force transmitted to the main hull and a decreased displacement of the main hull.

For a sailing craft which is so designed to achieve rpitch stability only from fore and aft buoyancy change .in the 'main hull (no fixed incidence rear foil) then this drag induced hydrofoil lift force is highly beneficial. This is explained as follows. Sincethe hydrofoil sup porting spar 7 is located forward of the center of gravity of the craft a pitching moment is generated in a direction to lift the bow out of the water. This moment is :caused 'by the hydrofoil lift induced by the hydrodynamic drag force on the floats and thus increases in magnitude with increase in boat velocity through the water.

Since the sails produce a pitching moment tending to push the bow down and such a moment tends to increase with wind velocity and thus boat velocity, this secondary float drag effect opposes the sail pitch effect and is thus a favorable and highly desirable stabilizing phenomena of this invention. Recognition of the fact must be made that the technique of attaching the floats 9 on the

pull arms

12 and 13 by the hinges 14, 1'5, 16 and 17, actually prevents the floats from responding to small amplitude pitching oscillations of the main hull 1. Consequently, this drag induced lift and pitching moment will not fluctuate due to pitching oscillation of the craft and 'hence will be a relatively steadying stabilizing moment as is the destabilizing pitching moment of the sails during small amplitude pitching motion relative to the water surface.

The floats 9 in calm water at zero boat velocity seek a static position on the water determined by the balance of their buoyant force and weight due to gravity. However, in disturbed water and at boat velocities other than zero, the floats position will be perturbed by surface waves and inertial reaction forces on the hinges 15 and 17 due to roll and height acceleration of the main hull. The floats consequently are designed to have a length of at least one-half to approximately two-thirds the length of the main hull. Therefore small wave disturbances will be filtered out naturally.

I may also provide, as an aid to dampen this perturbed motion, fixed fiins 24, 24' which may be added to the floats 9 and 9' at a position below the normal water line of said floats. With this arrangement any vertical velocity of the floats relative to the water surface will result in an angle of attack variation of these fixed fins in such a direction to generate a force on said fins that opposes this vertical velocity.

The fixed fins 24, 24' can also be arranged to serve another function. By setting their fixed angle of incidence at a value other than at zero, then an upward or downward hydrodynamic force can be created which is dependent on boat velocity, and which will force the floats to seek a position above or below their normal floating position at zero speed. By design this hydrodynamic lift force can be made to aid or counteract the drag forces on the floats which in all cases causes the floats and associated hydrofoils to generate more lift.

It is, of course, undesirable in the case of a sailing craft to have the fin force counteract completely the drag force, which always lifts the float higher in the water, since this would result in losing the bow-up pitching moment on the main hull as previously discussed.

As a further aid in damping the coupled watercraft and float motion a rate damper 42 may be used shown attached to the float 9 at point 44 and the rear pull arm 12' at point 43. Motion of the floats 9 and 9' relative to the watercraft 1 will be damped by this device and its form can be any well-known type of dash-pot damper.

Means have been provided in the apparatus of the invention for limiting the angular deflection of the hydrofoils 11, 11' to prevent rotation beyond their normal design range which would be less than the stalled condition. Referring to FIGURE 4 showing a side view of float pull arm and hinge means, bolts as 25, 25' have been rigidly attached to the top surface of the float 9 at points forward of the hinge axes 15 and 17. The

bolts

25, 25 pass through holes as 26, 26' in the pull arms 12 and 12' and the bolts have adjustment nuts 27, 27' and lock nuts 28, 28' that limit the angular motion of the pull arms with respect to the floats.

By means of the action of the

arms

19, 20, 22 and the

hinges

14, 15, 16 and 17 previously discussed, and by limiting the angular motion of the pull arms 12 and 12' relative to the float, there is accomplished a limitation of the angular deflection of the hydrofoils.

The floats 9, 9' are by design able to effectively counteract heeling moments due to sail forces in light breezes by virtue of their weight and/ or buoyance alone. Thus provision has been made to simultaneously lift the hydrofoil units H1 and H2 out of the water and to temporarily secure the pull

arms

12 and 13 against rotation from a chosen position. These effects are derived by employing the handle 7d to rotate the supporting spar 7 upwardly as earlier described.

When the hydrofoil supporting spar 7 is rotated in the direction of the arrow G the struts and hydrofoils move rearward and upwardly since the struts are rigidly attached to the spar 7 and the hydrofoils are pivotally attached to the struts. This rotation should be made with a minimum of force requirements on the handle 7d for it must be accomplished by a single operator for a reasonable sized sailing craft.

As an aid in minimizing this handle force a locking bar 39 is made to engage the transverse control arm 19 in a slot 41 by a rearward motion I of the locking bar 39 in the sleeve 40 as shown on FIGURE 6. This not only fixes the forward pull arm 12 and float 9 but sets the hydrofoil element 11 at an incidence chosen to yield minimum hydrodynamic lift and thus minimizes the force transmitted to the handle 7d by way of the struts and hydrofoil supporting spar. The normal operating sequence would be to engage the transverse control arm 19 with the locking bar 39 prior to releasing the fastening 32.

Since the hinging axes 7b, P, and the pivotally mounted end points of the vertical control rod 20 form essentially a parallelogram, then there will be a minimum of angular change of the hydrofoil element 11 relative to the watercraft when the hydrofoil supporting spar 7 is rotated in the direction of the arrow G as illustrated in FIGURES 7, 8 and 9. This effect further contributes to the minimization of the force exerted on the handle 7d by the operator and allows the hydrofoil units H1 and H2 to be either lowered into or retracted from the water while the watercraft is underway.

With the hydrofoil units retracted from the water and with the floats 9 and 9' fixed relative to the watercraft then the boat functions in a manner identical to a conventional double outrigger canoe. The fastening 32 may be designed to break or release at a predetermined load as a safety feature when a strut or hydrfoil strikes a floating or submerged object. The rearward and upward motion of the hydrofoil units after the fastening 32 is broken or released is in the proper direction to minimize further damage after the first impact with the floating or submerged object. The ability to lift the hydrofoil units is a useful feature for launching the sailing craft from shallow beaches.

FIGURE 10 illustrates a truss arrangement of supporting the mast 2, the forward float supporting spar 6, and hydrofoil supporting spar 7, and includes angularly disposed truss members T1, T2, T3, T4, T5. By the utilization of such an arrangement of truss elements it is possible to decrease the structural loads sustained by the main hull 1 and would tend to allow the construction of a lighter main hull 1.

FIGURE 11 shows a modification of the major components of the apparatus. The hydrofoil supporting spar 7 is moved forward of the float supporting spar 6" and the forward pull arm 12" is extended forward beyond the hinge axis 14" to actuate the vertical control rod 20". This allows the rod 20" to be placed aft of the struct 10" axis and is thus in a less vulnerable position. The vertical control rod 20" can, of course, be enclosed within tlhe aldljacent strut in either the arrangement of FIGURE Although in the foregoing description I have illustrated preferred embodiments of the present invention, other modifications may be employed. The floats 9 may be placed either between or outboard of the struts 10 and may be constrained to translate in only the vertical dimens1ons, for example, by means of fixed bearings and slides. In addition the floats may be allowed to translate 111 two dimensions with limited movement relative to the watercraft.

In the specification the term substantially vertical as applied in reference to the disposition of the hydrofoil units is intended to include some deviations of from 20 to 30 or more. I

These and other changes and modifications may be resorted to in keeping with the scope of the appended claims.

I claim:

1. An apparatus of the class described comprising in combination a watercraft supported in a body of water, float supporting means solidly secured to the watercraft and projecting transversely outwardly from either side thereof, a pair of float members, pull arms projecting downwardly and rearwardly relative to the float supportig means, said pull arms hingedly connecting the float members to the float supporting means in spaced relation to the watercraft in said water and hydrofoil means independently connected to the watercraft and including hydrofoil elements operatively connected to the pull arms and movable therewith.

2. A structure according to claim 1 in which the float supporting means includes a pair of rigid spars occurring in spaced apart parallel relation at forward and rearward parts of the watercraft and said hingedly connected pull arms including hinge elements for connecting upper extremities of the pull arms to the rigid spars and for connecting lower extremities of the pull arms to respective floats to provide four axes of hinging at the lower ends of the pull arms which coincide with the points of intersection of four sides of a parallelogram.

3. A structure as defined in claim 1 in which the hydrofoil means includes a hydrofoil supporting spar transversely secured to the watercraft in parallel relation with the float supporting means and a pair of hydrfoil units suspended at opposite ends of the hydrofoil supporting spar in spaced relationship to the said float means and extending into the said body of water at points below the float means.

4. A structure as defined in claim 1 in which the hydrofoil means includes a hydrofoil supporting spar transversely secured to the watercraft in parallel relation with the float supporting means and a pair of hydrofoil units suspended at opposite ends of the hydrofoil supporting spar in spaced relationship to the said float means and extending into the said body of water at points below the float means, each of said hydrofoil units including a pair of vertically disposed struts spaced apart and having a hydrofoil element pivotally supported therebetween and connecting linkages extending between each of the hydrofoil elements and a respective pull arm of the floats.

5. A structure as defined in claim 1 in which the hydrofoil means includes a hydrofoil supporting spar transversely secured to the watercraft in parallel relation with the float supporting means and a pair of hydrofoil units sus pended at opposite ends of the hydrofoil supporting spar in spaced relationship to the said float means and extending into the said body of water at points below the float means, each of said hydrofoil units including a pair of vertically disposed struts spaced apart and having a hydrofoil element pivotally supported therebetween and connecting linkages extending between each of the hydrofoil elements and a respective pull arm of the floats, the said connecting linkages including an incidence control rod attached to a forward edge of a hydrofoil element, a vertical control rod pivotally connected to the incidence control rod and a pull arm actuated control rod adjustably secured to the pull arm and pivotally pinned to the vertical control rod whereby a rotative movement of a pull arm may change the position of angularity of the hydrofoil element.

6. A structure as defined in claim 1 in which the hydrofoil means includes a hydrofoil supporting spar transversely secured to the watercraft in parallel relation with the float supporting means and a pair of hydrofoil units suspended at opposite ends of the hydrofoil supporting spar in spaced relationship to the said float means and extending into the said body of water at points below the float means, each of said hydrofoil units including vertically disposed strut means having a hydrofoil element pivotally supported thereon and connecting linkages extending between each of the hydrofoil elements and a respective pull arm of the floats and each of said linkages including an incidence control arm attached to a hydrofoil element, a vertical control arm pivotally pinned to the incidence control arm and means for connecting the upper end of the vertical control arm to a respective pull arm pivot mecha- It) nism, and said pull arm pivot mechanism being adaptedto secure the vertical control rod 'in varying positions of adjustment to provide a trim adjustment for the hydrofoils.

7. A stabilizing apparatus for a boat supported in a body of water comprising a pair of float members, float supporting spars fixed to the upper 'side of the boat in parallel spaced relation and projecting outwardly attwo opposite sides, pull arms extending rearwardlyand downwardly between the floats and adjacent extremities of the float supporting arms to locate'the float members in the body of-water, means for connecting the floats to respective spar extremities in hinged relationship to provide for movement of the pull arms relative to the boat through limited arcs of rotation about axes of rotation which are parallel to the axes of the said float supporting spars, a hydrofoil supporting spar mounted at the upper side of the boat for rotative'movement between the float supporting spars and in parallel relation therewith, a pair of hydrofoil units secured to opposite ends of the hydrofoil supporting spar at either side of the boat in closely spaced relation to the said floats, each of said hydrofoil units including vertically disposed spaced apart struts extending int-o the body of water and a hydrofoil element pivotally supported between the lower extremities of the struts, each of said hydrofoil devices including control rod means connected between the hydrofoil element and an adjacent pull arm to provide for varying the position of the hydrofoil element in accordance with a change in position of a respective float to which the hydrofoil is connected.

8. A structure according to claim 7 in which the hydrofoil supporting spar is rotatable about a horizontal axis of rotation to provide for swinging the hydrofoil units rearwardly and upwardly out of said body of water into a non-operative position.

9. A structure according to claim 7 in which the hydrofoil supporting spar is rotatable about a horizontal axis of rotation to provide for swinging the hydrofoil units rearwardly and upwardly out of said body of water into a non-operative position, an operating handle secured to the said hydrofoil supporting spar and means for clamping the operating handle in a fixed position relative to the upper side of the watercraft to normally maintain the hydrofoils in a submerged position in the body of water.

10. A structure according to claim 7 in which the hydrofoil supporting spar is rotatable about a horizontal axis of rotation to provide for swinging the hydrofoil units rearwardly and upwardly out of said body of water into a non-operative position and locking means for holding the operating handle in a raised position.

11. A structure according to claim 1 in which the float members are provided with laterally extending vanes.

12. A structure according to claim 1 in which the transverse control rod may be locked to the forward float supporting spar.

13. An apparatus of the class described comprising in combination a watercraft supported in a body of water, float supporting means solidly secured to the watercraft and projecting transversely outwardly from either side thereof, a pair of float members, pull arms projecting downwardly and rearwardly relative to the float supporting means, said pull arms hingedly connecting the float members to the float supporting means in spaced relation to the watercraft in said water and hydrofoil means independently connected to the watercraft and including hydrofoil elements operatively connected to the pull arms and movable therewith, and additional hydrofoil means secured at the stern of the watercraft for cooperating with the independently connected hydrofoil means to promote stabilization of the watercraft when in motion.

14. An apparatus of the class described comprising in combination a watercraft supported in a body of water, float supporting means solidly secured to the Watercraft and projecting transversely outwardly from either side thereof, a pair of float members, pull arms projecting downwardly and rearwardly relative to the float supporting means, said pull arms hingedly connecting the float members to the float supporting means in spaced relation to the watercraft in said water and hydrofoil means independently connected to the watercraft and including hydrofoil elements operatively connected to the pull arms and movable therewith, and said pull arms and respective float members having stop elements connected therebetween to limit change in angularity of the pull arms relative to their respective floats.

15. An apparatus of the class described comprising in combination a watercraft supported in a body of water, float supporting means solidly secured to the watercraft and projecting transversely outwardly from either side thereof, a pair of float members, pull arms projecting downwardly and rearwardly relative to the float supporting means, said pull arms hingedly connecting the float members to the float supporting means in spaced relation to the watercraft in said water and hydrofoil means independently connected to the watercraft and including hydrofoil elements operatively connected to the pull arms and movable therewith, and said float members and their respective pull arms having connected therebetween damping devices for resisting rate of change of angulari'ty of the pull arms relative to their respective floats when the watercraft is moving through the said body of water.

References Cited by the Examiner UNITED STATES PATENTS 10/1945 Hook l1466.5 6/1957 Hook 114-665

Claims

1. AN APPARATUS OF THE CLASS DESCRIBED COMPRISING IN COMBINATION A WATERCRAFT SUPPORTED IN A BODY OF WATER, FLOAT SUPPORTING MEANS SOLIDLY SECURED TO THE WATERCRAFT AND PROJECTING TRANSVERSELY OUTWARDLY FROM EITHER SIDE THEREOF, A PAIR OF FLOAT MEMBERS, PULL ARMS PROJECTING DOWNWARDLY AND REARWARDLY RELATIVE TO THE FLOAT SUPPORTING MEANS, SAID PULL ARMS HINGEDLY CONNECTING THE FLOAT MEMBERS TO THE FLOAT SUPPORTING MEANS IN SPACED RELATION TO THE WATERCRAFT IN SAID WATER AND HYDROFOIL MEANS INDEPENDENTLY CONNECTED TO THE WATERCRAFT AND INCLUDING HYDROFOIL ELEMENTS OPERATIVELY CONNECTED TO THE PULL ARMS AND MOVABLE THEREWITH.