Abstract:
A semi-rigid boat, includes a rigid hull ( 11 ) provided, at the bridge thereof ( 6 ), with two types of holders for the inflatable tube(s): a gutter-shaped holder for receiving, at the bow and/or at the stern, a section ( 13, 14 ) of tube ( 12 ) having a circular cross-section; and a planking wall-shaped holder ( 16 ) that extends between the bow and the stern, which is provided so as to engage with an inflatable section-shaped structure ( 15 ) having a D-shaped cross-section that extends longitudinally between the sections ( 13, 14 ). The section ( 15 ) of inflatable tube having a D-shaped cross-section is attached to the bottom portion and to the top portion of the planking wall ( 16 ).

Description:
OBJECT OF THE INVENTION 
     The invention relates to boats that are semi-rigid, meaning boats with a hull of rigid material and an upper side wall (also referred to in this document as planking) consisting of one or more inflatable tubes. 
     PRIOR ART AND PROBLEMS 
     Semi-rigid boats combine the advantages of inflatable boats and boats with a rigid hull. 
     The cylindrical tubes that form the upper side wall have a circular cross-section when inflated and their diameter is approximately 50 to 60 cm, which provides very good buoyancy. The midship section in this type of boat is very large while the weight and bulk are relatively moderate when the tubes are deflated. The stability of this type of boat feels reassuring and safe to passengers. In addition, the rigid hull is protected by the presence of inflatable tubes which extend from the bow to the stern. 
     However, this combination of rigid hull and inflatable tubes has disadvantages which are related to the presence of the inflatable tubes. 
     These tubes overlap the part of the rigid hull which corresponds to the deck of the boat. The effective useful floor space on the deck is reduced accordingly. 
     The ratio between the usable surface area and the surface area attached to the perimeter of the boat is not as good as it is in a boat with a rigid hull. 
     Advantages of the Solution According to the Invention 
     The invention proposes an arrangement for this type of boat which substantially improves this ratio between the usable surface area and the surface area attached to the perimeter of the boat, which allows increasing the usable space inside the boat. This increase makes it easier to move about on board, or allows installing additional equipment such as seats, or allows improving motor accessibility or possibly installing larger motor(s) for boats with an in-board motor. 
     The invention proposes an arrangement which removes almost none of the buoyancy or safety characteristics of this type of boat, and this arrangement maintains the characteristics concerning the impact resistance of the boat both at the bow and at the stern, and even on the sides. 
     Solutions Provided by the Invention 
     The boat of the invention comprises a rigid hull associated with one or more inflatable tubes which act as upper side walls, and said rigid hull has the characteristic of comprising two types of holder for this or these tubes, at its deck:
         a gutter-shaped holder for receiving, at the bow and/or stern, a section of tube having a circular cross-section, said holder being positioned substantially at the level of the deck, cooperating with a longitudinal portion of the cylindrical envelope of said bow and/or stern section,   a holder in the form of an upper side wall segment which extends between said bow and said stern, arranged to cooperate with a structure in the form of a section of inflatable tube which extends longitudinally between said bow and stern sections, said holder in the form of a wall segment extending to a height which substantially corresponds to the diameter of said bow and stern sections and its lateral position being such that its outer face is located substantially in the vertical mid-plane of said bow and stern sections.       

     In the invention, the structure in the form of a section of inflatable tube which is associated with the upper side wall segment has a D-shaped cross-section of which the flat face is applied against the outer face of said upper side wall segment and the curved face is positioned as an extension of the outer portions of the bow and stern sections. 
     Still according to the invention, the section having a D-shaped cross-section is attached to the lower portion and to the upper portion of the upper side wall segment. 
     Advantageously, the lower portion of the section having a D-shaped cross-section comprises a bolt rope which is threaded in a groove in the rigid hull, said groove being arranged in the lower portion of the upper side wall segment. 
     In this case, advantageously, the bolt rope located in the lower portion of the section having a D-shaped cross-section can additionally be an extension of the bolt rope of the bow and/or stern sections, and the groove accepting said bolt rope can extend for the entire length of the rigid hull. 
     Advantageously, the upper portion of the section having a D-shaped cross-section comprises a fabric band which is either slipped into a track, or bolted onto the upper portion of the upper side wall segment, with a metal strip placed between them. 
     Also advantageously, the section having a D-shaped cross-section extends, between the bow and the stern, for a length corresponding to at least half the length of the boat, with a major portion of the length of said section arranged on the stern side. 
     In another arrangement of the invention, the section having a D-shaped cross-section consists of a single inflatable tube, delimited by the fabric attached to the upper side wall segment and by fabric which, in the inflated state, forms an arc that is an extension of the bow and stern sections, said tube being a single tube. 
     In a variant embodiment of the invention, the section having a D-shaped cross-section comprises at least two inflatable volumes, one of said volumes consisting of a substantially vertical inner part with an inflatable volume of watertight cloth or fabric having two parallel faces, forming, in the inflated state, a tube shape with a substantially elongated rectangular cross-section, fixed and attached by its inner face to the outer face of the upper side wall segment, and the other of said volumes, the outer part, consisting of an inflatable tube having a D-shaped cross-section, fixed and attached by its flat face to the outer face of the two parallel faces of the inner part, meaning the outer face of the inner inflatable tube. 
     Additionally or alternatively, the inflatable tube or tubes is/are assembled with the upper side wall segment, to its upper portion and its lower portion, by means of flexible angle attachments, preferably of watertight fabric or cloth, glued directly to said upper side wall. 
    
    
     
       DESCRIPTION OF FIGURES ACCOMPANYING THE DESCRIPTION 
       The invention is detailed in a sufficiently clear and complete manner in the following description to enable its implementation. This is accompanied by drawings, in which: 
         FIG. 1  is a plan view of the left half of a conventional semi-rigid boat; 
         FIG. 2  is a plan view of the right half of a semi-rigid boat arranged according to the invention; 
         FIG. 3  is a transverse cross-sectional view of a tube having a circular cross-section, arranged at the stern or the bow of the boat; 
         FIGS. 4   a  and  4   b  are transverse cross-sectional views of variants of the inflatable tube section having a D-shaped cross-section according to the invention:  FIG. 4   a  shows a single inflatable tube with a D-shaped cross-section, attached to a wall segment acting as the upper side wall, and  FIG. 4   b  shows an inner inflatable tube with a rectangular cross-section, attached to said upper side wall segment, with an outer inflatable tube having a D-shaped cross-section, attached by its flat face to the outer flat face of the inner tube; 
         FIG. 5  shows a perspective view of a tube according to the invention, acting as an upper side wall; 
         FIG. 6  shows a system for assembling the tube onto the semi-rigid hull at the cylindrical portions of said tube; 
         FIG. 7  shows an attachment of the lower portion of the tube section having a D-shaped cross-section, onto the rigid hull; and 
         FIG. 8  shows an attachment of the upper portion of the tube section having a D-shaped cross-section onto the wall segment serving as an upper side wall. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The boat, or craft, represented in a schematic illustration in  FIG. 1  in a half-plan view, comprises a rigid hull  1  and an upper side wall in the form of an inflatable tube  2 . Said tube may possibly comprise several separately inflatable compartments. 
     This inflatable tube  2  extends between the bow  3  and the stern  4 , and its cross-section is circular for the entire length of the upper side wall. This tube  2 , as represented in  FIG. 3 , rests on a holder  5  in the form of a gutter which runs peripherally along the rigid hull  1 , at the edge of the deck  6 . 
     This holder  5  has a cross-section in the form of an arc in order to hold a portion of the cylindrical envelope of the tube  2 , specifically a longitudinal strip along the lower portion of said tube. The tube  2  comprises a bolt rope  7  running along its length, which, as represented in  FIG. 6 , engages and cooperates with a guide track  8  arranged along the outer edge  9  of the rigid hull  1 , at the intersection of this edge  9  and the edge of the holder  5  surface. The tube  2  can also be attached by appropriate means to the other edge of the holder  5  and in particular to the inner edge  10  located next to the deck  6  of the boat. 
       FIG. 2  shows the boat of the invention in a half-plan view. It comprises a rigid hull  11  and a tube  12  in which the cross-section changes between the bow  3  and the stern  4 . The tube  12  comprises several sections which form a continuity:
         a front section  13  at the bow  3 , having a circular cross-section as represented in  FIG. 3 ,   a rear section  14  at the stern  4 , also having a circular cross-section, with a diameter that is the same as or is noticeably greater than the diameter of the front section  13 ,   and, between the two, a section  15  having a D-shaped cross-section, said section  15  pressing against a wall segment  16  extending up from the deck  6 , at the edge  9 , along the periphery of the rigid hull  11 , with the deck  6  and the edge  9  as well as the holder  5  being analogous to those of the hull  1  of  FIG. 1 .       

     This section  15  extends for a length which corresponds, for example, to at least half the total length of the boat, and is located essentially towards the back, meaning towards the stern of the boat, in the area of the deck  6  which contains the seats for example. 
     The section  15  may comprise a bolt rope  17  in its lower portion, as represented in  FIG. 7 , said bolt rope  17  being positioned for example as the extension of the bolt ropes  7 , analogous to those of the boat in  FIG. 1  and arranged on the sections  13  and  14 , ensuring continuity with them. Similarly, the groove  18  arranged on the edge  9  of the hull  11 , in the lower portion of the outer face  19  of the wall segment  16 , can extend and be continuous with the groove  8 , analogous to the groove of the boat in  FIG. 1 , and arranged in the stern and bow of said hull  11 . 
     In the upper portion of the wall segment  16 , the section  15  can comprise a supplemental band  20  forming an angle bracket, said band  20  being assembled onto the upper end of the wall segment  16  by means of a screw  21  with, for example, a metal strip  22  inserted between them. 
     This section  15  can consist of a single volume, as represented in  FIG. 4   a , or may comprise multiple separately inflatable volumes as represented in  FIG. 4   b.    
     In  FIG. 4   a , the section  15  having a D-shaped cross-section consists of a single inflatable tube having a D-shaped cross-section, directly attached and fixed, for example by gluing, by its substantially vertical flat face to the outer face  19  of the upper side wall segment  16 , while its curved face is an extension of the outer portions of the front  13  and rear  14  sections of the tube  12 . 
     In  FIG. 4   b , one of the two inflatable volumes consists of an inner substantially vertical part having an inflatable volume of H 2 P fabric, meaning a watertight fabric with two parallel faces, and the other one, the outer part, consists of a float having a D-shaped cross-section. Thus one obtains an inner inflatable tube  26  which when in the inflated state has a shape that is substantially parallelepipedic with a transverse cross-section that is a substantially vertically elongated rectangular form with rounded corners, directly attached, for example by gluing, to the outer face  19  of the upper side wall segment  16 , by the face constituting the inner face of the two parallel faces of watertight fabric or cloth which delimit the inflatable tube  26 , while the outside portion consists of an outer tube  25  having a D-shaped transverse cross-section in the inflated state, directly attached and fixed by its substantially vertical flat face to the outer surface of the inner inflatable tube  26 , meaning against the face of the two parallel faces of watertight cloth or fabric of this tube  26  which constitutes its outer face. 
     In other words, the inflatable float of the section  15  having a D-shaped cross-section is a float consisting of two inflatable tubes, one of them an outer tube  25  having a D-shaped cross-section attached by its flat face to the flat outer face of an inner tube  26  having a substantially rectangular cross-section elongated in the vertical direction, which is itself attached by its flat inner face to the outer face  19  of the upper side wall segment  16 . 
     An embodiment according to  FIG. 4   b  with two inflatable tubes  25  and  26  forming the section  15  having a D-shaped cross-section offers the advantage of improving the impact resistance and safety of the boat. If the outer tube  25  is torn or accidentally deflated, there is still the remaining inner tube  26  which continues to provide a reduced buoyancy that is sufficient to keep the boat afloat. 
       FIG. 5  shows the general appearance of a tube  12  of the invention. This tube is represented in a perspective half-view. It shows the section  13  having a circular cross-section arranged at the bow  3  and the section  14  having a circular cross-section arranged at the stern  4 , and between the two, the section  15  having a D-shaped cross-section establishing the continuity between sections  13  and  14 . 
     One can also see, in the lower part of the tube  12 , the bolt rope  7  for the sections  13  and  14  and the bolt rope  17  for the section  15 , said bolt ropes forming a single bolt rope extending for the entire length of the three sections. 
     The upper part of the section  15  comprises a band  20  by which it can be attached to the upper portion of the upper side wall segment  16  of the rigid hull  1 . 
     As a variant, instead of attaching the lower portion of the section  15  having a D-shaped cross-section by a bolt rope  17  in a groove  18  and attaching the band  20  on the upper end of this section  15  to the upper end of the upper side wall segment  16  by screws  21 , with a metal strip  22  placed between them, the section  15  having a D-shaped cross-section, consisting of one or multiple inflatable tubes, can be attached at its upper part and its lower part to the upper side wall segment  16  by means of flexible angle attachments of cloth or fabric, which are glued directly to this upper side wall segment  16 . 
     A significant increase in spaciousness is obtained for this type of boat, as one can see in  FIG. 2 , when compared to  FIG. 1 . The half-width L 11  of the deck  6  at section  15  in  FIG. 2  is greater than the half-width L 1  of the deck  6  in  FIG. 1 , and the ratio of the surface areas within this zone is on the order of 30 to 40% greater for the boat according to the invention.