Aug. 29, 1933. C. T. LUDINGTON 1,924,871 BOAT KEE Filed June 26, 1931 3. Sheets-Sheet l

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INVENTOR. 6aza's 7,402W67Ow "af. A // (8oele-- ATTORNEY. Patented Aug. 29, 1933 1924,871

UNITED STATES PATENT OFFICE 1,924,871 BOA KEE, Charles Townsend Ludington, Ardmore, Pa. Application June 26, 1931. Serial No. 546,947 10 Claims. (C. 114-130) This invention relates to boat and partic a desired lateral component of force; and many ularly to the fixed ol' adjustable keels of boats. Other objects and advantages as will become more Sail boats as developed heretofore have been apparent as the description proceeds. provided With areas of lateral resistance extend In carrying out the invention it is preferred 5 ing longitudinally of the boats and generically to utilize a keel formed of two complementary por designated as keels, which may be fixed keels or tions arranged to form a symmetrical unit of vertically adjustable keels designated as center Streamlined contour or profile when operatively boards. It is well known that the purpose of a aSSociated with each other, but each portion of keel is to prevent leeway when the vessel is work aSymmetrical airfoil contour so as individually to lO ing to Windward. The leeway represents a lateral develop a lateral component selectively directed 65 Component of the force acting on the vessel. Ac according to which of the two portions is used COrding to previous practice keels have been sub alone. Obviously the keel of this invention may stantially rectangular in cross section and there be comprised Solely of two relatively adjustable fore provided with external substantially parallel portions as of the centerboard or daggerboard 15 plane faces which have been characterized by two type, or movable elements may be operatively as 70 disadvantages. They have reduced but not elim Sociated with a fixed keel to selectively vary its inated leeway, and they form such resistance as profile Ol' Contour, or a permanently mounted de Sharply to reduce the Spaed of the vessel or craft formable keel may be provided arranged for con lupon which they are mounted. The resistance is tOur Wariation by Suitable means within the keel 20 incident to the loss of energy occasioned by the to achieve the same result. 75 formation of eddies as the planar surfaces move In the accompanying drawings: relatively to the Water. The formation of eddies Fig. 1 represents a side elevation of a diagram uses energy detracting from the longitudinal com matic Sail boat with an adjustable keel according ponent of the force acting on the vessel. The in to this invention shown in section and in full lines efficiency as to leeway of the conventional keel is With One centerboard down and the other housed 80 indicated by the established fact that the actual within the well, course of the vessel when “heading up' into the Fig. 2 represents the same as Fig. 1 except Wind or “beating to windward' is angularly di that the positions of the centerboard portions vergent from the theoretical course, delineated are reversed as to which is down and which is up, 30 by the longitudinal axis of the craft, by an angle Fig. 3 represents a horizontal section taken on aS Wide aS 5°. line 3-3 of the lowered centerboard portion It is among the objects of this invention; to of Fig. 1, . provide a vessel with a keel of high efficiency; Fig. 4 represents a similar view taken on line to provide a vessel with a keel of lower resistance 4-4 of Fig. 2, and therefore to increase the Speed of the vessel; Fig. 5 represents a fragmentary plan of a cen to provide a keel substantially precluding leeway; terboard well as disclosed in Figs. 1 and 2 show to provide a keel of such efficiency as to cause ing the streamline contour of the complementary the vessel With which it is associated to “Work' portions of the centerboard unit, more OrleSS to Windward; to provide a keel of vari Fig. 6 represents a vertical section through the 40 able contour Such as to secure a force component compleinentary halves of the centerboard unit to WindWard of Sufficient power as to nullify the according to one form of the invention, leeWard component; to provide a keel of variable Fig. 7 represents a similar vertical section contour Such as to be adjustable to its most effi cient contour to give the most efficient perform through a slightly modified form of the center ance according to the speed of the vessel With board unit, 00 Which it is aSSociated; to provide an adjustable Fig. 8 represents a diagrammatic side eleva keel of airfoil contour by which is meant a keel tion of a Sail boat with a centerboard well shown of asymmetrical croSS Section such as to secure in Section and With the adjustable keel shown a desired Windward lateral component through as of the daggerboard type, 50 the relative motion of the keel and water; to pro Fig. 9 represents a horizontal section taken on 05 vide an adjustable keel of selectively variable con line 9-9 of the daggerboard of Fig. 8, tour ranging from an asymmetrical airfoil section Fig. 10 represents a horizontal section of the through a Symmetrical streamline section to an complementary daggerboard of the pair of boards opposite asymmetrical airfoil section; to provide a used with the form of invention shown in Fig. 8, 5 5 keel of asymmetrical contour whereby to develop Fig. 11 is a diagrammatic plan of a dagger 0 2 1,924,871 board Well-plate With which is associated a fixed tudinal vertical median plane of the ship. The keel, plane face 23 of the opposite airfoil section 20 Fig. 12 represents a horizontal Section through bears the same predetermined angular relation a form of daggerboard and fixed keel assembly to the longitudinal axis of the ship (i. e. prefer 5 as provided When both daggerboards are aSSo ably parallel). When the centerboard sections 80 ciated with the fixed keel of Fig. 11, are exposed together the meeting faces 21 and Fig. 13 represents a diagrammatic front eleva 23 form the chord of the Symmetrical streamline tion, partially in Section, of a perimanent deform whole, which chord also bears the same predeter able keel in which the contour of the keel is mined angular relation to the longitudinal axis of determined by the positioning of a movable skin the ship. The normal use of such streamlined on said keel, and as illustrated provides an arched centerboard is in working before the Wind. The or cambered surface on the starboard side of double board need not be depressed very far in the keel, the Water and has the definite advantage of pre Fig. 14 represents a diagrammatic horizontal venting drift while practically eliminating eddy 5 Section taken on line 14-14 of Fig. 13 illustrating formation therefore owing to its reduced resist 90 the aSymmetrical profile of Such keel, ance securing the greatest possible Speed from Fig. 15 represents a Similar diagrammatic hori the Sail boat. ZOntal Section through the keel ShoWn in Fig. 13 In a beat to windward, however, with the Wind With the cambered surface shown as on the oppo on the port , for instance, centerboard ele 20 Site or port side of the keel from that disclosed ment 20 is pulled up into the well leaving center 95 in Figs. 13 and 14, board 18 as the exposed area of lateral resistance. Fig. 16 represents a diagrammatic horizontal Owing to the contour of element 18 there is pro Section through the keel of Fig. 13 With its normal vided an arched or cambered surface to Windward Symmetrical streamlined contour, and a substantially flat surface to leeward. 25 Fig. 17 represents a similar view with the flexi While it is known that there will be certain pres 100 ble Surface curved outwardly on both Sides of Sures exerted on the plane Sulrface 21, it is clear the keel to form a thicker streamlined keel that the cambered or arched surface 22 develops Section, a definite lateral appreciable component inci Fig. 18 represents a slightly enlarged frag dent to the relative movement of the centerboard mentary Section through the deformable keel of or adjustable keel 18 and the water. The pro 105 Fig. 13 to show one mechanism for securing va duction of such lateral component, through the riable deformation of the keel, and smooth flow of the water on the arched Surface Fig. 19 represents a similar fragmentary Sec will be readily understood by analogy with the tion illustrating the sliding connection of the principles of aerodynamics as exemplified by 35 novable covering with the fixed portion of the the flow of air by an airfoil. It has been dis 110 keel of Fig. 13. covered that the lateral component developed by Referring to Figs. 1 and 2, the sail boat the centerboard element is frequently of Such 10 has a centerboard well comprised of the fore intensity as not only to prevent leeway but posi Wall 11, wall 12, port Wall 13, and starboard tively or affirmatively to cause the boat to Work 40. Wall 14, defining a Well 15. The Walls enumerated further to windward so that the actual course 115 may delineate a rectangular well as has been traversed with relation to the Wind may be even customary in the past, or they may be so dis more acute than the angle between the longitudi posed as to conform to the contour of the center nal axis of the vessel and the Wind. Conversely, board unit to be described. For purposes of illus and obviously, with the Wind off the starboard 45 tration the Well has been disclosed as rectangular bow centerboard element 18 may be retracted, 120 in cross Section but provided With a contoured and centerboard element 20 lowered to have a baffle strip 16 as shown in Fig. 5. similar appreciable lateral component developed Mounted on the transverse pivot 17 are a pair such as substantially to nullify the leeward Com of complementary airfoil section centerboard ponent and thus to facilitate this beat to Wind 50. elements 18 and 20. These may be designated Ward. 125 respectively as the center The profile of either of the centerboard ele boards. Considering the port centerboard ele ments 18 or 20 in vertical Section is not of urgent ment 18, it will be observed that in the Section importance except in so far as the contouring shown in Fig. 3 the profile is asymmetrical and of the sections in Substantially horizontal planes 55 is characterized by the Substantially plane inner so as to be of airfoil section is facilitated. Thus 30 Surface 2 and the cambered Outer Surface 22. there is disclosed in Fig. 6 a vertical section for The complementary starboard element 20 has the the elements in which they each are tapered at substantially plane inner surface 23 and the the bottom. In Fig. 7 they are shown as Sub Outer cambered Surface 24. The arrangement is stantially untapered. 60 Such that both boards may be lowered simultane Once the principle is known there are obviously 125 ously to increase the area of lateral resistance, many modifications which may occur to those and this use of the cooperating elements presents skilled in the art. I illustrate in figs. 8, 9 and 10 a thickened centerboard of Substantially Stream a daggerboard keel. In this form the boat lo line horizontal Section as ShoWn in Fig. 5. This has the Well 15 in which the port daggerboard 65 Section obviously may be indicated by placing 24 having the airfoil contour as shown in Fig. 40 the Sections shown in FigS. 3 and 4 with their 9 similar to the Section shown in Fig. 3 is Werti respective inner plane surfaces in substantial cally slidably disposed, and held against move contact. It will be observed that the plane face ninent beyond a predetermined point by the flange 21 of board 18 is a chord line or chord of the 25 resting on of the well 15. It will be under 70 asymmetrical airfoil profile 18. This chord is a stood that a complementary daggerboard 26 may 145 Straight line passing through the entering and be disposed in operative association With board trailing edges of the airfoil Section and obviously 24 to form the streamlined whole already des bears a predetermined angular relation to the cribed. Obviously either board may be removed longitudinal axis of the ship and is preferably and the other one permitted to remain in place 5 either parallel to Or Coincident With the longi according to the direction of the Wind, with the 150 1,924,871 3 same results as previously described. Obviously entering edge 40 toward the trailing edge 42, the chord of each asymmetrical airfoil Section on one side by the section 43, and on the other and of the symmetrical streamlined unit pro by the section 44. The skin 41 may if desired vided by both boards is of the same predeter be comprised of one piece of material or of mul mined angular relation to the longitudinal axis tiple pieces according to conditions. The rear of the Ship. ward edges of sections 43 and 44 aire anchored 80 While the daggerboards 24 and 26 as illustrated to the trailing edge of the keel 35 in Such a in Fig. 8 may simply be placed back to back, manner as to permit fore and aft sliding of it is contemplated that with larger boats it may the rear edges of the sections. This attach () be desirable to provide a fixed keel for the pur ment may be accomplished in any desired man pose of lowering the center of gravity of the Whole ner such as by the provision of flanged lugs 85 by means of its own or an attached weight and or ears 45 on the inner faces of the respective with which one or the other of the daggerboalds sections engaging in undercut slots 46 formed may be operatively associated to form the Com in the permanent keel 35. plete keel. Thus, as shown in Fig. 11, the dagger Any desired means may be used to Secure board well may include a plate 19 having a fixed proper positioning of the respective sections rel keel web 29 depending therefrom and which Web ative to the permanent keel 35 and the means includes substantially plane lateral faces 27 and disclosed is to be considered as purely illustra 28 and a rounded edge 30 at its fore end and a tive and as obviously susceptible to many modi rounded edge 31 at its aft end. Daggerboard fications. A control shaft 47 having an operat openings 32 and 33 of daggerboard contour are ing device such as a crank 48 within the boat, 95 provided adjacent web 29 of the keel. So that Selec extends vertically through the stationary keel 35 tively either daggerboard 24 or 26 may be and may be provided with a Series of arms 50 pushed down through the opening 32 or 33 to rigidly engaged by the shaft 47 and disposed in sliding cooperating relation with the Web 29. longitudinally extending lateral slotS 51 formed 100 With either board in position in its appropriate in the keel 35. Each arm 50 is pivotally con opening and in abutting engagement with the nected with a link 52 pivotally connected to the flat surface of the keel web 29, it will be observed inner surface of the section 43. Any desired that the other flat keel surface Will form the fiat means, such as a friction clutch, a dog, a pawl, side of the assembled airfoil sectioned unit, the or the like 53 may be provided to the Con curved or arched surface of which Will be con trol shaft 47 in a desired position of adjust 105. prised of the rounded edges 30 and 31 and the ment. A control shaft 54 having an operating cambered surface of the associated daggerboard. arm or lever 55 is mounted rotatably in keel As shown in Fig. 12 the assembly of fixed keel 35 and has similar operative connection. With and both daggerboards in section forms a Stream the Section 44. 110 lined unit such as may be availed of when running It will be understood that with control shafts before the wind. Obviously any devices to keep 47 and 54 properly adjusted both sections 43 and each board in contact with the keel Web may be used as are found most expedient. Thus slots 44 Will be held inwardly against the outer sides n 8 may be provided on the boards arranged to of keel 35 and that the outer surfaces of Sec slide upon streamlined buttons or lugs 9 on the tions 43 and 44 conform. Substantially to the 115 Web 29. In the case of the daggerboard and keel contour of keel 35. Although the particular assembly of Figs. 11 and 12, it will be apparent profile of the permanent keel 35 of itself is rel that a straight line extending through the middle atively unimportant, as the lateral faces there of the curved entering edge 30 and the tapered of may lie in parallel planes or may be stream trailing edge 31 of the fixed web 29 comprises the lined so that the lateral faces converge toward 120 chord of predetermined angular relation to the the trailing edge, it is preferred that the keel 35 longitudinal axis for all of the forms of keel have substantially the profile illustrated in which provided by assembly and disassembly of the re each face is of a modified flattened “ogee' curve, spective daggerboards 24 and 26. as more eficient results are derived from the keel when the so called “flat' portion of the 125 It is contemplated that a fixed keel may be airfoil section has such curvature on the oppo provided which may have a flexible covering or site side to the highly arched or cambered sur be otherwise disposed so as to be selectively de face by the outwardly flexed section. It will formable to arch one side or the other or both be understood that a straight line passing and to various degrees by mechanical or other through the entering edge 40 and the trailing 130 means to Secure the desired profile of the re edge 42 will comprise a chord of all of the sym sistance area. This phase of the invention is metrical and asymmetrical contours derivable embodied in the purely illustrative form of the from the keel illustrated and that this chord disclosure of Figs. 13 to 19 inclusive. The boat obviously has a fixed predetermined angular hull 34 has the permanent keel 35 depending relation to the longitudinal axis of the ship. 135 from the center thereof and may be constructed It is of importance in connection with the or built in any manner So as to provide a per modification last described that the flexible or manent stationary inner reinforcing device. The resilient skin be susceptible to an infinite range keel 35 may join the hull 34 at right angles by of deformation in Order to obtain the profile best means of the provision of a fiat under Surface Suited for conditions existing at the moment 140 36 with relation to which the covering skin of of adjustment. It being understood in this re the invention may have sliding movement. The gard that it is preferable to have a high camber bottom of the permanent keel 35 may have the or arch when the boat is imoving slowly, but to streamlined weight o' enlargement 3 having have a low carber or arch at higher speeds. the plane upper surface 38 parallel with the The deformable permanent keel permits such 145 botton Surface 36 of the hull and also provided graduated settings as to secure high efficiency to permit sliding movement of the flexible cov under all operating conditions. eling to be described. The entering edge of the The form of the invention last described being keel 40 forms the point of attachment of a re diagrammatic in disclosure, obviously will be so silient sheet metal skin 41 extending from the constructed as regards Strength and certainty 5) 4. 1,924,871 of operation as will occur to those skilled in the initial streamlined horizontal contour with oppo alt, and Such modifications are to be construed Site Surfaces Substantially similarly cambered, as within the scope of this invention. It is of means nowable relative to the keel to vary the importance in this invention that the chord of effective horizontal contour thereof by increas alternate forms of airfoil profile of keel be an ing the camber of one lateral Surface of the keel 80 gularly fixed in order that the efficiency of the While still maintaining a streamlined contour to invention may be attained. In other Words, it Secure directionally predetermined lateral mo is important that the change of keel contour ments through hydrodynamic reaction as the from a camber oil one side to a camber on the boat moves relatively to the water substantially 10 other side be accomplished without variation in longitudinally of the keel. the angular relation of the chord of the respec 6. In boats, a centerboard nonnaily of Stream tive airfoil Sections so that the lateral compo lined Symmetrical horizontal profile with its thick nent derived fron eitheir airfoil profile is not er portion toward the entering edge thereof, and accompanied by a rearward Ol' drag Component means for varying the horizontal profile of the 5 Such as might be incident to a change of angul keel of the centerboard to provide an asymmetri 90 lar relation of the chord. In the preferred form, Cal airfoil hoi?iZOntal profile the Symmetrical and and as illustrated, the chord of all of the forms aSynnetrical profiles being relative to a chord of Symmetrical and a Syinmetrical profiles are comprised of a straight line passing through the at Substantially Zero angle relative to the longi entering and trailing edges thereof of fixed an 20 tudinal axis of the ship. gular relation to the boat. 95 I claim: 7. In combination with a boat having a longi 1. In boats, a keel, Said keel including a pair tudinal axis, a centerboard initially of stream Of complementary verticaliy Irelatively adjustable lined horizontal contour Symetrical about a elements arranged to be disposed in lowered po Vertical plane containing said axis with its thicker sition together, each element of airfoil section portion toward the entering edge, means for 100 asymmetrical relative to its chord horizontally Selectively varying the horizontal contour of Said of the element, the elements arranged to form centerboard from a fixed position of asymmetry a streamlined profile symmetrical with its chord relative to Said plane with a cambered surface in a predetermined relative position, the chord laterally on one side of said plane with its thicker 30 of said keel having the same predetermined an portion toward the entering edge, to an oppo 105 guilar relation to the longitudinal axis of the site fixed position of asymmetry relative to said boat whether the profile be asymmetrical air plane with a cambered surface on the opposite foil or Syinnaetricai Streamline. Side of Said plane With its thicker portion to 2. In boats, a centerboard well, a pair of Cen Ward the entering edge. 35. terboard elements arranged to be projected to 8. In combination, a boat, a fixed centerboard 110 gether beneath the well, said elements forming On Said boat of Streamlined horizontal contour, a unit of substantially streamined coil tour ill a flexible Skin. On Said centerboard, and means horizontal section, said elements arranged for for adjusting the relative position of the skin relative movement to expose a single element as and centerboard to provide variation in the ef 40 a resistance area, each element being of asym fective horizontal contoul of Said centerboard. 115 metrical profile with an outer al'ched Surface. 9. In boats, a keel, said keel having a chord 3. In boats, a centerboard well, a pair of cen passing through the entering and trailing edges terboard elements, means pivoting the elements in predetermined fixed angular relation to the relative to the well, the elements arranged for median vertical longitudinal plane of the boat, 45 pivoting to project simultaneously beneath the means for Selectively varying the contOul of the well, the centerboard elements each of Such pro keel relative to said chord from Symmetrical politions as to possess airfoil contour in horizontal Streamlined contOur With its thicker portion to Section when exposed beneath the well, but hav Ward the entering edge to asymmetrical airfoil ing complementary plane surfaces arranged for contour with its thicker portion toward the en 50 contacting association to enable the elements to tering edge, while maintaining Said fixed angul 125 define a streamlined section when both together lar disposition of said chord. are exposed beneath tine Well. 10. In boats, a keel, said keel having a chord 4. In a boat having a longitudinal axis, an area, comprising a straight line passing through the of lateral resistance comprising an element One entering and trailing edges of the keel in pre 55 side of which is comprised of a Substantially determined fixed anguiar relation to the median 130 planar surface any horizontal line of which is vertical longitudinal plane of the boat, means substantially parallel with said axis, the other for Selectively varying the contour of the keel side of which element comprises a laterally arched relative to said chord fron asymmetrical airfoil surface, the respective surfaces of the element contour with an arched Surface on One Side of 60 being joined at front and rear, the thicker part of said chord With its thicker portion toward the 135 the element being toward the entering edge there entering edge to asymmetrical airfoil contour of and said element ari'anged to develop an ap with an arched Surface on the other side of Said preciable lateral component in response to hydro chord. With its thicker portion toward the enter dynamic reaction as the boat moves relatively to ing edge, while maintaining Said fixed angular the water substantially longitudinally of Said disposition of Said chord. 40 axis. 5. In boats, a centerboard keel having an CHARLES TOWNSEND LUDINGTON.

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