Boat of the catamaran type, propelled mechanically
BACKGROUND OF THE DESCRIPTION 
     The present invention relates to a boat of the catamaran type, propelled mechanically, preferably with an outboard motor, which is light, uncapsizable, non-sinkable and entirely dismountable. 
     Numerous boats are known which comprise in tandem two floats connected by assembly means which are either rudimentary if a supple connection is desired, and in that case high speed is excluded, or very complex if a considerable rigidity is desired. Mechanically propelled catamarans are included in the latter case, of which the weight is further increased by the reinforcing elements for the motor support. This type of boat is therefore not propicious for frequent dismantlings by nonspecialized users. In addition, other conventional problems result from such boats, such as the weight which renders manipulations and transport difficult and increases the draught, therefore the power of propulsion and consequently the investment and exploitation costs. 
     SUMMARY OF THE INVENTION 
     All these drawbacks are largely eliminated by the invention which relates to a boat of the catamaran type, which is mechanically propelled, preferably by means of an outboard motor, characterized in that the two floats, which are advantageously identical, coplanar and parallel, and the seat of the motor are maintained rigidily together by assembly means comprising: 
     two tranverse bars disposed, perpendicularly to the axis of the floats, substantially at the front of the latter for one and at the rear for the other and fast with the floats in a dismountable manner by fitting in slots; 
     a central longitudinal member extending longitudinally between the two floats, preferably at equal distance therefrom, to connect the two transverse bars, at their centre, by suitable, dismountable fixing means so that the rear transverse bar is thus blocked in rotation in order to be able to support the seat of the motor, including when said bearing is offset rearwardly; 
     two lateral bows fast with the seat and extending on either side thereof, in an appropriate profile, up to the front transverse bar on which they are fixed in order to absorb the efforts of acceleration and to constitute a member for the passenger to hold, and 
     lower and upper fairings completing the boat by constituting a place to sit and for control. 
     Numerous advantages follow from such an embodiment, and in particular a reduction in the weight of the boat in a ratio that may attain 3 in comparison with conventional boats of the same type. This characteristic is obtained thanks to the simplification of the device for connecting the two floats which is strictly limited to two transverse bars joining the two floats, blocked in rotation about their axis by the central longitudinal element which contributes in addition to the reinforcement of the boat subjected to the longitudinal advance forces due to propulsion. Preferably constructed from stainless steel tubing, the connecting cradle is lightened, with the result that the boat with its motor and equipment presents a particularly reduced draught allowing a low power of the motor to take said boat to speeds comparable with conventional boats for pulling a water-skier. It is therefore easy to understand the decisive economic advantages of the invention since it requires reduced power, therefore much reduced investment to which is added a saving of fuel. 
     The means for fixing the floats and the transverse bars which have been retained are constituted by transverse bars, of length substantially identical to the overall width of the catamaran, fitting in slots which extend transversely to the front and rear of each float, on their upper surfaces, in accordance with the teachings of Applicants&#39; European Pat. No. 84 400 754.2. These slots which have a sufficient section to fit any thickness of the bars, present a shape following the exact shape of said bars. At each end of the bars, a vertical centering stud fast with said bars, predispose the two floats colinearly in rapid and reliable manner; a simple bolting on either side of the centering stud fixes each bar to the floats. In this way, the floats have no degree of freedom in their reciprocal movements, thus ensuring total rigidity of the whole, which is necessary having regard to the speeds that this type of boat may attain. 
     Nonetheless, it will be observed that the tapped holes provided in the bottom of each slot in the floats are obtained by embedding in the material constituting said floats, a metal insert taking the shape of said floats and presenting in its lower part an orifice adapted to receive the central stud of the transverse bars on either side of which extend two internally tapped vertical cylinders fixed to said insert at the level of the fixing holes provided to that end at each end of the transverse bars. This rigid assembly of the floats now being ensured, the central longitudinal element is placed in position by simple fitting on horizontal studs fast with the rear transverse bar after having traversed by sliding the front transverse bar by means of a bore provided to that end at the centre of said bar. The rear bar which is thus blocked in rotation by the central longitudinal element may receive the cradle for fixing the motor, preferably of the outboard type, this cradle being able to be at the level of the rear bar or offset rearwardly, thanks to a conventional triangulation abutting on the same rear bar. Cooperating in the rigidification of the whole system of assembly described hereinabove, two longitudinal bows are provided at the level of the axis of the floats; to that end, these bows join the cradle for fixing the motor to the transverse bar in a profile comprising curved sections giving the bows a certain longitudinal suppleness, performing the role of damper with respect to the effects of shocks and sudden acceleration; the curved forms of said damper bracing are unexpectedly and advantageously used to provide on the boat rails for the passengers to hold in safety. 
     Lower and upper fairing means advantageously complete the framework which has just been described, particularly for creating upper structures suitable for each user to sit and control the boat. 
     Thus defined, the boat according to the invention presents the advantage of being completely dismountable without resorting to specialists, which may be a solution to many a problem of handling, transport or care-taking. 
     In accordance with a complementary feature of the invention, floats are preferably used whose transverse section is rounded, thus differing from the known &#34;V&#34;-sections of the majority of catamarans. 
     This particular geometry of the floats which are encountered especially in wind-surfers, presents the advantage of reducing not only the resistance to advance but also the resistance of the boat to the lateral efforts due to the centrifugal force, thus causing veritable skids in sharp bends, are consequently avoiding any risk of capsizing the catamaran. 
     Furthermore, this type of float is well adapted to landing, this increasing the comfort of suche boats. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the present invention will be described hereafter by way of non limitative example with reference to the accompanying drawings in which: 
     FIG. 1 is a view in perspective of the cradle of the boat according to a principal variant of the seat of the motor. 
     FIG. 2 is an exploded view in perspective of the boat according to the invention, the principal parts being shown in a relative position of assembly. 
     FIG. 3 is an exploded view in perspective of the cradle of the boat according to another variant of the seat of the motor. 
     FIG. 4 is an exploded view in perspective of a transverse bar and of an insert in the forom of a gutter embedded in the material of the floats. 
     FIG. 5 is a view in transverse section showing a bar housed in its slot and bolted in the embedded insert. 
     FIG. 6 is a view in elevation of the boat according to the invention mounted with its fairings. 
     FIG. 7 is a front view of the boat shown in FIG. 6. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and firstly to FIGS. 1 to 3, the boat shown by way of example, according to the invention, is composed of two identical floats 1 made of a moulded material, preferably glass-fiber reinforced synthetic resin, maintained parallel, side by side, in the same horizontal plane. The floats are maintained in this way thanks to a preferably tubular assembly made of stainless steel comprising, on the one hand, transverse connecting means and, on the other hand, longitudinal reinforcing and blocking means. To that end, a first transverse bar 2, of round section and of sufficient diameter having regard to the mechanical stresses, ensure connection of the floats 1 in their front part and a second transverse bar 3, of the same section as the first, connects the rear parts of the floasts 1. These bars 2 and 3 are fitted in slots 4 of depth at least equal to the section of said bars, which are formed on the upper surfaces of the floats 1 during moulding thereof and which extend transversely over the whole width of the floats 1. 
     In accordance with FIG. 4, each end of the bars 2 and 3 is provided with a centering stud 5 fixed vertically in known manner beneath said bars 2 and 3 at the level of the median axis of each float 1 to fit in an orifice 6 made in the bottom of the slots 4 so as rapidly to obtain a reliable and predetermined transverse assembly. At the bottom, said slots 4 comprise, along their longitudinal axis, two tapped wells 7 disposed on either side of the centering orifice 6 to receive bolts 8 for fixing the bars 2 and 3 in accordance with FIG. 5. The bolts 8 traverse the bars 2 and 3 pierced to that end with smooth holes 9 each comprising, in its upper part, a countersink 10 adapted to countersink the hollow six-sided heads of the bolts 8, so that they constitute no superficial obstacle on the upper bridges 11 of the floats 1. 
     According to a particular arrangement retained for the invention, metal inserts 12, of omega cross-section, following the shape of the slot in their central part, having for effect to position the centering orifice 6 and to hold the tapped wells 7 by rendering them fast with the hull of floats 1, are embedded in the material constituting the floats 1. According to FIGS. 4 and 5, each insert 12 is provided, in its upper part, with horizontal flanges 13 embedded transversely beneath the upper face 11 of the floats 1. These flanges 12 advantageously comprise holes 13a reinforcing cohesion of the insert 12 in the slot 4. 
     Cooperating with these transverse connecting means, longitudinal means complete the assembly cradle of the boat according to the invention. To that end, a central longitudinal element 14, preferably constituted by two identical bars, of diameter substantially less than that of the transverse bars 2 and 3, made of stainless steel tubing, joins the transverse bars 2 and 3 in their central parts and thus blocks any possibility of axial rotation of the bars 2 and 3. Furthermore, the central longitudinal element 14, participating in the holding of the propelling member as will be set forth hereinbelow, longitudinally distributes the efforts of thrust and of resistance of the boat transmitted to the floats thanks to the transverse connecting bars 2 and 3 and to the slots asociated therewith. 
     So as to facilitate successive assemblies and dismantlings, the bars forming the central longitudinal member 14 are mounted in a horizontal plane, at the centre of the front transverse bar 2 and pependicularly thereto, by means of two horizontal diametral bores 15 in the bar 2 through which they slide to fit on two longitudinal studs 16, extending forwardly and fast with the central part of the rear transverse bar 3 which consequently loses all possibility of rotation on its axis. Consequently, it becomes possible to fix the seat 17 of the motor on the rear transverse bar 3 whether it is rearwardly offset as in FIGS. 1 and 2, or, according to a secondary variant shown in FIG. 3, is plumb with said bar 3. In the first variant, the seat 17 is supported by two tubes 18 fast with the bar 3 and advantageously disposed in line with the central bars 14 which particularly compensate the efforts of couple resulting from the assembly, completed in this sense by a double triangulation 19 and 20 conventionally joining the upper edge of the seat 17 to the bar 3, on the one hand, and to the central bars 14, on the other hand. In the secondary variant (FIG. 3), the seat 17 is connected to the bar 3 by two sets of vertical uprights 21 and 22 triangulated in conventional manner by arms 23 abutting on the longitudinal elements 14, and fixed by conventional means. 
     Borne at the ends of a horizontal and transverse bar 24, fast with the seat 17, of the same length as the bars 2 and 3, two vertical studs 25 cooperate, by fitting, in the rear fixation of lateral bows 26 contributing to the reinforcement of the assembly and for the passengers to hold. Front fixation of these bows 26 is obtained by specific screwing on the centering stud 6 of the bar 2 here participating in the control of the axial rotations. Furthermore, the bows 26, preferably made of stainless steel, have an appropriate longitudinal section. A first horizontal intermediate section 261 serves for transmitting the longitudinal stresses and advantageously as rail for the passengers to hold. A second rear section 262, vertical, comprises means for rear fixation of the bows 26 on the studs 25 fast with the seat 17. A third front section 263, of curved form, provides the bows 26 with their elasticity of deformation to the transitory stresses and accessorily a lateral clearance to facilitate access to the control station of the boat. 
     According to another feature of the invention, a first lower fairing 27, constituted by a plate of material of the same type as that of float 1, abuts on and follows the shape of the inner lateral faces of said floats, consequently obturating the intermediate space between floats 1. This fairing 27 is mounted beneath the boat be means of two counter-plates 28 and 29 which tighten the fairing 27, at the front and at the rear, on the central bars 14, by simple screwing at 30 and 31. 
     A second upper fairing 32 fits on the lower fairing 27 at the centre of the catamaran, to which it is fixed at the rear by a lug 33 bolted to the counter-plate 28 and, at the front, by an element 34 identical to counterplate 29, tightening the fairing 32 at the front end of the central longitudinal member 14. 
     This upper fairing 32, of appropriate one-piece form, comprises specific and known means for controlling the propelling member, such as throttle control lever and steering wheel 38 connected in conventional manner by cables and pulleys 39 to the outboard motor of which the horizontal rotation determines the direction of the boat. This same upper fairing 32 presents at its centre a recess 35 advantageously in the form of a driving seat and a rear part having the general form of a saddle for a passenger to sit astride, the two lateral bows 26 contributing to holding this passenger safely. 
     A complementary feature of the invention follows from the type and shape of the floats 1 with which the boat is equipped. 
     According to FIGS. 6 and 7, the hull of the floats 1 is preferably substantially semi-cylindrical inform, as is shown in conventional windsurfers, as opposed to the more traditional &#34;V&#34; sections in catamarans. This particular arrangement of the floats 1 reduces on the one hand the resistance to advance thanks to the resulting small draught and, on the other hand, the resistance to lateral thrusts in bends resulting from the centrifugal force which causes the boat to &#34;skid&#34;, thus avoiding the catamarans capsizing. 
     Finally, this rounded form of the hulls of the floats accessorily allows landings without risk of deterioration, thus enabling this type of boat to be employed for all types of use.