Patent Publication Number: US-2005115485-A1

Title: System for improving the manoeuvrability of a boat&#39;&#39;s hull and for reducing its friction with water

Description:
TEXT OF THE DESCRIPTION  
      The present invention is about a system for reducing the friction with water of a boat&#39;s hull, having the double outcome of increasing the service speed and of reducing the forces which act on the hull and consequently cause its wear.  
      The movement of a body in an also moving incompressible fluid mass, and more specifically the movement of a boat in a stretch of water, it too subject to a movement such as the wave motion of the sea, responds to very complex physical laws which have been studied and developed by the field of hydrodynamics, the forces acting on the boat being numerous, among which friction has a considerable importance that is caused on its turn by many different factors.  
      It is clear and obvious that a body advancing in the water comes up against a resistance which is much greater than the one found in the air, and therefore the speed of boats are much lower than the speed of air or land vehicles.  
      Therefore the speed increase of a boat can be accomplished only by reducing the forces generated by the water which act on the boat. In order to achieve this object, up to now all the efforts were focused on raising the penetration coefficient by designing hulls which were as more tapering as possible, by reducing to a minimum the immersed part of the boat (catamarans) or by lifting it from the water during navigation (hydrofoil, hovercraft). In order to reduce friction, so far it has only been thought of designing hulls with the most possible polished and smoothest surfaces, as well as repellent to incrustations which also slow down the water sliding in addition to damaging the hull.  
      The present invention&#39;s object is that of tackling the friction problem in a revolutionary way, by equipping the boat with a mechanical system which helps the hull sliding over the water mass with the least possible friction.  
      This principle is valid for floating watercrafts as well as for underwater vessels.  
      The solution offered by the present invention arises from observing a similar concept applied to the case of solid bodies. If some freely rotating elements, hence moving with respect to one another, are interposed between two solid bodies, a (rolling) friction between the bodies will be created, being much lower than the (sliding) friction generated by their mutual slipping. The concept is thus that of applying the principle of the wheel to a watercraft, and the present invention describes the means necessary for making the hull slide on the water almost as if it were a road vehicle.  
      The system according to the present invention therefore provides a number of freely rotating bodies, arranged on the hull&#39;s surface, which take up the majority of the forces exerted by the water flow on the boat.  
      Such bodies consist of bodies of revolution, such as balls, cylinders, spheroids, which are lodged in their corresponding housings made out of at least part of the hull and are made to rotate by the surrounding water, thus transforming the pressure and wake energy of the liquid mass into rotation work.  
      Said rotating bodies can be arranged on any part of the hull. It is obvious that those which are more important for reducing friction are placed on the stem and on the broadsides up to the boat midship section, preferably from the keel up to the waterline, but it is not excluded that the application of further rotating bodies also on the stem could bring additional improvements. Furthermore, such rotating bodies can also be applied on the very own keel or bottom of the boat, in order to facilitate the operations of laying up and of beaching small watercrafts, by assuming in this case the proper function of wheels or sliding rollers.  
      Therefore, the main object of the invention is reducing both the global friction generated by the hull which is in continuous contact with water and the temporary friction areas on the strand zone, generated by the rising and falling of the waves.  
      Another object is the reinforcement of the hull&#39;s structure, thanks to the housing that lodge the freely rotating bodies, which increase the resistance and the elasticity of the same hull, at the same time guaranteeing the absorption of the hits caused by the waves. This occurs thanks to the main effect of dispersing the energy and the force of the breakers on the hull (the rotating body freely rotates by offering the least resistance to its endless rotation at each contact with the fluctuating movement). In this manner also the force of the most violent wave motion is cancelled out by the continuous free motion of the rotating bodies and the variation of the waves&#39; stream is instantaneously absorbed by them.  
      A further object is the reduction the consumption of paints and of metal or plastic materials of the hull&#39;s structure thanks to the intense and continuous reduction of forces of friction, dispersed by the rotating bodies.  
      The materials used for making the rotating bodies can be any matter fit to achieve the desired result, without creating undesired secondary effects, such as for example the formation of rust due to the use of iron materials. The materials can be either firm or soft enough to absorb the impact with the medium or with other structures.  
      The size of the rotating body must be compatible and proportioned to the boat&#39;s total dimensions, without being an obstacle to the movement of the boat itself.  
      The size of the parts protruding from the hull (the outer part of the bodies) are minimum but enough for the attainment of the free movement, without becoming a potential cause of break down during the manoeuvres, or during the casual contact with harbour or navigation structures, or even spontaneously during the navigation. This latter action is particularly supported by the material employed, fit to absorb the boat&#39;s impact with the other materials present in the harbour, including the possible laying up. More specifically the outer dimensions must always guarantee the best possible impact with the water.  
      The inner dimensions can be varied according to the vessel but they can not be disproportionate with respect to the hull. This means that, except for a minimum outer part, the containment structure of the rotating body is incorporated in the hull, with the possibility of protruding inside the boat.  
      As for the number of rotating bodies to apply to the hull, the same considerations made for the dimensions are valid, meaning that the total number must be compatible with watercraft&#39;s size and must not represent an obstacle to its navigation.  
      More specifically, the rotating bodies should always guarantee the best impact and contact with the water or with said liquid medium.  
      The arrangement of the rotating bodies can be carried out with various modes: 
          1) continuously, in order to cover the whole boat&#39;s hull or the part in contact with the water or with said liquid medium;     2) On rows, with free spaces between them: 
            a) Perpendicular with respect to the navigation axis and to the direction of boat&#39;s motion;     b) Tilted backward with respect to the axis of navigation and of the boat, with different angles, to be defined based on the boat&#39;s speed and typology;     c) Mutually staggered;     d) With broken lines;     e) With interrupted lines;     f) With waving lines.    
               

      At last, the structure of the rotating bodies must be such that they are freely rotating inside a housing made of a material which does not reduce, or does it in a small amount, the free rotation of the rotating body.  
      There are many and different possible materials to be employed: metal, preferably not iron so as not to cause any problems related to the formation of rust, plastic matter, rubber, vegetal, or of natural origin, even obtained through genetic engineering with various combinations between them in order to achieve the best free rotation effect of the roller, so as to absorb the forces exerted by the water flow on the boat.  
      The description of some examples of the system according to the invention now follows, but it must be noticed that it is just a matter of giving a visual demonstration of how this system can be put into practice, however such illustrations must not be construed in any way as restrictive or comprehensive of the numerous embodiments that the system can take up in the general model of arranging rotating bodies on a boat&#39;s hull in order to reduce the friction with water and increasing the speed.  
    
    
      In the annexed drawings, the proportions are obviously completely distorted and only provide for an illustration of some possible embodiments of the system.  
       FIG. 1  is an example of the rotating bodies consisting of cylindrical rollers put on a considerably big ship;  
       FIG. 2  is an example of the rotating bodies consisting of balls put on a small cabin watercraft;  
       FIGS. 3 and 4  diagrammatically show the stem of a boat with different arrangements of the rotating bodies;  
       FIG. 5  shows a ball  10  freely rotating inside its housing  12  closed by a plate  14  fixed to the hull  16  through bolts  18  and equipped with seals  20  and a small bleeder  22  of the potential condensates and residuals built up in the housing;  
       FIG. 6  is a similar view of  FIG. 5  but wherein the ball  10 A rotates around a fixed axis  24 ;  
       FIG. 7  is a similar view of  FIG. 5  but showing a freely rotating cylindrical roller  26 ;  
       FIG. 8  is a front view of the roller of  FIG. 7  but with a detail of the seal  20 A;  
       FIG. 9  is a similar view of  FIG. 7  but showing a cylindrical roller  26 A rotating around a fixed axis  24 A;  
       FIG. 10  is a front view of the roller of  FIG. 9  with a detail of the seal  20 A;  
       FIG. 11  shows a freely rotating ball  10 B applied inside a threaded housing  28  which is part of the bulkheads such as those of an oil-tanker&#39;s hull; and  
       FIG. 12  shows two freely rotating balls  10 C made of a plastic material applied inside housings  12 C of a fibreglass hull of a small recreational water vessel, closed by a plate  14 C which is simply pressure applied from the outside for closing the housing  12 C. This solution is particularly easy and cheap and is especially suitable for small watercrafts. 
    
    
      Clearly, the practical details of the making of the system should be studied each time according to the type of water vessel, of their shape and of a great number of other variables, like the possible effects on the boat&#39;s performance, such as the floating, the turning, and during the turbulence caused by the medium, without falling out of the main scope of the invention consisting in the application of rotating bodies to a boat&#39;s hull, as it is also recited in the appended claims.