US 2165545 A
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Description (OCR text may contain errors)
y 1939- E. G. GRANT 2,165,545
Filed April 24, 1936 3 Sheets-Sheet 1 [NVE/VTOR.
fa/muna 6. 6/4/74 ATTORNEY E. G. GRANT July 11, 1939.
Filed -Ap'ril 24, 1936 5 Sheets-Sheet 2 INVENTOR. Edmund Gwen/z WWW III
ATTORNEY E. G. GRANT July 1 1, 1939.
Filed April 24, 1936 3 Sheets-Sheet 5 INVENTOR. A obvwva G. irdflf,
Y W W W ATTORNEY.
Patented July 11, 1939 UNITED STATES PATENT OFFICE 3 Claims.
My invention relates broadly to boats and particularly to small boats of the class commonly termed dinghies, although as will become apparent hereinafter, the size of the boatsmade according to my invention may be varied between extremely wide limits.
The major object of this invention is to provide a boat structure that is exceptionally strong and durable and which will be lighter and cheaper than boats of known types. By the construction of my invention, it is possible to build a. dinghy or other relatively small boat which will be light enough for the ordinary person to handle and lift without assistance. This construction gives a boat which is sufficiently rigid so as not to be deformed, but which is nevertheless sufliciently resilient to avoid excessive stresses and strains being set up in its parts upon collision.
It is a further object of my invention to provide a boat construction which readily lends itself to quantity production methods and which has a minimum of different parts so that the dealer need not carry a large stock of unrelated parts.
It is also an object of my invention to provide a boat embodying the foregoing characteristics which is substantially puncture-proof and can therefore be used in many instances where light weight boats have heretofore been unsuited.
It is also an object of my invention to provide a novel type of veneer which is peculiarly well adapted for use in boats made according to my invention and contributes to their lightness and durability.
Another object of my invention is to provide a simple and efficient method and means for economically constructing the boats of my invention in large quantities, so that their unit cost is kept down to a minimum.
A still further object of my invention is to provide a boat using veneer planking and a novel means of joining the planks which obviates the need of screws, bolts, nails or the like.
Another feature of my invention is the provision of a novel means for joining the transom to the planking which insures a water-tight joint.
In general, the boat of my invention embodies a construction wherein the stresses and strains are taken up by fiexure throughout the midsection of the planks instead of at the joints as is customary.
In the drawings:
Fig. 1 is a side elevation of one form of dinghy made in accordance with my invention.
Fig. 2 is a top plan of the dinghy of Fig. 1.
fragmentary section taken at 8-8 of Fig. 7.
Fig 9 is a fragmentary section in perspective showing a portion of the transom and bottom of the boat of Fig. 7.
Fig. 10 is a fragmentary section showing a modified form of the joint of Fig. 8'.
Fig. 11 is a fragmentary perspective showingin detail the form of longitudinal joints used in the dinghy of Fig; 7.
Fig. 12 is a section of a novel type of veneer for use in any invention.
Fig. 13 is a side elevation partly in section showing molds for forming the dinghy. Fig. 14 is a. topplan of the molds of Fig. 13.
Fig. 15 is an enlarged section showing the means of gluing the longitudinal joints.
Fig. 16 is a cross-section taken at l6l6 of Fig. 13.
Referring now. to the drawings, and particularly to Figs. 1 to 6, wherein one embodiment of my invention is illustrated, the numerals ill indicate a plurality of ribs which may be conveniently steam bent to the desired cross-section as shown best in Fig. 3. As is customary inboat construction and seen best from Fig. 2, the beam of the boat varies from stem to bow, being a maximum somewhat aft of the midpoint between the bow piece II and the transom l2. In the form illustrated in Figs. 1 to 4, I show a double knuckle type boat and the ribs H] are therefore shaped with a substantially horizontal lower portion Illa, curved sections 1012 and substantially rectilinear. upper side sections lllc.
The upper ends of the ribs ID are fastened to gunwales l3 in conventional manner and a forward seat M which may be provided with mast partners I 5 is located in the bow of the boat and preferably supported by the forward ribs l and bow piece H. A mast step la may also be provided below the mast partners, if desired. A rowing thwart l6 and stem sheets I! are provided and may be formed in conventional manner. It
is to be understood that the particular shape, dimensions and accessories of the boat form no part of my invention.
As seen best from Figs. 3 and 4, the boat is provided with a pair of chines I8 and I9 on each side thereof extending longitudinally from bow to stem. In cross-section the chines l8 and I9 are first formed, substantially as a pentagon with a base 20 adapted to contact the ribs l0, two opposing sides cut away or recessed to form shoulders 2| and 22 into which the edges of the planking fit as described in detail hereinafter, and two adjoining exterior faces 23 and 24 opposite base 20 having their corners softened by an arc of substantial radius. The chines 8 and H! are fastened to the ribs ID by any convenient means such as screws 25 extending through the respective ribs and down into each chine.
The bottom 26, diagonal sides 21 and top sides 28 are made of thin resilient material such as veneer, which should be waterproof and is preferably of the type hereinafter described in detail. I have found that three-ply veneer is the best material for the planks 26, 21 and 28, although under certain circumstances veneer of another number of plies may be used. While veneer of two or other even number of plies might be suitable from a thickness standpoint, I prefer it made with an odd number of plies, as such construction gives maximum strength and resistance against splitting with a minimum thickness. As will be seen best from Figs. 3 and 4, the planks are secured to the ribs ID by suitable means such as screws 29 and the outer faces 23 and 24 of the chines are made slightly higher than the planks to protect the corners thereof. The outside edges of bottom plank 26 abut and rest in the shoulders 22 of the lower chines l8 and are secured thereto by suitable means such as screws 30. The diagonal side plank 2'! has one edge secured to shoulder 2| of chine l8 as by screws 3| and its other upper edge fastened in shoulder 22 of chine l9 by suitable means such as screw 32. The lower edge of top side plank 28 is held fast in shoulder 2| of chine l9 as by screws 33 and its upper edge is fastened by any suitable means between gunwale l3 and the upper end of ribs |0.
Whenever the boat is loaded or when it collides with another body such as a dock or another boat certain temporary stresses are set up in the structure tending to cause deformation thereof. With ordinary construction as now generally employed this stress and consequent deformation of the shell is taken up at the seams which are formed where the planks join each other at the chines. Obviously a flexure at the joint will have a loosening effect on the seams and continued flexure at thispoint will result in leaks along the seams. However, if the planks are made sufficiently thin the section modulus of the rib and plank at the midpoints of the planks designated on Fig. 4 by the letters A, B and C, will be substantially less than the section modulus of the ribs and chines at the joints. The lower the section modulus at a given section the greater its flexibility and by having the planks relatively thin, there will be more flexure throughout the midsection of the planks than at the chine because of the difference in section moduli. However, there is a small re duction of section at the chines due to the holes provided for the screws which fasten the planks to the chine and a plane of relative weakness is produced along the line of screws, which lessens somewhat the difference in section moduli. This weakness however, is more than compensated for by the increased stiffness given the planks at the chines by reason of the longitudinal curvature of the chines and planks, and the fact that the planks are at an angle to each other. At the ribs where the change in section modulus is gradual the compensation due to longitudinal curvature and plank angle is not so important, but between the ribs it plays an essential part, as it does throughout the shell if the ribs are eliminated. The stiffness imparted to the planks adjacent their edges and the flexibility of the midsection are accentuated by having the plank grain run longitudinally of the boat.
As previously mentioned the best material for combining strength, flexibility and lightness of weightis veneer, preferably 3-ply made according to 'my invention. When using veneer planks they are laid so that the grain of the outer plys or layers runs longitudinally of the boat, the inner ply grain then being transverse of the boat axis. By this arrangement increased flexibility at the midsection and increased stiffness at the joints are secured, and is still further increased if a veneer having its outer layers thicker than the inner or core layer is used.
In any type of boat construction, it is highly desirable to have as many parts as possible interchangeable so that the ordinary dealer need not carry an excessively large stock of different parts, and I therefore prefer to construct this form of my boat with the knuckle angles P and N substantially equal so that the chines l8 and I9 are interchangeable. In order to keep the cost of construction down to a minimum, it is essential that the various parts be of such design as to entirely eliminate handwork in their formation and I have found that this is best accomplished by having the individual knuckle angles P and N constant at every section normal to the planking throughout the lengthof the boat. By this construction, the chines can be milled out With ordinary machinery before being assembled, thus eliminating the necessity of rabbeting them out by hand throughout their length to accommodate the planking. The planking must be cut to shape anyway and I find by computing the knuckle angle with respect to the angle of flare to give a pleasing appearance and eflicient shape to the boat and then developing the other dimensions correspondingly, that it is possible to shape all of the various parts by production methods and then assemble them without further cutting or modification.
In Fig. 5 I have illustrated a modified form of dinghy embodying the foregoing principles of my invention but using only one knuckle on each side of the boat with one on the bottom. The principles of construction remain the same, strains being taken up by flexure of the sections E, F, G and H because their section modulus is considerably less than the modulus at the knuckles, this being made possible by strong thin planking such as 3-ply veneer. Likewise, the knuckle angles are the same at every section normal to the planking at the section plane so that production methods can be used in their construction. However, when using the rib and chine construction, I prefer to use the" double knuckle design because it gives a greater radius of curvature to the ribs and therefore has less stress in the longitudinal section. On the other hand, a boat could be built with more than two knuckles on each side, but unless it had an unusually broad beam, the planking would be sonar-row that flexure would not be completely absorbed in the midsections of the planks, but would be transmitted to the joints.
In the foregoing description I have described a form of boat made according to my invention and using thin planking preferably veneer, which form comprises broadly a shell formed of thin planking, chines along the seams to which the planking is fastened and a plurality of ribs to give additional rigidity and strength. In some cases I have found it very satisfactory to eliminate the ribs entirely, particularly in the double knuckle type where the curvatures are easy and the additional stiffening properties of the ribs may sometimes be dispensed with.
Another form of my invention which is an even greater departure from conventional practice is illustrated in detail in Fig. 11 of the drawings. In this type of boat it is advisable to provide steam bent ribs H! as before, but no chines at all are used. Three-ply veneer is employed and in the drawings the outer ply is designated by the numeral 40, the center ply or core by numeral 4| and the inner ply by numeral 42. As in the forms of my invention previously described various numbers of knuckles can be used and for pmposes of illustration I have shown in Fig. '7 a V-bottom boat having one knuckle on each side and one on the bottom. In that each joint is formed in the same manner, I have deemed it necessary to illustrate only one joint in Fig. 11 to be now described in detail.
The upper or side plank is designated generally by the numeral 38 and the adjoining bottom plank by the numeral 39, each of planks 38 and 39 being of veneer with plies 49, 4| and 42. In forming the joint the outer and inner plies 40 and 42 respectively of each plank 38 and 39 are cut back a suitable distance from their respective edges, say-for example from one to three inches, leaving opposing tongues =33 and 44 formed by the inner plies M of planks 3B and 39. These tongues 43 and 44 are placed in abutment and outer and innor flashing strips 45 and 46 are glued or otherwise adhesively fastened onto the tongues 43 and 44 by any suitable cement or glue. The strips 45 and 46 are of a width to exactly fill the spaces left by cutting away the outer and inner plies of the planks 38 and 39, so that when the glued joint has set, a continuous surface is formed on both the outside and inside of the boat. The flashing strips are of course bent around the joint before the glue has set and as will be apparent the outer strip 45 will be slightly wider than inner strip 45 if the plies have been cut back the same distance. By this construction all screws or other fastening means are eliminated, a smooth strong joint is obtained and a continuous shell of 3-ply veneer is formed. By eliminating the fastening screws and the holes therefor, I do away with the plane of weakness along the joint which is a characteristic of the first form of my invention illustrated.
In making veneer it is conventional practice to have the grain of the outer plies run substantially at right angles to the grain of the center ply for obvious structural reasons. As mentioned in describing the first form of my invention, I prefer to have the grain of the outer plies of my planks substantially parallel with the axis of the boat. In placing the flashing strips however, there are two main features to be considered, first adequate shear strength in the joint at the juncture of tongues 43 and 44, and second the flexibility required to bend the strips around the corner formed by the juncture of said tongues. If the grain of the strips is parallel to the edge of the planking, maximum flexibility for construction purposes is obtained, but the shear strength is minimum, and if the grain runs at right angles to the plank edge, the shear strength of the joint is maximum, but it is impossible to bend the strip around the corner without breaking. I have found that by placing the strips with their grain at a slight angle, say from 5 to 20 to their longitudinal axis, that a satisfactory compromise between these two conditions is eifected and the joint will have both adequate shear strength and flexibility for forming. I have further found that by giving theseangles reverse slopes that still further shear strength and stiifness are given to the joint. These features are best seen in Fig. 11 where it will be noted that the grain of strip 45 has a negative slope of around 10 with respect to the longitudinal axis of the strip, and that the grain of the strip 46 has a positive slope of approximately the same angle with respect to its longitudinal axis. It will be understood that these angles while preferably equal, need not be so, and that the amount of the respective angles will vary with the material being used and the exact di mensions and'shape of the boat being constructed.
The glued flashing strip type of construction gives a boat which is lighter, cheaper and stronger than the chine type previously described, which is itself lighter, cheaper and stronger than existing types of boats. Likewise, this type of boat takes up more flexure in the plank midsection and will stand more flexure at the joints, and smaller knuckle angles are therefore practical which means a wider range of shapes and designs in construction.
In Figs. 8, 9 and 10 I have illustrated a novel type of joint for accomplishing the juncture of the bottom and sides of the shell with the stern piece or transom. In all of these figures I have shown the planks and transom as made of veneer and it will be seen that they are each recessed by cutting back their respective center ply 4!. A metal strip 41 such as brass or other noncorrosive material is bent to the angle made between the adjoining faces of the transom I2 and bottom plank 39. The lengths of the angled portions of the strip 41 are such as to completely fill therecesses formed in the transom and bottom plank, and are preferably formed with teeth on their upper and lower faces adapted to be embedded in the inner and outer plies of the veneer when the boat is formed. The heel 49 of the strip 41 may be bowed out to allow the outer plys 43 to be beveled and placed flush with its outer surface as shown in Figs. 8 and 9, or it can be a simple bend entirely enclosed by the outer plies which are made to abut at the joint as illustrated in Fig. 10. The form of Figs. 8 and 9 affords more protection to the joint against sliding the boat on the sand. In each case it is preferable to fill the joint and surround the strip 41' with waterproof cement or glue to prevent leakage to the inside of the veneer. When using this type of joint I find it advisable to make the transom in sections so that the teeth 48 are always pulling substantially with the grain, as this minimizes the danger of splitting the transom.
In Fig. 12 I have illustrated a novel form of veneer which is peculiarly well adapted for boat construction where waterproof material is of course desirable. For purposes of illustration I have shown a three-ply veneer, but it will be understood of course that more or less plies can be made without varying the method. Outer plies 50 and an inner ply or core 5| are provided in conventional manner, although for boat construction I prefer to make the outer plies 50 a trifle thicker than the core 5! to give increased life and lateral flexibility with a consequent increased ability of the plank midsection to absorb all stresses by easy fiexure.
In forming the veneer of my invention I place strips of raw rubber, such for instance as the type used in retreading automobile tires, between the various plies and vulcanize the wood ply strips to the rubber by the applicaiton of heat and pressure in known manner. I have found that the amount of heat and pressure required to form a perfect bond between the wood and the rubber is much less than that necessary in the construction of present known types of veneer which use casein glue, blood glue, phenol plastics and the like.
The veneer made by my method has a great many advantages over present types, particularly for boat construction. It is of course thoroughly waterproof and much more resilient than the veneer made with binders which dry out brittle, and especially is valuable in making the flashing strip joints heretofore described. The vulcanized rubber not only makes a better and more permanent bond between the wood plies, but also with the metal joining strips 41 if these are used. Another advantage of the rubber bonded veneer resides in the ease with which the veneer or the boat made therefrom can be patched, for a quick drying rubber cement can be used which makes a Waterproof and durable patch with a minimum of effort.
Referring now to Figs. 13 to 16, it will be seen that I have provided a simple and rapid means of forming the boats of my invention with particular reference to the gluing or cementing of the flashing strips shown as a feature of the second form of boat construction hereinbefore described. The numeral 59 indicates a bottom or lower mold made of any suitable substance such as concrete for example, and the numeral 6i denotes an upper or interior mold member made of suitable material and adapted to fit inside of the mold BB as best shown by Fig. 16.
The interior of mold 60 is shaped to properly form the boat to be built and is provided with a plurality of grooves 62 positioned to receive the joints or seams of the boat, and a series of transverse grooves 63 opposite the positions of the ribs I!) of the boat, and the joint between the transom and the bottom planks. The inner mold 6| is likewise provided with longitudinal and transverse grooves numbered 64 and 65 respectively which are directly opposed to the grooves of mold 60 when the mold BI is lowered into position by any convenient means such for example the cables 66. Air bags 61 and 68 such as hoses are provided in the grooves of lower mold 6B and upper mold Bl respectively and may be made in any convenient form to fit their respective grooves.
In forming a boat by the use of the foregoing molds the outside flashing strips 45, the tongued planks for sides and bottom and the inside flashing strip 46 are placed in position in the lower mold 611 with the air bags 6! in place and only partially inflated. The inner mold 6| with its air bags 68 is then lowered into position forcing the shell to assume the position of the mold, the necessary glue or cement having been placed between the flashing strips and their respective tongues. The air bags 6! and 68 are then inflated to the required pressures to give exactly the correct forces to the joint and the whole allowed to stand until the glue has set. The upper mold is then removed and the ribs H) are put in place and the mold 6| again lowered into position with its transverse air bags inflated to glue the ribs to the shell. It will be apparent of course that numerous variations in this procedure may be followed. For instance the two steps may be combined by placing the ribs in position when the shell is formed and gluing both joints and ribs at once, or if desired separated molds may be used, one pair for gluing the seams of the shell and a second pair for gluing the ribs. However, in every case it will be found that complementary molds are necessary and preferably that they be provided with elastic means for regulating the pressure on opposite sides of the joints.
While the forms of my invention shown and described herein are now deemed the preferred forms and are fully capable of attaining the objects and providing the advantages herein mentioned, it is to be understood that they are merely illustrative of the broad principle involved in my invention as defined by the appended claims.
I claim as my invention:
1. A boat comprising a plurality of transversely extending substantially U-shaped, spaced, parallel ribs, gunwales engaging the upper ends of said ribs, a plurality of chines secured to said ribs in spaced relation and extending from the bow to stem, each of said chines including a base portion engaging said ribs, fastening means securing the base portion of the chines to the ribs, each of said chines having rabbets at each edge thereof, each of said rabbets including a base face and an edge face which are arranged at right angles to each other, the angle between the base faces of the rabbets of the chines being constant in all chines and constant throughout the length of the chines, and a plurality of planks of ply material engaging said chines, the outer edges of said planks engaging the edge faces of the chine rabbets and the inner surface of the planks at the sides engaging the base faces of the rabbets, means to hold the planks on the chines and means to secure the ribs to the planks between the chines.
2. A boat as defined in claim 1 wherein the planks of ply material are of one piece transversely of the boat between the chines.
3. A boat as defined in claim 1 in which there are a plurality of chines on each side of the boat.
EDMUND G. GRANT.