US2243247A - Folding and nonfolding marine craft - Google Patents

Description

May .27, 1941i c. H. CLARK FOLDING AND NONFOLDING MARINE CRAFT Filed sept. 25, 1959 3 sheets-sheet 1 INVENToR. CHA @L 5' HAM/5L (lA/ex May 27, 1941. c. H. CLARK FOLDING AND NONFOLDING MARINE CRAFT Filed Sept. 23, 1959 3 Sheets-Sheet 2 ww Q m Nm. WM. .l Q.\ kv... Q mm. W\ h. 'l LM. :L ma mvwl `w\ Si \NA ,Q mm S E n b mw.. uw

INVENTOR.. C'HARLgs Hasn-4L 62A RK www BY. l ATTORNEY May 27, 1941. c. H. CLARK FOLDING AND NONFOLDING MARINE CRAFT Filed Sept. 23, 1939 5 Sheets-Sheet 3 INVENTOR. CHAR/ Es #4S/ELL 2A/el( ATTORNEY lllfdldlilll I llw Patented May 27, 1941 FOLDING ANDl NONFOLDING MARINE CRAFT Charles Haskell Clark, San Francisco, Calif., assignor of one-half to Ray H. Kistler, San Francisco, Calif.

Application September 23, 1939, Serial No. 296,263

1 Claim.

The invention, in general, relates to relatively light-Weight boats. More particularly, the invention relates to kayaks and canoes and improved method of construction thereof. The present invention constitutes an improvement upon my invention disclosed and claimed in Letters Patent, No. 2,111,555, granted to me on March 22, 1938.

It is a primary object of the present invention to provide relatively inexpensive kayaks and canoes which while relatively light in weight are sufficiently rugged to withstand relatively heavy duty;

Another object of my invention is to provide marine craft of the indicated nature which are susceptible of ready handling and transportation in folded, compact form and which are adapted to be set up for use inthe water in a comparatively short time.

A still further object of the present invention is to provide marine craft of the indicated nature which are further characterized by unique and improved bows affording increased floatability and smoother movement through the water.

Another object of my present invention i-s to provide kayaks and canoes having greater buoyancy for given widths and lengths of the craft.

A still further object of the invention is to provide marine crafts of the aforementioned character wherein but a minimum cf parts are eniployed.

Another object of the invention is to providea simple, inexpensive method of fabricating kayaks and canoes for general utility as Well as for racing.

Y The foregoing as well as other objects are attained in the embodiments of my present improvement illustrated in the accompanying drawings which show preferred embodiments of a kayak and a canoe of the present improvement. It is to be understood that while I have illustrated a preferred embodiment of the present invention, as exemplified in kayaks and canoes, I am not to be limited to the precise embodiments illustrated, nor to the precise method of fabrication thereof or arrangement of parts, as the invention, as defined in the appended claim, can be embodied in a plurality and variety of forms.

Referring to the drawings:

Figure 1 is a plan View of one of the bendable sheets employed in the preferred embodiment of the lpresent invention, as exemplified in a folding kayak.

Figure 2 is a plan view of another of the bendable sheets employed in the preferred embodiment of the present invention, as exemplified in a folding kayak.

Figure 3 is a side view of a preferred embodiment of the present improvement, as exemplified in a folding kayak, this view being one-half in full elevation and the remainder in sectional elevation.

Figure 4 is a view of the folding kayak embodiment taken on the line 4--4 of Figure 3.

Figure 5 is 'a View take-n on the line 5 5 of Figure 3.

Figure 6 is a View taken on the line li-S of Figure 3.

Figure 'l is a broken plan View of a preferred embodiment of the present invention, as exemplified in a folding canoe, this View showing the adjustability of the craft from a general utility type to a racing form.

Figure 8 is a side elevational View of the embodiment illustrated in Figure '7, one half of the same being in full elevation and the` other half being in sectional elevation.

Figure 9 is a View taken on the line 9--9 of Figure 7.

Figure 10 is a view taken on the line It-l of Figure 7.

Figure 1l is a side elevation of the preferred embodiment of the present invention, as exemplified in a folding canoe, this view showing the craft in folded condition.

Figure 12 is a plan View of one of the bendable sheets employed in the preferred embodiment of the invention, as exemplified in a folding canoe.

Figure 13 is a plan view of another of the bendable sheets employed in` the preferred embodiment of the invention, as exemplified in a folding canoe.

Figure 14 is a View taken on the line lf3-i4 of Figure 1l.

Figure 15 is an enlarged detail illustrating the preferred type of joint employed between the sheets of the preferred embodiments of the present invention.

Figure 16 is a fragmentary side elevation of the preferred embodiment of the present improvement, as exemplified in a nonfolding or rigid craft.

In the folding marine craft of my present improvement, a main fold line of the craft is provided which may have either slightly, moderately or appreciabily curved extremities depending upon the depth and type of craft desired. Particular reference will hereinafter be made to this main fold line, which is designated by the reference letters X-X in Figure A3 of the drawings, not only with respect to the type of craft but also with respect to their stability and buoyancy.

In its preferred form, the marine craft of my present improvement, as exemplified in a folding kayak for general utility, preferably comprises a pair of symmetrical sections each of which comprises a side bendable sheet and a bottom bendable sheet, means hingedly connecting the bottom sheets together at their inner lateral edges on a longitudinal medial line of the hull, means hingedly connecting each side sheet to a bottom sheet affording the main fold line of the craft; each of said side sheets having a substantially straight outer lateral edge for a major portion of its length with diagonal extremities or said outer lateral edge may be slightly convex throughout its length,

and said side sheets having a longitudinally con.-

vex inner lateral edge, and each of said bottom sheets having an inner lateral edge which is substantially straight for a major portion lof its length and curved at its extremities and having an outer lateral edge which is longitudinally convex, together with a removable floor-board adapted to spread the connected bottom sheets apart to set up the craft for use in the water and simultaneously to twist said bottom sheets longitudinally so that at each end of the craft the ends of the bottom sheets lie in substantially a vertical plane and form continuations of the side sheets, and removable thwarts for increasing the beam of the craft. The racing form of kayak does not include the thwarts.

As exempliecl in a folding canoe for genf eral utility, the marine craft of my present inventio-n preferably comprises a pair of sym,- metrical sections each of which comprises a side sheet and a bottom sheet of bendable material,

means hingedly connecting said bottom sheets at their inner lateral edges on a longitudinal medial line of the craft, means hingedly connecting each side sheet to a bottom sheet to afford a main fold line of the craft; each of said side sheets having a substantially straight outer lateral edge for its entire length, an inner lateral edge which is longitudinally convex for its entire length, and diagonal ends, and each of said bottom sheets having an inner lateral edge which is substantially straight for a major portion of its length and winch is moderately curved at each extremity and having an outer lateral edge which is longitudinally convex for a portion of its length equal to the length of the convexv inner lateral edgeof each side sheet and off-set extremities equal in length to the diagonal ends of the side sheets, together with a removable oor-board adapted to spread the connected bottom sheets apart to set up the craft for use in the water and simultaneously to twist each bottom sheet longitudinally so that at each extremity of the same each bottom sheet lies substantially in a vertical plane and forms a continuation of a side sheet, and removable thwarts for increasing the beam of the craft. The racing form of canoe does not include the thwarts.

The preferred embodiment of nonfolding or rigid craft of my present improvement is in all respects the same as the folding kayak or folding canoe with the exception that the rigid or nonfolding craft are provided with continuous gunwale strips along the side sheets adjacent their outer lateral edges and coextensive therewith. i

-trated in Figure 2 of the drawings.

As illustrated in Figures 1 to 6 inclusive of the drawings, I provide a hull for the folding kayak embodiment of the present improvement which is formed from four bendable sheets II, I2, I3 and I4 to two symmetrical sections each of which includes a bottom sheet and a side sheet. The bendable sheets II to I4 inclusive are preferably cut from plywood, although any other suitable pliable material, such as waterpressed paper or galvanized iron or other pliable metal, may be employed, if desired. The bottom sheets II and I2 of the folding kayak are identical in shape and dimensions and I preferably form these bottom sheets to the shape illus- Likewise, the side sheets I3 and I 4 of the folding kayak are identical in shape and dimensions and are preferably cut to the shape illustrated in Figure 1 of the drawings. Thus, the hull of the folding kayak will take the form shown in Figure 3 of the drawings and will consist of two symmetrical sections each consisting of a pliable bottom sheet and a pliable side sheet with the bottom sheets hingedly Vconnected on a longitudinal medial line of the craft. Preferably, I employ two strips I6 and II of flexible material, such as water-impervious canvas strips, to effect the hinge joint between the bottom sheets II and I2. As illustrated, the strip I6 is fastened by any suitable means, such as by an adhesive, to the inner surfaces of the bottom sheets at their inner lateral edges. Similarly, I fasten the strip II to the outer surfaces of the bottom sheets II and I2 at their inner lateral edges. To enhance the effectiveness of the joint between these two bottom sheets, I preferably stitch the central portions of the canvas strips I6 and I'I together throughout their'lengths and also preferably quarter-round the inner lateral edges of the sheets for effectively receiving the strips, all as indicated in Figure 6 of the drawings. Moreover, I preferably slit .the inner strip I6 transversely and at spaced intervals throughout its length, as indicated by the reference numeral I8, in order to permit the draining of any moisture that might penetrate the joint and otherwise accumulate and damage the joint.

fWith particular reference to Figure 2 of the drawings, it will be observed that I preferably so form each of the bottom sheets I I and I2 of the kayak as to provide thereon an inner lateral edge which is substantially .straight for a major portion of its length, as indicated by the reference numeral I9, and which is curved at its extremities, as designated by the reference numeral 20. This inner lateral edge of the bottom sheet, as stated above, is preferably quarter-rounded. Moreover, .I so form each of the bottom sheets II and I2 as to provide thereon an outer lateral edge 2| which is longitudinally convex throughout its entire length. Each of the side panels I3 and' I4 of the kayak is preferably so formedv as tc provide thereon an inner lateral edge 26 which is longitudinally convex for its entire length, and it is to be observed that the length of the inner lateral edge 26 of each side sheet is equal in length to the outer lateral edge 2| of a,4 bottom sheet, the degree of convexity of these respective edges being the same, if the kayak vis of the foldable type, but the degree of convexity of these edges need not necessarily be the same with respect to the non-folding or rigid kayak. yThe side and bottom sheets are hingedly joined together at the inner lateral edge of each side sheet and the outer lateral edge of each bottom sheet and it is to be observed that I preferably quarter-round both the inner edges of each side sheet and the outer lateral edges of the bottom sheets in order to enhance the effectiveness of the hinge joint therebetween. Each of the side sheets I3 and I4 also is so formed as to provide thereon an outer lateral edge which is substantially straight for a major portion of its length, as indicated by the reference numeral 21, but which has diagonal extremities extending from the straight portion 21 to the ends of the sheets, as indicated by the reference numerals 28 and 29. However, the outer lateral edges of the side sheets may be made longitudinally convex for their entire length if desired.

In forming the hull of the craft of my present improvement, as exemplified in a folding kayak, I preferably first join the two bottom sheets II and I`2 together by means of the two flexible strips I6 and I1, and then fasten the side sheets to the bottom sheets employing similar exible strips. bottom sheets can first be joined together and then the two bottom sheets fastened together as above set forth. With reference to Figure 3 of the drawings, the connections between the side and bottom sheets include a pair of inner canvas strips 36 which are preferably adhesively fastened to the inner surfaces of the side and bottom sheets at their inner and outer lateral edges, respectively. Similarly, I fasten a pair of carb vas strips 31 to the outer surfaces of the side and bottom sheets at their inner and outer lat-eral edges, respectively. A water-proof adhesive preferably is employed to attach the strips 36 and 31 in position. As with the joint between the two bottom sheets, the pairs of strips 36, 31 at each side of the craft are preferably stitched together at their central portions and throughout their entire lengths and, to avoid accumulation of moisture in these joints with consequent deleterious eifect on the joints, I slit the inner strips 36 transversely at intervals throughout their lengths, as indicated by the reference numeral 38.

In accordance with the present invention, I provide means for not only rapidly setting up the craft for use in the water and permitting ready and easy collapse of the craft, but also for longitudinally twisting and outwardly bowing the bottom sheets so as to provide therefrom a bow that will out through the water with greater facility and smoother movement. These means are entirely suitable for all types of the ycraft of my present improvement and are shown in detail in Figures 7 to 10 inclusive of the drawings depicting specifically the folding canoe embodiment of the invention. As shown, I provide a oorboard 39 which is removably disposed in the hull of the craft, together with fastening means for the floor-board so arranged that the lateral edges of the floor-board will bear upon and urge the bottom `sheets apart as well as longitudinally twist and outwardly bow the same adjacent their longitudinal extremities. It may be observed that the positioning of the iioor-board within the hull of the craft also effects a rounding of the bottom sheets II and I2 at their longitudinal centers. The fastening means for the floor-board include a pair of supporting strips 4I an-d 42 which are secured to the inner surfaces of the bottom sheets at equal distances and on opposite sides of the inner lateral edges of the sheets. I also provide, in this connection, a series of plates 43 which are so arranged in opposed pairs as to It is, of course, clear that the side and be fastened to the strips 4I and 42 at spaced intervals along the strips, as shown in Figure 7 of the drawings. Each of the plates 43 is formed with an aperture 44 therein which, in conjunction with recesses formed in the strips 4I and 42 under each plate 43, provide holes for the reception of tongues 46 carried on transverse metal strips 41 and 48 fastened to the under side of the floor-board 39. To position the door-board in the hull of the craft, it is only necessary to in# sert the tongues 46 of strips 41 and 48 into the holes thus provided.

The positioning of the floor-board 39 in the hull not only spreads the inner lateral edges of the sheets II and I2 radially apart from -a longitudinal medial line through the craft, but also effects a slight rounding of the sheets laterally adjacent the longitudinal center of the craft due to the pressure exerted by the oor-board against the sheets. Moreover, the positioning of the floor-board effects a longitudinal twisting of each bottom sheet gradually and uniformly from the longitudinal center of the craft outwardly to its opposite ends. In addition, the placing of the Hoor-board into position within the hull will cause the outer surfaces of the bottom sheets adjacent their longitudinal extremities to be outwardly bowed, or convex, as indicated by reference numeral 49 in Figures 3 and 8 of the drawings. Hence, while the bottom sheets II and I2 are fiat and will lie in a horizontal position when the craft is collapsed and laid on a horizontal surface, when the craft is set up for use in the water by the insertion of the floor-board 39, these bottom sheets II and I2 will assume a definite inclination to the horizontal at the longitudinal center of the craft. And, because of the longitudinal twist given to these bottom panels by the floor-board bearing on the inner surfaces thereof, they will assume an increasingly greater angle with respect to the horizontal from their longitudinal cen-ters outwardly toward the ends o-f the sheets. If the assumed positions of these bottom sheets II and I2, when the craft is set up, be considered with respect lto the vertical rather than the horizontal, it will be observed that the bottom. sheets will be appreciably inclined away from the vertical at the longitudinal center of the craft while at each end of the craft the sheets II and I2 will be in the vertical planes drawn through the ends of the craft due to the longitudinal twisting thereof. From the foregoing, it will be appreciated that taken together the two bottom sheets II and I2 not only form the bottom of the craft but also the bow as well as the stern as a result of the twist given to the sheets. It may be observed that the angle of inclination of the two sheets II and I2 with respect to either the horizontal or to the vertical depends upon the width of each bottom sheet in the first instance, and hence the aforesaid angle of inclination can be predetermined. Moreover, the width of the floor-board 39 can be'predetermined and, thus, the longitudinal twisting of the craft when setting the same up for use in the water is predetermined. At all events, the sheets II and I2 are so twisted that the longitudinal extremities thereof will lie in vertical planes and will constitute extensions or continuations of the side sheet to which the bottom sheet is connected. In the preferred embodiment of marine craft of my present improvement, I preferably twist the bottom sheets II and I2 longitudinally to a predetermined degree in order to provide maximum stability of the craft. To this end,

each bottom sheet is so-twisted that it assumes, when the craft is set up, an angle of inclination at the longitudinal center of the craft of 65 or greater, measured from a vertical line through the exact center of the craft, the longitudinal twisting of each bottom being such that the extremities of each bottom sheet II and I2 are in vertical planes through the ends of the craft. In other words, the longitudinal twist given to each bottom sheet approaches '70 measured by the outer lateral edge of such sheets from the longitudinal center of the craft to the ends thereof. y

The improvement thus far described affords a kayak of inexpensive construction but sturdy enough to withstand relative heavy duty. Moreover, this construction provides low and streamlined bow and stern enabling smoother movement of the craft through the water and a craft that is especially suitable for racing or other sports use. To provide a folding kayak of general utility with a somewhat wider beam, it is only necessary to insert thwarts 50 in the hull fore and aft of the craft. The means for removably inserting the thwarts in position are similar for all craft constructed in accordance with the invention and are particularly described later in connection with the canoe exemplication shown in Figures 7 to 12. While the various crafts can be used effectively without keels, I preferably employ two keels on the kayak, not shown, which can conveniently be fastened to the outer surfaces of the bottom sheets I I and I2k adjacent to the outer lateral edges thereof.

As presently constructed, I preferably reinforce each end of the folding kayak exemplication of the invention with a pair of metal straps 5I which are riveted or otherwise rigidly secured to the bottom panels at their inner lateral edges overlying the strip I'I. These straps 5I preferably only extend over the curved extremities of the inner lateral edges of the bottom sheets, as depicted at the left of Figure 3 of the drawings as Well as in Figure 6 of the drawings.

In accordance withy the present improvement, as exemplified in a folding kayak, I provide a hood 52 at the bow as well as adjacent the stern of the craft, together with a spray deflector 53, as illustrated in Figures 3 and 4 of the drawings. Preferably, the hoods 52 are fabricated of waterproof canvas and are fastened to the side sheets at their outer lateral edges. Moreover, each of the hoods 52 is cut to a length that will permit folding the same in back of a deflector 53 where it is fastened to the deflector in any suitable manner, such as by means of snaps. The canvas hoods 52 are also cut to a width so that they span the hull of the craft at the bow and stern when they are drawn taut in setting up the craft for use in the water, the hoods folding upon themselves when the craft is collapsed. Each of the spray deflectors 53, preferably cut fromplywood, conveniently is formed in two sections and hingedly connected together by means of a short canvas strip 54 applied by a suitable water-proof adhesive. As in the case of the other flexible or hinge joints of the craft, I preferably quarterround the inner lateral edges of the two sections of each spray deflector 53'in order to enhance iCI! enhance the rigidity of the craft at the ends, I:

provide metal hinges 56, as shown in Figure 3 of the drawings. These metal hinges likewise are not essential. Reinforcing strips 57 and 58 are provided fore and aft of the craft extending interiorly of the hull from the metal hinges 5S, see Figure 7 of the drawings.

The folding canoe of myv present-improvement is closely similar to the folding kayak in ysfo-far as method of construction is concerned and provision of a main fold, but differs from the kayak in the shape of the side and bottom sheets. As: illustrated particularly in Figures 7 to 1,5 of the drawings, I provide a folding canoe hull which ls formed to two symmetrical sections including a pair of bottom bendable sheets II and I2 and .a pair of side bendable sheets I3 and I4, all sheets preferably being cut from plywood .although they may be made from any other' suitable pliable material, such as water-proof pressed paper or galvanized iron or other bendable metal.' The two bottom sheets are hingedly connected together along a longitudin-al medial line of the craft at their inner lateral edges by' means of two strips I6 and I'I of water-impervious canvas, the inner strip preferably lbeing slitted transversely at spaced intervals throughout its length, as indicated as I8, in order to prevent accumulation of moisture that might pent'etrate the 10m Each of the sheets Il and I2 for the folding canoe is cut to the same shape and dimensions and preferably takes the shape illustrated inl tom sheet is so cut as to provide thereon-ani inner lateral edge which is' substantially straight for a major portion of its length, as indicated by reference numeral I9, and which is moderately curved at each extremity, as indicated by the reference numeral 20. Moreover, the bottom sheets are so cut that there is provided thereon an outer lateral e'dge which is longitudinally con- Vex for a major portion of its length, as indicated by the reference numeral 2|, this edge having two off-set portions 22 and 23 ext-ending from the ends of the -convex 4portion 2| which in turn merge with diagonal extremitiesf24 )and 25,l re-l spectively, extending to the ends ofthe sheets. In Figure 12 of the drawings, I have depicted the preferred form of side sheets for vthe folding canoe,- these side sheets being identical in shape and dimensions. As shown, each vside sheet'pref erably is so cut that there is provided thereon a longitudinally convex inner lateral edge -26 which is convex for its entire length, and this edge is equal in length land -cut to the same degree of convexity as the convex -portion 2| ofthe bottom sheets. Moreover, each side sheetl is so vcut as to provide thereon ya substantially straight outer lateral edge 2l, and each side sheet has diagonal ends 28 and 23, as shown. The ends 28- and'ZS of the side sheets are equal in length, 'and each is the same length as an off-set portion 22,23 of the bottom sheets. v I In accordance with the invention, each side sheet, as in the case of vthe fold-ing .kayak-,fis hingedly connected to a bottom sheet affording a main fold line for the craft. Preferably, two

vided for effecting the joints between .theside and bottom sheets. To this end, andas particularly illustrated in Figures '7 to 10 inclusive-of the drawings, I provide a pair of innerstr'ips '3B' which are adhesively fastened to the'inn'ersurfaces of the side and-"bottom sheets, "'attheli' l flexible, water-impervious canvas strips are proinner and outer lateral edges, respectively, and I provide a pair of outer strips 31 which are'adhesively fastened to the outer surfaces of the side and bottom sheets at their inner and outer lateral edges, respectively. As in the case of the strip I6, I similarly slit the strips 36 transversely at spaced intervals throughout their lengths, as indicated by the reference numeral 38,

to prevent accumulation of moisture that might penetrate and otherwise damage the joints.

In the folding canoe embodiment of the lpresent improvement, I likewise provide .a floor-board 39 which spreads the inner edges of the bottom sheets radially apart, as well as slightly rounds the panels atthe center of the craft and also longitudinally twists the bottom sheets from their longitudinal centers outwardly towards the ends of the craft creating a slight bowing of the sheets adjacent their longitudinal extremities. 'I'he twist effected by the pressure of the iioorboard 38 against the inner surfaces of the bottom sheets is gradual and uniform but is sufficient so that the extremities of these bottom sheets will -lie in substantially a vertical plane and will in effect constitute a continuation of the side sheet to which it is connected. Or, in .other words, the twist of the bottom sheets is such that these two sheets form both the bottom and the bow of the craft as well as bottom and stern of the craft. At the longitudinal center of the bottom sheets, the bottom sheets will :assume a definite inclination tothe horizontal when the craft is set up, and the angle of inclination assumed by the sheets will vary in accordance with the width of the sheets, as well as the width of the fioor-board. The same type of means are employed for removably disposing the floor-board in the canoe as in the case of the folding kayak, and include -a pair of strips 4I and 42 which are fastened to the inner surfaces of the bottom sheets at equal distances and on opposite sides of the inner lateral edges thereof. Likewise, these means include a series of plates 43 which are fastened in opposed -pairs to the strips 4I and 42 and which are provided with apertures 44 which, in conjunction with recesses formed in the strips 4I and 42 under plates 43, afford holes for the reception of tongues 4B carried by transversely arranged metal strips 4l and 48 fastened to the under side of the floor-board. To position the floor-board, it is only necessary to insert the tongues 46 in the holes so provided, after forcing the panels apart to some extent.

Without the use of thwarts, the craft thus far described provides a desirable racing canoe, and it is only necessary to widen the beam and maintain the same so widened by the use of thwarts to afford a canoe of general utility. Figure 7 of the drawings illustrates in plan a fold- -ing canoe of my present improvement, one-half of the view showing a general utility craft with a thwart 50 installed therein, while the other half of this view shows a racing type craft with the thwart omitted.

As in the case of the folding kayak, a pair of hoods 52 together with spray deectors 53 can be readily installed on the folding canoe, if desired. Moreover, and as shown in Figure 7 of the drawings, a exible strap 55 can be fastened across the hull adjacent the bow and stern to lend rigidity to the craft. Likewise, to facilitate folding of the craft I preferably provide metal hinges 56 at each end of the craft and, if desired these hinges can be extended, as at l, 58 to reinforce the bow and stern.

While the crafts of the present improvement can be effectively used without the use of keels, I preferably equip the folding Vcanoe with four keels 59, 6!I,`5I and 62, as particularly illustrated in Figures ,9 and 10 of the drawings. As shown, two keels 59 and 6I) are fastened to the bottom sheets adjacent to their inner lateral edges and overlying the canvas strip I I while the other keels IiI and S2 are conveniently fastened to the bottom sheets at their vouter lateral edges and overlie the canvas strip 31.

In order to enhance the rigidity of the craft, I preferably provide av series of gunwale strips for both embodiments of the present improvement, as exemplified in a folding kayak and folding canoe. These gunwale strips include a pairof relatively long strips 63 and 64 which are fastened to the outer surfaces of the'side sheets adjacent their outer lateral edges, as clearly shown in Figures 9 and 10 of the drawings. The strips 53 and 64 fall just short of the ends 23 and 253 of the side sheets I3 and I4, as depicted in Figure 8 of the drawings and, to complete the series of strips, I provide relatively short strips 65 at each end of the craft which are fastened to the outer surfaces of each bottom sheet II and I2 adjacent their outer lateral edges. These small strips 65 overlap the separated joints between the ends 28 and 29 of the side sheets I3 and I4 andthe off-set portions 22 and 23, respectively, of the bottom sheets II and I2 to provide, in effect, continuations of the gunwale strips 63 and 34. To cover the separated joints above mentioned, I provide metalplates 66 which are fastened below the gunwale strips 63, 64 and 65 at the said joints, the metal plates overlapping the joint, as clearly shown in Figure 8 of thedrawings. l

The fragmentary showing of Figure 16 ofthe drawings illustrates the nonfolding or rigid craft wherein Il provide continuous gunwale strips 5l `extending the full length of the craft and fastened to the side and bottom sheets adjacent their outer lateral edges, as shown. Metal plates similar to the plates 63 canrbe applied to the nonfolding craft-to cover the separated joint between the ends of the side sheets and the offset portions of the bottom sheets. It is to be understood, of course, that rigid or nonfolding embodiments of a kayak as well as a canoe can be constructed as shown in Figure 11.

As stated above, the thwarts 5I! and means for removably fastening the same in the hull of the craft arepreferably similar for each embodiment of the present improvement. As illustrated particularly in Figures 7 to 10 of the drawings, each thwart carries a short stud 'Il at opposite ends thereof, one stud having right hand screw threads thereon and the other stud having left hand screw threads thereon. 'I'he studs lI pass through threaded apertures in clamps 'I2 and seat in reinforcing strips I3 secured to the inner surfaces of the side sheets adjacent their outer lateral edges, as shown in Figures 9 and 10 of the' drawings. A small washer I4 is provided against which a collar 'I6 on stud 1I bears when the thwart is firmly screwed into position. This occurs at both ends of the thwarts. Upon mounting the thwarts, by turning the same in one direction of rotation, the clamps l2 at each side of the craft are tightened to firmly engage the gunwale strips 63 and Sii, the inner ends of the clamps bearingv against the ends of the thwarts. Turning of each thwart in the opposite direction of rotation loosens the clamps 'I2 and the thwarts can then be readily removed.

It is to be noted that the craft of the present improvement can be set up by use of the floorboard 39 alone, or by use of the thwarts alone, or by using both the thwarts and the floor-board. Regardless. of whether the floor-board or the thwarts are used, the bottom sheets are longitudinally twisted and outwardly bowed adjacent their longitudinal extremities in setting up the craft. Certain differences, however, are to be noted with respect to the use of door-board or thwarts, or both. If thwarts alone are used, the bottom sheets are twisted longitudinally a greater degree than when the Hoor-board alone is used and, moreover, the bottom sheets are not rounded at their longitudinal centers as is the case when the licor-board alone is used. 1f the thwarts and the floor-board are used together, there is no pressure exerted by the oor-board against the inner surfaces of the bottom sheets because of the fact that the thwarts have spread the sheets to an extent that the floor-board merely drops into position.

Particular attention is directed to the fact that the stability of all crafts constructed in accordance with the present invention is affected by the degree of curvature given to the main fold line X-X. For the greater the fold line is curved the greater will be the force applied against the outer lateral edges of the bottom sheets II and I2 by the inner lateral edges of the side sheets I3 and I4 when they are unfolded in setting up the craft, thus insuring greater rigidity and stability. The annexed drawings illustrate exemplications of highly stable kayaks and canoes embodying the present invention with theirivfold lines X-X having predetermined curvatures and with their gunwale lines arranged in predetermined relationship with respect to such main fold lines. For example, in the kayak exemplication of the present improvement, the side sheets are preferably made appreciably wide but at each end thereof are excessively reduced so as to intercept the fold line at the end of the craft. In the folding canoe exemplication, the outer lateral edges of the side sheets, which dene the gunwale line of the craft, are straight and therefore it is desirable to shape the outer lateral edges of the bot-tom sheets so as to maintain the gunwale line where it would be if the side sheets were coextensive with the length of the craft. Hence, in the folding canoe, the gunwale line at its ends is higher than the main fold line XX, as shown in'Figure 8 of the drawings. Itl may be observed that for a sailing craft exemplification, which readily can be constructed in accordance with the foregoing disclosure, it is desirable to have an excessive beam and a shallow depth to the craft. Hence, the side sheets for the sailing craft are reduced in width and the gunwale line is made straight from tip to tip of the craft, the gunwale line being defined, of course, by the outer lateral edges of the side sheets.

While I have constructed crafts embodying the present improvement from plywood, both in the folding kayak and folding canoe exemplifications, similar crafts can be constructed of any suitable metal, such as pliable galvanized iron. These metal crafts, although somewhat heavier than the plywood crafts, can be supplied with air tanks so that the crafts will float even though overturned accidentally. The air tanks conveniently can be installed in the hull fore and aft just below the hoods 52. In the metal crafts water-proof joints are provided for connecting the bottom bendable sheets at their inner lateral edges as well as for connecting cach side sheet to a bottom sheet. Y

It is to be understood that the appended claim is to be accorded a range of equivalents commensurate in scope with the advance made over the prior` art. Y

I claim: f

A marine craft comprising a hull including a pair of bendable normally fiat bottom sheets and a pairof bendable normally at side sheets, each of said bottomV sheets having an inner lateral edge which is curved at its longitudinal extremities and substantially straight betweenthese curved portions, and havingY an outer lateral edge curved throughout with a curvature reverse to the curvatures of` said inner edge, and each of said side sheets having curved inner and straight outer lateral edges, hinge means joining inner lateral edges of said bottom sheets along a longitudinal medial line of thecraft, hinge means joining each side sheetY to a bottom sheet at their innerand outer lateral edges respectively,V and Aremovable means positioned in said hull bearing. against opposite sheets on each Side of the medial line, said removable means being of an extent to twist said bottom sheets and forcesaid opposite sheets apart such a distance that a longitudinal extremity of each bottom sheet lies in substantially the same plane as the adjacent extremity of a connected side sheet at that end of the craft.

CHARLES HASKELL CLARK.

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