| WO2003095297A1 | 2003-11-20 |
| US3874315A | 1975-04-01 | |||
| GB190902173A | 1909-07-01 | |||
| US3742888A | 1973-07-03 | |||
| EP0105819A1 | 1984-04-18 | |||
| FR2614261A1 | 1988-10-28 | |||
| US3316874A | 1967-05-02 |
| CLAIMS 1. Hull for high-speed boats characterised by the fact that it presents a surface with rectangular recesses (e), on the front side of which (a) there is a series of holes in dense formation and in the form of a crack. 2. Hull for high-speed boats in accordance with Claim 1. It is characterised by the fact that the recesses create repetitions in lines along the imaginary axis of the hull. 3. Hull for high-speed boats in accordance with Claims 1 and 2. It is characterised by the fact that the lines of the recesses are repeated in parallel formation among them, each line having a different inclination to the horizontal level. 4. Hull for high-speed boats in accordance with Claims 1, 2 and 3. It is characterised by the fact that each recess has a shallower part on its front side (a) where the holes are. It gets deeper towards the back, with a slight incline to about 3/4 of its route, point (b), and from this point it begins to decrease the depth with a slight curve downwards to the next side (a). 5. Hull for high-speed boats in accordance with Claims 1, 2, 3 and 4. It is characterised by the fact that among the polyester layers, there is incorporated a network of air piping with a scaled diameter, starting from the larger diameter at the front top part of the hull and ending at the holes on the sides (a). In this way, the specific design allows the air from the atmosphere to fill the spaces in the hull created by the recesses, not allowing vacuum to increase due to speed; thus, the water does not adhere to the whole surface of the hull, and the friction surface and resistance to the movement of the boat are reduced. 6. Hull for high-speed boats in accordance with Claims 1 , 2, 3, 4 and 5. Alternatively, this design can consist of plastic P.V.C. parts, which are detachable for easy cleaning and reattachment and shall be fitted on the central air pipes that exist on the hull and have non-return valves. This way, a more detailed rendering of the design is achieved and a more complex construction of the hull avoided. |
The invention relates to the design and construction of a hull that allows natural ventilation for the reduction of consumption and an increase in performance.
The rule that applies to date in the design and construction of a common hull for high-speed boats demands that this surface (the hull) be as smooth as possible, in order to achieve a reduction in the coefficient of friction when sliding over the water. The disadvantage, of course, of the above rule is that water makes strong bonds when it comes into contact with even very smooth surfaces.
As a result, the reduction of friction that is achieved by smoothing the surfaces on the hull of boats has very narrow margins for improvement, in other words very narrow margins for a further reduction in the coefficient of friction.
Starting out from the design of the hull with hydrodynamic characteristics, the basic element besides the shape is the reduction of the coefficient of friction created during the movement of the boat.
Taking into account water's increased bonding feature, that is to attach to surfaces that it comes into contact with, we try to reduce the surface of the hull that comes into contact with the water as far as possible, without creating instability in the behaviour of the boat during sailing.
So, we designed a hull that minimises contact with the water by interposing a layer of air on which the largest part of the hull moves, and at the same time this design creates anchorage and directivity points.
This is achieved with rectangular recesses (e) as in Fig. 1 , which run along the hull in parallel to its longitudinal axis.
It is slightly slanting with its deeper point at the back of the rectangle, while on its front side (a) it bears holes as in Fig. 1.
There is piping that ends at these holes, which are connected internally to a pipe of larger diameter, which runs along the imaginary keel of the boat, and has a nonreturn valve at its base, the free end comes into contact with the atmosphere via a valve, to offer the potential of reducing the amount of air provided or even isolation. The system works as follows: As we know from the Bernoulli principle, when there is a flow of liquids, pressure is inversely proportional to the speed of flow.
Thus, when the boat is moving over water, a vacuum is created on its hull, which increases as the speed of the boat increases.
This vacuum forces the air from the atmosphere to enter under the hull via the holes along the side (a) and create a Venturi effect.
The amount of air is proportionate to the speed of the boat, and it is supplied in such a way that the rectangular shapes act as air cushions, which the boat slides on.
In Fig. 2, the side view of the bottom part of the hull (x = direction of the boat), we show how these pressures work in accordance to our design.
At points (d) we have the highest pressure due to the lowest water speed.
At points (Y) we have the lowest pressure due to the largest water speed.
Immediately after points (Y) there are sides (a) with the holes at a backward angle, which create an intense air flow from the atmosphere towards the bottom of the hull, and in this way we manage to keep loose contact between the two surfaces, thus reducing friction.
Along the whole route from points (Y) to points (d) pressure is increased due to the continuous drop in speed that comes from the slightly upward slant of the hull, thus giving the water room to reduce the speed.
The spray rails (p) in Fig. 1 have a slightly downward slant, so that the air does not escape towards the sides, but gets driven towards the stern, thus keeping it along the whole length of the hull.
At the same time, they create stability and directivity for the boat.
The piping network is watertight and incorporated among the layers of Polyester + glass fleece, and there is a non-return valve at the base of the central pipe, so that water does not enter when the boat is not moving.
There is also a safety valve so that this can be deactivated, or if it is not necessary, the provision of air can be limited depending on the conditions of the journey.
On boats that have a greater draft or do not reach adequate speed, it is possible to install a pump to increase the air supply in the network.
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