Patent Publication Number: US-6983715-B2

Title: Inflatable boat having a detachable rigid hull

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to French Patent Application No. 03 05554 filed on May 7, 2003, the entire contents of which are hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of inflatable boats having rigid hulls, and it relates more specifically to improvements made to those of such rigid-hulled inflatable boats in which the hull is made up of a plurality of segments facilitating stowage and transport of such boats. 
     BACKGROUND OF THE INVENTION 
     Document FR-A-2 765 855 describes an inflatable boat of the type in question and which comprises:
         two side buoyancy tubes;   a floor that is rigid at least transversely and that is interposed between said tubes:   a flexible bottom sheet that covers the underside of the rigid floor and that is secured in watertight manner to said tubes; and   a hull of approximately V-shaped cross-section disposed under the flexible bottom sheet, which hull comprises at least a central longitudinal strip in the shape of a V-shaped trough that is rigid, and that is made up of a plurality of longitudinal segments assembled together end-to-end, and secured together by releasable fixing means.       

     With reference firstly to  FIGS. 1 and 2  of the accompanying drawings (which are reproductions respectively of  FIGS. 4 and 9  of Document FR 2 765 855), it is recalled briefly that the inflatable boat, given overall numerical reference  1 , has respective floats in the form of inflatable tubes  2  on each of its sides. The two tubes can be joined at the bow to give an overall U-shape that is open at the stern of the boat. The two buoyancy tubes  2  are interconnected at the stern by a transom (not shown in  FIGS. 1 and 2 ) and at their bottoms via a floor  3  that is rigid, at least transversely. 
     A flexible bottom sheet  16  extends under the rigid floor  3  and covers the underside of the rigid floor  3 , being secured in watertight manner to the two buoyancy tubes  2  and to the aft end of the rigid floor or to the transom. 
     Under the flexible bottom sheet  16 , a hull  4  is situated that is approximately V-shaped in cross-section. The hull  4  comprises at least a central longitudinal strip  6  in the form of a V-shaped trough which is rigid and which is made up of a plurality of longitudinal segments assembled together end-to-end, and secured together by releasable fixing means. 
     In the example shown in  FIG. 1 , the rigid strip  6  occupies only the central portion of the hull  4 , and the two portions of the hull that are situated on either side of the rigid strip  6  are made up of flexible strips  7  made of a material of the same type as the material of the flexible bottom sheet  16 . Releasable fixing means  8  (e.g. and advantageously a rod engaged in a groove) secure the flexible strips  7  detachably to the rigid central strip  6 , while, via their outermost longitudinal edges, the flexible strips  7  are secured at  13  to the flexible bottom sheet  16 , as shown in  FIG. 1  (or even to the buoyancy tubes  2  in the examples of  FIGS. 1 to 3  in Document FR 2 765 855). 
     In the specific example shown in  FIG. 1 , the rigid floor  3  has a particular make-up since it is made up of a plurality of panels  9  (e.g. from two panels to four panels depending on the length of the boat, and typically three panels for a medium-sized boat) which are rigid (e.g. made of metal, in particular of aluminum or of aluminum alloy). In addition, each floor panel  9  has edges raised at an angle such that said edges lie approximately in alignment with the sides of the underlying hull. 
     In the configuration shown in  FIG. 1 , the flexible strips  7  are secured to the flexible bottom sheet  16  approximately along the folds  13  of the raised edges of the floor panels  9 . In other words, the flexible bottom sheet  16  is provided on its bottom face with longitudinal flaps  7  that can be secured to the rigid central strip  6 . 
     In order to hold the resulting assembly under tension, a spacer  5 , advantageously of the pneumatically inflatable type, is interposed between the assembly comprising the rigid floor  3  and the flexible, bottom sheet  16 , and the rigid central strip  6 , as shown in  FIG. 1 . 
     In another example shown in  FIG. 2 , the hull  4  is constituted entirely and only by the central rigid strip  6  which is removably secured directly to the flexible bottom sheet  16  by means  8  as mentioned above, approximately along the folds  13  of the raised edges of the floor panels  9 . A boat configured in this way is simpler to manufacture (flexible flaps  9  omitted) and easier to assemble (the fixing rod, which is, in this example, secured to or integral with the flexible bottom sheet  16 , is tensioned better and is easier to engage into the groove provided in the edge of the central strip  6 ). 
     Document FR 2 765 855 gives the overall provisions for such boats, but it does not give any specific technical solution as regards assembly and structure of the component segments of the rigid central strip  6  of the hull  4 . However, the rigidity of the hull, and therefore the rigidity of the central strip  6 , which constitutes the working portion of said hull, is essential for guaranteeing that the boat has the required qualities (stability, and course-holding). 
     In addition, it should be emphasized that the whole purpose of boats of this type is to be capable of being assembled and disassembled as easily as possible, or even, for certain users, of being assembled and disassembled as quickly as possible and in difficult conditions (e.g. in the dark). 
     OBJECTS AND SUMMARY OF THE INVENTION 
     An object of the invention is thus to provide an original technical solution for assembling together the rigid segments of the hull, which solution is capable of satisfying the very demanding requirements of certain users. 
     To these ends, when an inflatable boat as mentioned in the preamble is organized in accordance with the invention, said releasable fixing means for releasably fixing together two consecutive hull segments comprise:
         at each side top end, at least one longitudinally-extending projecting finger on an end of one segment and at least one respective facing longitudinal recess provided in the abutting end of the adjacent segment and suitable for receiving said projecting finger; and   in the tip portion of the V-shape and inside the hull, at least one connection member on an end of one segment, and at least one corresponding connection member situated inside the adjacent segment, and a retaining pin suitable for being engaged through the connection members.       

     Thus, by the means provided in accordance with the invention, the two fingers provided at the top and engaged in facing recesses in adjacent segments perform both a guide function for ensuring that the two rigid segments of the hull are mutually positioned correctly while they are being assembled together, and a retaining function for mutually retaining the two segments once they are assembled together end-to-end. 
     In order to prevent the two segments as assembled together in this way from coming apart, it is then much simpler, rather than providing locking at said fingers engaged in the recesses, to implement locking means in the tip of the V-shape, both for preventing the two segments from coming apart in their bottom zone and because sufficient space is available there to locate means of very simple design (a pin engaged through connection members). 
     It should be noted that the means implemented for reliably assembling together two rigid hull segments are extremely simple, are inexpensive because of their structural simplicity, and, above all, do not require any tools for being implemented. Finally, this simplicity makes it possible for assembly to be performed under difficult conditions. 
     In order to facilitate inserting and removing the pin for securing together and releasing the retaining connection members, it is advantageous for one of the segments to be provided with an opening near the connection member, which opening is provided with a hatch that can be opened and closed from the outside. Here too, the presence of the hatch considerably simplifies and thus accelerates inserting and removing the pin. 
     Advantageously, at least when the structure of the boat so permits, it is desirable for a substantially triangular respective transverse plate to be provided at each end of each of the intermediate and stern segments, and at the aft end of the bow segment. These plates make it possible to strengthen the rigid hull segments. In order to avoid an undesirable increase in weight, it is possible for each plate to be perforated. 
     In order for the hull to have the desired rigidity while the boat is being used, it is possible for the hull segments to be made of a lightweight metal such as aluminum or an aluminum alloy so as to be as light in weight as possible, thereby facilitating transporting the boat as disassembled and folded up. It is also possible to consider making the hull segments of a composite material that has suitable weight and strength characteristics. 
     Also with a view to obtaining a hull structure that is as rigid as possible when in use, and also to assembling reliably the rigid segments to the flexible bottom sheet or to the flaps secured thereto, provision is made for each longitudinal edge of each hull segment to be provided with two mutually-parallel grooves suitable for receiving a pair of rods or of fixing bolt ropes secured to or integral with said flexible bottom sheet. 
     A preferred embodiment of the invention, which is applicable to the boat shown in  FIG. 2  of the accompanying drawings, consists in that the rigid floor is made up of a plurality of segments assembled together end-to-end in detachable manner, each floor segment having side edges that are raised so that the floor segment has a cross-section which is approximately V-shaped with a truncated tip, and in which the inclination of the branches is approximately the same as the inclination of the branches of the V-shape formed by each hull segment;
         in that the flexible bottom sheet fits snugly over the rigid floor, with its pairs of bolt ropes extending substantially along the two longitudinal folds formed by the raised edges of the rigid floor; and in that the rigid hull mounted on said pairs of bolt ropes extends, downwards, approximately in alignment with the raised edges of the rigid floor.       

     In order to improve the securing of the rigid segments to the flexible bottom sheet or to the flaps secured thereto, it is advantageously possible to make provision for the flexible bottom sheet to be provided, at its forward end, with a flap suitable for being folded and strapped over the forward end of the bow segment of the rigid hull, and for retaining means, in particular having straps, to be provided at the aft end of the stern segment, for locking the rigid hull longitudinally. 
     In the most common embodiments, the central rigid strip of the hull may advantageously be constituted by two to four segments, typically three segments for a medium-sized boat, it being possible for this number of rigid hull segments to match the number of rigid floor segments in the embodiment of the boat shown in  FIG. 2 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood on reading the following detailed description of certain particular embodiments which are given merely by way of non-limiting example. In the description, reference is made to the drawings, in which: 
         FIGS. 1 and 2  are diagrammatic cross-section views of two examples of inflatable boats to which the invention applies; 
         FIG. 3  is a fragmentary perspective view showing how the ends of two mutually adjacent hull segments are shaped with a view to them being assembled together in accordance with the invention; 
         FIG. 4  is a fragmentary perspective view showing the two ends of the mutually adjacent hull segments of  FIG. 3  after they have been assembled together; 
         FIG. 5  is a highly simplified longitudinal vertical section view of the configuration of  FIG. 4 ; 
         FIG. 6  is a view from underneath of an inflatable boat of the type shown in  FIG. 2 , configured in accordance with the invention; and 
         FIG. 7  is a perspective view looking towards the stern, showing the inside of the boat of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description, given with reference to  FIGS. 3 to 5 , refers more specifically to equipment for a boat having the structure shown in  FIG. 2 , this embodiment currently appearing to satisfy as well as possible the requirements of practical use. However, it is understood that the provisions explained above are entirely transposable, ignoring the dimensions and in particular ignoring the width of the rigid hull segments, to the embodiment of the boat of  FIG. 1 . 
     With reference firstly to  FIG. 3 , the ends of two rigid hull segments  11  suitable for being assembled together end-to-end are shown in perspective. 
     Each rigid segment  11  is made of a metal, and preferably of a lightweight metal (e.g. aluminum or aluminum alloy) or of a composite material, and it is formed of two walls  17  disposed in a V-shaped configuration so that the cross-section is V-shaped, as explained above. 
     At each side top end of the ends of one of the segments  11  (the left segment in  FIG. 3 ), at least one projecting finger  18  is provided that extends longitudinally, and, at least one respective longitudinal recess  19  is provided in register in the other segment  11  (the right segment in  FIG. 3 ). 
     Naturally, it is possible for the fingers  18  and the recesses  19  to be located in any configuration, i.e. both fingers  18  can be situated on the same segment  11  and both recesses  19  can be situated on the other segment  11 , or else each segment end  11  can be provided with a finger  18  on one side and with a recess  19  on the other. 
     The fingers  18  may be of sufficient dimensions, e.g. of sufficient length to penetrate deeply into the respective recesses  19 , and to withstand the shear forces. 
     This finger/recess configuration is not only suitable for mutually supporting the two abutting ends of the adjacent segments, but also for facilitating assembly of the two segments by procuring guiding which ensures that the two segments are mutually aligned. 
     In order to lock the assembling-together of the two ends of the segments  11 , it is admittedly possible to act on the fingers  18 , e.g. with snap-fastening means. However, such means are complex and fragile and they do not procure the desired strength and reliability. 
     Locking means are therefore provided at the tip of the V-shape and inside the rigid segments  11 , in the form of two perforated connection members. One of the connection members  20   a  (on the left segment  11  of  FIG. 3 ) projects longitudinally from the end of the segment  11 , and the other connection member  20   b  is situated inside the other segment  11 . In the position in which the two segments  11  are assembled together, the two connection members  20   a ,  20   b  are side by side, with their respective holes  21  in mutual alignment. A retaining pin  22  is engaged through the holes  21  as shown in  FIG. 4 , and it prevents the two segments  11  from moving apart. 
     Advantageously, one of the connection members (e.g. the projecting connection member  20   a  in  FIG. 3 ) is constituted in the form of a fork made up of two connection members flanking the opposite connection member  20   a . Assembly is thus obtained that is more stable and the pin  22  is fixed more securely. 
     In order to prevent the pin  22  from coming out in unwanted manner (e.g. when subjected to impacts or vibration), it is possible to add a safety cotter pin to said pin as shown at  23  in  FIG. 4 . 
     In order to facilitate access to the locking members  22 ,  23  from the outside, an opening  27  is provided, with a hatch  28  that can be opened and closed from the outside, in one of the walls  17  of the segment  11  that is equipped with the inside connection member  20   b , said opening being situated approximately facing the connection member  20   b , as shown in  FIG. 4 . 
       FIG. 5  is a diagrammatic axial section view through the boat, showing the two hull segments  11  in the assembly position. 
     In order to increase the rigidity of the hull and in order to optimize the performance of the boat in terms of stability and of course-holding, provision is made for each end of each of the stern and intermediate segments  11  and the end of the bow segment to be reinforced with a transverse plate (or floor stiffener plate)  24  that is substantially triangular in shape, and that may advantageously be constituted in the form of a perforated plate as shown in  FIGS. 3 to 5 , or that may be constituted by a truss. 
     As indicated above, the rigid hull segments  11  are assembled to the flexible bottom sheet  16  (embodiment shown in  FIG. 2 ) or to the flexible side flaps  7  (embodiment of  FIG. 1 ) by engaging a longitudinal rod (or bolt rope) carried by the flexible bottom sheet  16  or by the flap  7  into a longitudinal groove in the corresponding longitudinal edge of the segment  11 . In order to improve the strength of the coupling between each segment  11  and the flexible bottom sheet  16  or each flap  7 , provision is made to duplicate the means implemented, with, for each side, two parallel side-by side rods (or bolt ropes) engaged in respective ones of two parallel groves. Thus, as shown in  FIGS. 3 and 4 , the longitudinal edge of each of the walls  17  of each segment  11  is organized in the form of a shaped-section member provided with two parallel grooves  26 . 
     As indicated above, the above-described provisions can be applied particularly advantageously to boats of the  FIG. 2  type.  FIGS. 6 and 7  are shown respectively in a view from underneath, and in a fragmentary perspective view of the inside of a boat organized in this way. 
     In  FIG. 6 , it is easy to recognize the rigid central strip  6  made up, in this example, of three end-to-end segments  11 . 
     In order to improve the profile of the bow of the hull, a triangular flap or gusset  12  made of canvas and secured to the flexible bottom sheet  16  covers the forward end of the first segment  11  over which it is strapped. In addition, the gusset  12  serves to constitute locking means for preventing the segments from moving forwards. Furthermore, retaining means, in particular having straps (which are not visible in  FIG. 6  since they are hidden by the stern segment  11 ), are provided at the aft end of the stern segment  11  so as to lock it longitudinally. 
     Also in  FIG. 6 , the flexible bottom sheet  16 , which is applied against the panels  9  of the floor  3 , fits snugly over all of the significant pieces in relief of said floor  3 , and the imprints of the end-to-end edges  14  of the floor panels  9  show through it. 
     In view of the specific provisions explained above, a boat organized in accordance with the invention, and in particular the boat shown in  FIGS. 6 and 7 , can be disassembled easily, quickly, and without any special tools being necessary. In addition, the structural means implemented are simple and inexpensive to manufacture. 
     The hull constituted in accordance with the invention can comprise a number of rigid segments  11  that must not be too small so that each segment is not excessively long, or too large so that the assembly/disassembly time is not excessive. A number of segments  11  lying in the range two to four would seem to be suitable in general, and three segments would appear to be acceptable for a medium-sized boat. The number of hull segments  11  can be the same as the number of floor panels  9 .