Патент USA US2120332код для вставки
June 14, 1938. F_ H, JACKSON PACK BOAT - Filed June 8, 19556 7 2,120,332 , 5- Sheets-Sheat 1 ATTO RN EYS June 14, 1938. F. H. JACKSON 2,120,332 PACK BOAT Filed June 8, 1936 3 Sheets-Sheet 2 ATTO RN EYS June 14, 1938. _ F_ H, JACKSON 2,120,332‘ PACK BOAT Filed June ‘a, 1936 ' f I 1 2'2 l W,‘ H V $28 / s Sheets-Sheet 5 23 r . Q8 no.5 ' L9‘ L‘ ' / 6 7 /4L3 I as - 2e 57 2'; 9-8 2o ATTORNEY6 Patented June 14, 1938 ' 2,120,332 UNITED STATES PATENT orrice 2,120,332 PACK BOAT Fred H. Jackson, Ilion, N. Y., assignor of one half to George S. Jackson, Ilion, N. Y. Application June 8, 1936, Serial No. 84,065 2 Claims. My present invention relates to pack boats meaning thereby folding, collapsible and knock down boats that are of such construction and of such light weight that they may be readily '5 carried in a camper’s pack. The purpose of this invention is to provide a pack boat of new and improved construction and particularly one where the parts are so‘ con structed'and of such light weight that the parts 0 may be readily carried in a camper’s pack by even one man. Heretofore most collapsible or folding boats have included constructions or» ‘parts that make the boat awkward to pack and carry and too heavy for the ordinary man to '15 carry with comfort. Further purposes of this invention are to pro vide an article of the type mentioned which has its parts of such form, size, weight and combina tion that the parts can be readily placed in one ‘270 or two compact relatively light packages for carrying in a camper’s pack or in an automo bile; to have the parts of such new and im proved construction that they may be readily and very quickly assembled by the ordinary per =25 son and without the use of any tools and yet pro— vide a boat that is strong, rigid, durable and readily able to carry three men and similarly to have the construction and combination of parts such that the boat may be'as readily taken apart '30 by any one without the use of tools in a very short time and packed into one or more com pact packages ready for carrying or storing, to provide a new and improved form of keel for a pack boat that is made in sections, but readily 35 assembled to be extremely strong and rigid and not liable to break or be strained even under hard usage and to have ‘the keel of such form as to combine with the other parts of my pack boat in a' specially convenient and effective man 40 ner and further to provide a pack boat having a new type of ribs in the form of half ribs, the parts of each pair of which are separate for ‘making and packing, but are assembled together to form a rib for mounting upon the keel and 45 combining with the rest of the boat, to provide in such a pack boat a complete gunwale formed of a plurality 'of sections permanently pivoted together and adapted to be folded into very com pact form for carrying and storage but adapted '50 to be readily unfolded and mounted upon the upper ends of the ribs and the bow and stem pieces of the boat without the use of tools and without the use of any separate fastening members. 55 ~ Fig. lis a plan view of the frame, that is the (o1. 9-2) keeL'the ribs, the bow and stern pieces and the gunwale of a pack boat embodying my invention. Fig. 2 is a side elevation of the frame shown in Fig. 1. ' _ Fig. 3 is a transverse sectional view on a some- 5 what enlarged scale on line 3-—3 of Fig. 1 but showing the canvas shell in place. Fig. ll is a cabinet projection of one of the intermediate keel sections. ' Fig. 5 is a longitudinalcentral section through ' 10 the intermediate keel section shown in Fig. 4 and Fig. 6 is a similar section showing two keel splines in place upon the said intermediate sec tion of the keel and with the metallic reinforc ingv cross pieces in place upon the keel section. 15 Fig. 7 isan isometric projection of one of the ‘ _ keel splines. Fig. 8 is'a cabinet projection of an end section of the keel with'a bow or stern piece assembled therewith. ’ 20 Fig. 9 is a central longitudinal section through the end section of the keel shown in Fig. 8. Fig. 10 is a plan view of the gunwale in partly folded condition. ‘ Fig. 11_ is an isometric projection of the inner 25 end of a metallic half rib provided with the pair of dowel pins used to connect the two halves of a rib. Fig. 12 is an isometric projection of the inner portion of the complementary or mortised half 30 of a metallic rib. Fig. 13 is a similar View when the inner ends of these half ribs are assembled and connected by the dowel pins. Fig. 14 is a view similar to Fig. 13 showing the 35 inner ends of these, half ribs inserted in place upon the keel but with the locking clip still open. Fig. 15 is an isometric projection of the inner ends of a pair of half ribs when the halves are placed side ‘by side throughout their length for 40 the purpose of packing. } _ Figures 16 and 17 are transverse sections of the gunwale and cover. Referring to the drawings in a more particu lar description it will be seen that a pack boat 45 embodying this invention comprises a keel formed of several separate sections adapted to be at tached end to end, a bow piece and a stern piece projecting respectively from the forward and rear keel section and then extending upwardly 50 to form the bow and stern posts respectively,‘ a plurality of ribs preferably in the form of pairs of half ribs projecting laterally from the keel and turned up in the properform to givethe desired ‘shape to the boat and a gunwale formed 55 2,120,332 2 of a plurality of sections permanently hinged together and attached to the upper ends of the bow and stem posts and the upper ends of the half ribs. Upon this frame is removably secured a shell preferably formed of strong durable fabric or ?brous material such as canvas. The keel is composed of a plurality of separate detachable sections, each preferably formed of wood and adapted to be placed ‘end to end with 10 the sections of the keel held in alignment by a set of strong light metallic splines 20. See Fig. 'I. tion against strain placed upon the spline or upon the wooden section. Preferably the lower re inforcing strips 25 are let into the wood at the bottom the full thickness or height of the said strips so as to have the bottom face of the keel sections ?at and free from the projections so as not to cause any local wear below the keel upon the canvas shell 29. It will now be seen thatthe lower reinforcing strips‘25 close the bottom of the spline recesses 10 24 and that the tops of these reinforcing strips Preferably these splines will be formed of straight pieces of strong aluminum, preferably rectangular in cross section. 15 I have found that splines made out of rolled aluminum one-half inch wide and one high is su?iciently strong and rigid for the pose for an ordinary convenient sized pack adapted to carry two or three men. cold inch pur boat For a boat 20 of the size suggested there will be a front keel section 2|, a rear keel section 22 and. ordinarily two intermediate keel sections 23--23. Obviously the number of intermediate keel sections may be varied to produce a larger or smaller boat or 25 ‘to produce a boat where the'keel sections may be 25 are engaged directly by the bottom edge of the half of the spline coming into recess 24. The cen tral longitudinal sectional view, Fig. 5, shows the location and general proportion of these recesses 15 24 at the opposite ends of the intermediate keel sections. In Fig.4 a similar view of one of these intermediate keel sections is shown but with the lower re-inforcing strips 25 and the upper re inforcing strips 28 in place and with a spline 20 20 shown inplace in both ends of the keel section. It will be un-derstoodthat the recess 24 as closed keel sections are more in number as by having at the bottom by strips 25 will readily but closely receive half of a spline 20 by inserting the spline endwise through the open end of the recess 24 25 and-sliding it inwardly of the recess. It will be noted that with the recesses 24 centrally dis posed in the several intermediate sections and in more than two intermediate sections, but with the sections including the front and rear keel sections shorter. I found from experience, how sections 2| and 22, the recesses of adjoining pairs of keel sections will be in alignment to re less in number but proportionately longer than herein suggested or to produce, a keel where the ever, that a boat having two intermediate sec tions is satisfactory as it combines a minimum number of sections and joints for the keel with 35 a convenient length of the keel sections for pack ing the parts of the boat into compact bundles. As will be seen from Fig. 4 which is a cabinet projection of one of the intermediatekeel sec-' tions 23, these sections are preferably rectangular 40 in cross section so as to be readily and easily formed out of wood with a minimum of work. Into the opposite end of each of the intermediate keel sections there is provided a longitudinally extending recess 24 projecting into the section 45 from the end and from the bottom face of the section. These recesses are placed or made tov be in the center of the section measured crosswise thereof. As this boat is illustrated and assuming the splines to be of the cross sectional size above 50 indicated, the recesses 24 will be one-half inch in width to closely receive and hold one half of a spline 20. The length of each recess 24 will be half the length of the spline: 20. As shown in the drawings, the recess 24 will be slightly higher 55 measured from the bottom of the keel section than the one inch height of the spline 20. This is for the purpose of allowing at least a spaced pair of strong metallic re-inforcing strips 25 to be let into notches26and 21 extending prefer ably the full width of the bottom of the keel the adjoining ends of the front and rear keel solve the straight spline and hold adjacent pairs of keel sections also in proper straight alignment. In Fig. 8 there is shown a cabinet projection of an end section of the keel. For deflniteness this view is numbered to show. the front section’ 2! of the keel, but the rear section is of similar construction and so does'not need to be separately illustrated nor described. At the inner end of this end keel section there is provided a spline recess'3l) projecting in from the extremity of this section for the length of half of a spline 20 and extending up from the bottom of the keel section and closed by a pair of bottom re-inforcing strips 25 as already described in detail with regard to the intermediate sections of the keel. Preferably also. there is let into the wood of the end section 'a top reinforcing strip 28 connected by long through bolts or rivets to the corresponding re inforcing strip 25 nearest this end of the keel section. In other words, the inner ends of both the front and rear keel sections are constructed similar to the two ends of the intermediate sec tions of the keel and are adapted to receive one half of the spline, the other end of which is ultimately housed in a recess 24 of an intermedi ate section. It will thus be seen that the four or more sections of the keel are assembled by in serting half of a spline in one section and the other half of the spline in an aligned section pieces. These re-inforcing strips are strongly ' of the keel and drawing the said pair of sections secured to the Wood of the section as by long together. The splines ?t the recesses abovethe screws extending vertically of the sections or by reinforcing strips 25 easily enough to allow the through bolts or rivets extending through the 65 opposite ends of these reinforcing strips and then through the Whole height of the keel section. Preferably in order to make a still stronger con struction near the extreme end of the keel section there is provided a top reinforcing strip 28 let into a notch in the upper face of the keel section opposite the end bottom notch 21. The through bolts or rivets for the end lower strip‘25 then preferably pass through the upper reinforcing strip 28 so as to give to the structure .the full 75 strength of all of the wood at the end of the set: keel to be assembled without undue labor and entirely without the use of tools or implements. On the other hand, the splines ?t into the sec tions closely enough to hold the pairs of sections closely and rigidly in proper alignment and tightly enough to keep the four or more sections of the keel all together while the ribs are being 70 placed thereon and while the bow and stem pieces are being placed in position and until the sectional gunwale has been mounted upon the frame so provided. The gunwale in connection With'the half ribs and the bow and stern pieces 17-5 2,120,332 forms the ultimate and positive locking means to hold the sections of the keel from any possible endwise dislocation. It will be seen that I have provided no locking means adjacent the keel and keel sections and splines for holding these parts together against endwise dislocation and I have found that the gunwale in combination with the other parts of the frame forms an adequate and sure locking means for the keel sections. 10 The bow piece 30 and the stern piece 3| are preferably substantially alike in that they are formed of metal preferably and conveniently cold rolled aluminum one-half inch square in cross section of the proper length to be bent or shaped 15 so as to form upon the bow piece a horizontal part 32 and a bow post proper 33 while the stern piece 3| has the horizontal part 34 and the rear or stern post 35. The suggestion here made as to the size of the metal is simple illustrative as in 20 dicating a size and grade of metal strong enough for the purpose. As is best shown in Figs. 8 and 9, the forward part of the front keel section 2| is provided with a longitudinally extending recess 36 extending 25 from the front end of this keel section rearwardly a su?icient distance to house about the rearward half of the horizontal part 32 of the bow piece 36. This recess 36 in general construction is like the recesses 24 in the intermediate sections and 30 the recess 36 in the rear end of the front keel section 2| except that the recess 36 is of lesser height to closely receive the horizontal part 32 of the bow piece. This recess is closed at the bot tom by front and back crosswise extending rein 35 forcing metal strips 31 and 38 let into the bottom :of the said keel section so as to be ?ush with the bottom of the keel section and so that their upper faces will directly support the bottom of the hori zontal part 32. Preferably a front upper reinforc 40 ing piece 39 is let into‘ the upper side of the forward extremity of the front keel section 2| about as shown in Fig. 8 directly over the front reinforcing piece 37. Through rivets 40 per manently connect the reinforcing strip 31 at the 45 bottom and the top reinforcing strip 38 and pass through the intermediate wood of the sec tion. The slot 36 is formed in the central portion of the keel and extends accurately longitudinally thereof so that the projecting portion of the part 32 and the stem 38 of the bow piece are held ac curately in alignment with the longitudinal axis of the keel. The bow piece is inserted in its recess 36 in an obvious manner by inserting the rear portion of the horizontal part 32 into the forward part of the recess 36 and pushing the metal piece to the rear. A similar recess 4! in the rear end of the stern keel section 22 receives in a similar manner the forward portion of the horizontal part 34 of the stern piece 3|. The rear end of the stern keel section 22 is reinforced by a top reinforcing piece and a pair of bottom reinforcing pieces which bottom reinforcing pieces engage and support the bottom surface of the part of the stern piece ?t ting into said recess 4|. The upper ends of the bow post 33 and the stern post 35 are provided with suitable means for mounting thereon the bow and stern respectively of the sectional gunwale. Such mounting means conveniently consist of an L-shaped bracket 42 most plainly shown in Fig. 8 permanently se cured at its lower end to the post and affording an upwardly opening slot 43 on the forward side of the bow post and the rearward side of the 75 stern post. 3 The ribs are of metal preferably cold rolled aluminum and conveniently of the size of one half inch square in cross section. The ribs are formed of pairs of halfribs 44 and 45 respective— ly. The half ribs of each pair are similarly shaped as to length and curve according to the .5 position in the boat that any pair of ribs is to occupy. The pairs of half ribs 44 and 45 ‘overlap each other at the keel a little more than the. width of the keel as appears best in Figs. 1, 3 and 14. Each half rib 44 is provided at its inner or 10 keel end with a pair of metal pins 46 extending horizontally crosswise through the said. half rib and with their ends’ projecting beyond the metal of the half rib at the same side thereof as shown 15 in Fig. 11. The inner or keel end of the comple mentary half rib 45 is provided with a pair of correspondingly located and shaped holes 41 adapted to easily and closely but detachably re ceive the projecting pins 46. Pins 46 are of a 20 length not only to go‘ through the holes 4'! in the half rib 45 but to project therebeyond a short distance when the half ribs of a pair are as sembled as appears inrFigs. 13 and 14. The pins 46 and holes 41 it will be understood are so lo 25 cated as to hold the overlapping parts of the two half ribs securely in alignment when the two half ribs are assembled“ At the points in the keel where the ribs are to be mounted thereon the upper part of the several wooden keel sections 30 are provided with crosswise notches 48 of a depth corresponding to the height of the ribs and of a width equalling the width of the two overlapping parts of the half ribs. Assuming as above sug gested that the ribs are formed of metal one 35 half inch square, then these notches 48 will be one-half an inch deep and one inch wide. The overlapped portions of a pair of half ribs when placed in their proper recess 48 in the keel will be held securely but removably therein against any 40~ twisting or swinging in a horizontal manner. Each pair of half ribs will be locked in place in its notch 48 by a button 49 pivotally mounted on the top of the keel adjacent the notch by means of a headed screw 50 or the equivalent there of. In Figs. 4 and 14 these buttons are shown 45. in open position. By swinging the buttons way around from the position shown they come over the overlapped part of the half and securely hold said rib from movement ward relative to the keel. half will ribs up ‘ 50 The pair of pins 46 on each rib are spaced apart slightly more than the width of the keel so that when each rib is mounted upon the keel and seated in its notch 48 the pins 46 will be close to the opposite vertical sides of the adjacent 65 portion of the keel. These projecting pins there fore formthe ready means for properly locating the ribs upon the keel when the ribs are put in place and when the ribs are once mounted the pins prevent the ribs from moving crosswise of 60 the keel. ' ' The primary purpose of making the ribs in the form of half ribs 44 and 45 is for convenience in packing the parts of the boat into compact small bundles convenient to be carried or stored. 65 The ribs near the middle of a boat of this sort are bow-shaped as will be seen by the Widest ribs shown in Fig. 3; Farther to the bow or stem the ribs decrease in extent from free end to free 70 end as the boat decreases in Width. It will be seen, therefore, that in a boat of the sort herein illustrated there will be at least four different patterns of complete ribs and that these shapes are not adapted to nest closely together nor to 2,120,332 lie compact ‘against other parts of the boat. Furthermore, the, distance between the free ends of a rib especially the ribs at the middle of the boat may be about forty inches ‘which is too long to make a convenient package for a man to carry in a pack. The bow-shaped form of the neces sary ribs and the variance in the form of the different ribs further make the'parts unadapted to be nested closely together or to form a con ll) venient size or shape of a package of parts to be carried either together or especially in conjunc tion'with other parts of the boat. Accordingly I have formed the ribs of this boat'as-half ribs with the parts of each rib adapted to be readily assembled .when the boat is to be set up. By forming the ribs in such half ribs the over—all length of 'the parts for packing is reduced by about half the length. The sixteen parts of an eight ~rib boat can then be much more con 20 veniently placed together and carried in contact with other parts. The large number of these separate‘parts, however, is reduced because when the boat is taken apart the half ribs of a pair are ?rst taken apart from their extended use-d position and are mounted upon each other in re versed position, but with the curved parts of the two halves of a rib aligning with or next to each other and held in this aligned position by the pins 46 again being placed through the holes 4'! as 30 appears in Fig. 15. Accordingly in an eight-rib boat there will be eight packages of parts, each pair of 'half ribs'conveniently held together by the pins 46. The eight pairs commonly of four different ‘sizes and shapes as suggested in Fig. 3 may then be conveniently nested into a fairly compact package of convenient length and of not such excessive curvature as to prevent placing these pairs together into a compact bundle. For a boat of about the size and capacity herein illustrated and described, eight ribs are ample to hold the canvas shell 29 properly ex tended and out in the desired shape. This allows two ribs to be mounted upon each keel section which is a convenient arrangement in that it al lows the proper spacing of the ribs and provides for the mounting of the ribs upon the keel sec tions'at convenient distances from the ends of the keel sections. The gunwale 5! is composed of an angular shaped bow piece 52, an angular shaped stern ill) piece 53 and two sets of gunwale sections 54. These parts are permanently but pivotally con nected as by copper rivets 55 connecting the ad jacent ends of the gunwale sections of each se— ries and by sirnilar rivets 5% connecting the front section of each series to the bow piece 52 and similar rivets 5'! connecting the rear end of the rear gunwale sections to the stern piece 53. The pieces forming the sections of the gunwale are of 60 metal preferably aluminum strips for which pur pose-I ?nd strips one-inch wide and one-eighth inch thick are suf?ciently strong and rigid and light enough for the purpose. The end pieces 52 and 53 of the gunwale will be formed of similar aluminum strips of about 65 the same size and weight or if desired slightly heavier material. Each of these pieces will have a central part 52' and 53’ adapted to be slipped down into the open slot 43 at the top of the bow and stern posts respectively. The end of the 70 pieces 52 and 53 will slant outwardly as they project toward the other end of the boat so as to align more or less closely with the adjacent end of the end sections upon the opposite sides of the boat. Convenient means are provided at theupper free ends of the half ribs to detach ablyreceive the gunwale sections. Such means conveniently consist of‘ an upwardly opening slot formed in the upper ends of the ribs of a width to readily but closely receive the gunwale. As suming that the keel has been assembled as al ready outlined and the bow and stern pieces and the ribs assembled thereon, the gunwale will be assembled upon the upper ends of the bow and stern pieces‘ and the ribs by ?rst placing one end 10 piece. as 52- of the gunwale in the slot 43 of the bow post.‘ Then with the gunwale unfolded its successive sections will be placed in the slots pro vided in the several ribs and then the stern piece .15 53 mounted at the top of the stern post. One-preferred form of construction or com bination of parts of my boat is clearly shown in Figs. 1' and 2 and consists in having each of the gunwale sections except the end sections thereof engaged by and supported in the upper ends of 1 two half ribs. In other words, it will be seen that these intermediate sections of the gunwale are supported at two well-spaced points by the half ribs of adjacent ribs. Assuming that the boat is constructed as herein illustrated by using eight _ ribs, the gunwale on each side of the boat will have four intermediate sections. This spaced supporting of a gunwale section by at least two “half ribs tends to rigidity when the framework is up‘ by very largely reducing any tendency . of these sections to pivot or swing upon the ribs. Obviously any downward pressure upon an inter mediate section of the gunwale between its two supporting ribs will simply seat the gunwale more strongly in the ribs. Any possibility of the gun- , wale so swinging or its adjacent sections folding is entirely obviated when the canvas shell 29 has been mounted upon the framework of the boat because the said shell is so shaped and is of a size that when its opposite sides or edges are se cured to the opposite series of gunwale sections a very considerable tension is placed upon the canvas‘ shell ‘to keep the shell taut and this ten sion operates to produce a downward pull upon 'all of the sections of the gunwale which is thereby 45 e?ectively locked from disengagement of any of its parts from the upper ends of the ribs. It ‘will be understood, furthermore, that the length of the complete gunwale relative to the up per end of the bow piece 30, the upper end of the stern piece 3| and the upper ends of the several half ribs“ and 45 will be such as to place a considerable inward endwise draw or tension upon the bow and stern pieces and some inward tension upon the several half ribs. The con 65 siderable endwise tension placed upon the bow and stem pieces operate not only to hold the horizontal parts 32 and 34 of said end pieces securely‘ in their respective recesses in the end keel sections, but also operates to hold all of the 60 keel sections from any possible longitudinal dis placement relative to each‘ other. In other words, the gunwale is the positive means for locking the several sections of the keel together and for locking the bow and stern pieces to the 65 keel. The slight inward draw of the gunwale ‘upon the upper ends of the ribs operates to hold .each of the intermediate gunwale sections snugly in the ribs and to stretch out any endwise play or looseness between the pivotally connected sec 70 tions of thergunwale. The-fabric shell 29 is conveniently formed of relatively heavy strong, durable canvas suitably ?lled and coated to be water-tight and leak proof and durable. at 2,120,332 I prefer to make this canvas shell 29 of one integral piece of canvas of such length as to extend the whole length of the boat and of a width greater than the outside outline of the ribs so that there will be an appreciable hem or overlapping portion outside the gunwale of the boat. Preferably the piece of canvas is longer than the boat and its end parts are overlapped or pleated at the bow and stem and secured to 10 gether thus avoiding the cutting of the material and also providing considerable re-inforcement. Convenient means are provided for readily at taching the gunwale edges of the canvas shell to the opposite sides of the gunwale. These at 15 taching means also are such as to allow for plac ing the whole canvas shell under desired tension. To accomplish both of these purposes I provide on one edge of the canvas shell of the boat a series of hooks 58. See Fig. 16. Each of these 20 hooks is preferably made from a narrow strip of metal inserted in a suitable grommet 59 placed in the hemmed edge of the cloth and then having the two halves of the strip‘ bent towards each other in line with the fabric and then together 25 bent over to form an open bottomed hook that can be readily placed over the gunwale as ap pears in Fig. 16. The proper number of these hooks 58 will be placed all along one edge of the shell and when the shell is to be placed upon 30 the boat these hooks will be ?rst placed over the gunwale on that side of the boat. The shell will then be stretched towards the other side of the boat and that edge of the shell will be stretched up to the gunwale on that side of the 35 boat with a proper tension and securely but de tachably fastened thereto by means of one or more cords 60 run through grommets 6| on that side of the casing near its edge. Between or near the grommets 6| the cord 60 40 is run through or tied to eyes 62 provided pref erably on the inside face of the half ribs near, their upper end as appears in Figs. 3 and. 17. In Fig. 3 the near end of the cord 60 is shown not yet run through several of the nearer eyes 62. 45 What I claim as new and desire to secure by Letters Patent is: 1. In a pack boat construction the combina tion of a plurality of foldable ribs, each rib com posed of two bent, metal half-ribs shaped to have 5 their keel ends detachably placed side by side in overlapping relation and their gunwale ends pro jecting away from each other and forming when so assembled a complete rib, the half-ribs of each rib having in their overlapping keel ends a pair of spaced cooperating ?xed permanently mounted metal projections and laterally arranged sockets . to detachably receive the same whereby a rigid whole rib is formed by assembling the two half ribs sidewise in such extended position, a keel 10 having in its top, laterally extending rib-receiv ing spaced slots, each the width of the combined overlapping keel portions of a rib, the opposite walls of said slots holding together the half ribs of each rib, a gunwale detachably connect ing the upper ends of the ribs and a ?exible cas 15 ing stretched beneath and around said keel, gun wale and ribs, the tension of said casing holding the ribs down in the keel and'so keeping the ribs extended. 20 2. In a pack boat construction the combina tion of a plurality of foldable ribs, each rib com posed of two bent, metal half-ribs shaped to have their keel ends detachably placed side by side in overlapping relation and their gunwale ends pro 25 jecting away from each other and forming when so assembled a complete rib, the half-ribs of each rib having in their overlapping keel ends a pair of spaced cooperating ?xed permanently mounted metal projections and laterally arranged sockets 30 to detachably receive the same whereby a rigid whole rib is formed by assembling the two half ribs sidewise in such' extended position, a keel having in its top, laterally extending rib-receiving spaced slots, each the width of the combined 35 overlapping keel portions of a rib, the opposite walls of said slots holding together the half ribs of each rib, a gunwale detachably connecting the upper ends of the ribs and a ?exible casing stretched beneath and around said keel, gunwale 40 and ribs, the tension of said casing holding the ribs down in the keel and so keeping the ribs l extended, the said projections on said rib sections extending beyond the overlapped parts of said sections close to the opposite sides of the keel and serving to hold the several complete two-part ribs from movement laterally of the keel. FRED H. JACKSON.