MC1594A1 - FAST BOAT - Google Patents

Description

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FAST BOAT.

The present invention relates to the improvement/performance of fast motorboats and it aims at a combination of construction features 5 applicable to fast boats with front or traditional propulsion, intended to improve their performance, that is to say to increase their speed for a given power and/or consumption of their engine to reach and maintain a given speed.

10 By "fast boats", we mean in the meadow

The patent covers fast boats for civilian purposes, such as fishing, pleasure boating, passenger or cargo transport, as well as ships of various sizes for military surveillance 15 or assistance purposes, ships for transporting and landing equipment and personnel, patrol boats, attack and rapid intervention craft, this list not being exhaustive, but rather illustrating only a few examples of the 20 very broad field of application of the invention.

Besides the resistance due to the hull shapes, the main reason for the relatively low efficiency of classic boat types lies in the large surface area of contact between the hull and the water, the friction of which implies an energy loss considered unavoidable.

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These frictions result from the effective contact of the water with what is called the "wet surface" of the hull, and all efforts to solve this problem had to aim at creating between the hull and the water a layer of air eliminating this contact.

But if we exclude, of course, the craft moving on a thick "mattress" of air forced under the bottom of the hull and trapped by a skirt following the periphery of the craft, and which can no longer in fact be considered 10 as boats, since moving indifferently completely above the water or dry land without contact with either, the only attempts really oriented towards a solution to this problem have always used partial and insufficient means to achieve the desired result.

The applicant has succeeded, following numerous real-world tests, in assembling all the necessary elements to achieve these results, and the subject of this application is therefore a fast motorboat 20 incorporating all the essential elements, namely:

1. A hull whose bottom has, over most of its length, a transverse profile in the shape of a flattened arch.

2. This bottom having, over most of its length, a series of steps.

3. Most of these steps have one or more openings on their rear face, each of which communicates airtight with the atmospheric air, via hollow frames and/or substantially

30 verticals.

4. The two sides of the boat being extended downwards by a skirt whose maximum height is substantially equal to that of the steps and preferably substantially parallel to each other longitudinally.

35 These essential means can be combined

Optionally, while remaining within the scope of the invention, one or more of the following subsidiary means:

5. The vault mentioned in (1) above has a practically constant transverse profile.

6. The steps mentioned in (2) above are created by vertical breaks in the longitudinal profile of the boat, and the opening mentioned in (3) above is created by this break.

7. The offset mentioned in (6) above may be made either in a straight line along a plane perpendicular to the longitudinal axis of the boat, or in any other shape or orientation, provided that it is symmetrical

to the axis of the boat.

8. The opening mentioned in (3), (6) and (7) above may occupy only a fraction of the transverse dimension of the step, and may or may not be subdivided.

9. The height of said opening and/or said cdan may be modified, this modification being able to go as far as the total closure of said opening.

10. In each opening, guide vanes can be mounted which can themselves be adjusted in orientation.

11. The longitudinal profile of the vault mentioned in (1) is preferably rectilinear.

12. The cross-sectional profile of the vault mentioned in (1) can be subdivided into two or more arches.

13. The rear area of the vault can be raised over a certain part of its length, following a straight longitudinal profile, a broken line and/or a curvilinear profile, the vault being able, in the corresponding portion, to retain its previous profile or to present a different profile, more or less flattened depending on the effects sought.

14. A transverse step with an opening, as defined in (2), (3) and (6), (10) above, determines the origin of this portion of the rear area.

15. The height of the skirts mentioned in (A) may be increased to compensate at least partially for the raising of this rear area.

16. The propulsion device(s) are mounted in the front part of the boat, possibly in a steerable manner.

The first four features, once the boat has primed its engine and reached a certain speed, cause air to be drawn in through the hollow frames and/or the aforementioned tubing, thanks to the low pressure created by the chines. This air is then displaced aft through the slots in the chines by the boat's forward movement and retained under the hull as a thin layer delimited by the upper keel and the side skirts, thus eliminating the aforementioned wetted surface. Other, optional features enhance the effects produced by the first four. In particular, the

Raising the stern prevents the bubbling and turbulence that would occur in that area when this layer of air escapes, slowing the boat's forward motion. Finally, it is preferable for the propulsion system(s) to be located away from the area where this phenomenon is created, which favors their position in the forward part of the hull.

11 It should be noted that the applicant has already made attempts in a similar direction, as described in her French patent 80.18759 of August 29, 1980. However, all the elements of the combination had not yet been brought together, because the supply of air under the hull required the use of additional means of blowing and pumping, and not its aspiration by the simple effect of depression created by the steps, which were not envisaged at all in this earlier patent.

•Conversely, it should also be noted that although such steps were described in the US patent

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1,831,697, in the latter case they were of variable height, and above all very low, so they could not cause a sufficient suction effect, so that the air blown under the hull actually came from the dynamic effect created by the speed in a single intake opening.

the bow of the boat, an effect which has since been measured and found to be too weak for the intended purpose. Moreover, an additional fan or propeller was planned at that time to create a sufficient positive current. Finally, the small amount of air thus brought under the hull immediately escaped laterally, as the shape of the bottom had neither an arch nor a lateral skirt, and therefore had no effect on the boat's behavior.

Obviously, since the phenomenon used in the present invention had never actually been created and observed, the importance of the stern lift could not have been taken into consideration. However, it has been observed that, complementing the effect of the flattened arched hull, this lift gives rise in this area to a nozzle effect acting on the air which, instead of escaping erratically, creating the bubbling and eddies that usually slow boats down, is released upwards to the outside to such an extent that experience shows that the boat leaves practically no wake or transom wave behind it. 25 No prior document mentions such a combination of means and the effects it creates, which can be described as synergistic, since it is not an addition of already known individual effects, since none could have been effectively created individually, none of the said 30 individual means having been used identically to the form it takes here in the present invention, jointly with the others.

We will now describe the invention in more detail, with reference to the following description, corresponding to the attached drawing on which:

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- Figure 1 is a cross-section through the vertical plane of longitudinal symmetry of a shell exhibiting the characteristics of the invention,

- Figure 2 is a schematic view from three 5/4 views below the same hull.

- Figures 3 to 7 are cross-sections of the same hull, taken along the vertical planes III-III to VII-VII of figures 1 and 2,

- Figures 8a and 8b represent tenfold variations of figure 4,

- Figure 9 shows a detail of Figure 5, on a larger scale.

- Figure 10 illustrates an optional additional arrangement of the bow of a boat according to the invention,

15 - Figure 11 illustrates a variant of the propulsor used in the invention,

- Figures 12 to 15 schematically illustrate variant shapes of the skirts provided according to the invention,

- Figure 16 illustrates a variant of the layout of the rear of a boat according to the invention,

- Figures 17 to 20 illustrate various configurations of the boat's propulsion system according to the invention,

- Figures 21 and 22 illustrate another 25 variant of the propulsion system arrangement according to the invention,

- and figures 23a and 23b illustrate yet another variant of the propulsion system.

We will first describe the invention in principle by referring to figures 1 to 10, where the same references obviously designate the same elements, although the scales of these figures are different.

The hull of a boat according to the invention is usually composed of two sides 1 and 2 following the successive profiles of the transverse frames, joined at the bow 3 and at the table 4, and closed by a bottom 5.

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According to a first essential component of the combination of features which defines the invention, the bottom 5 is connected with a number of frames such as 6, 7, 8, 9, so as to create a series of steps 10, 11, 12, 13, the first of these frames being located approximately towards the first forward quarter of the boat.

According to a first essential component, of this combination these frames constitute hollow frames, opening to the air towards their upper part either directly, or by vertical tubes (not shown) and forming at their lower part a box whose rear face, constituting the corresponding step by the offset of the bottom, has a transverse opening, preferably equipped with guide vanes designated by 14 in particular on figures 5 and 9. As can also be seen on these figures, these vanes are preferably closer together towards the outside than towards the inside of the hull.

According to a third essential component of this combination, sides 1 and 2 extend beyond the level of the bottom 5, so as to form two skirts 15 and 16, the form and function of which will be described in more detail below.

According to the fourth essential component of this combination, the bottom 5 takes the form of a flattened or crushed vault 17 which, particularly in the case of large boats, can be subdivided into two half-vaults 18, 19 (fig. 8a) or even into three partial vaults 20, 21, 22 (fig. 8b) joined by keels or reinforcements 23 (fig. 8a) or 24, 25 (fig. 8b), it being understood that these keels are always located above the horizontal plane H of the bottom of the skirts 15 and 16, which fundamentally distinguishes this bottom shape from the so-called "gull wing" shape, the central part of which is clearly lower than the lateral parts. In other words, the bottom 5, as a whole, is

always above the base plane H of the skirts.

According to an optional component of this combination, the rear area 26 of the bottom 5, while retaining the same arched transverse profile, 6th rises towards the table 4, the skirts 15' and 16' then taking on a height such that their lower part remains submerged.

To these 15', 16' skirts can be articulated: vertical axis rudders, contributing to the orientation of the boat.

Finally, according to an important component of this combination, the boat's propulsion system, represented here as a propeller engine 27 carried by a pylon 28, is preferably located at the front, namely shortly before the first hollow frame 6.

It is the fundamental combination of the first four indispensable components that represents the essential characteristic of the invention, that is to say, which alone, and taken in its entirety, ensures the exceptional advantages of this new boat, for the reasons and under the conditions that will now be described and explained in more detail.

Under normal operating conditions the propeller 27 moves the boat forward in the usual way at a fast speed, this <pi i initiates a depression phenomenon at the rear of each step 10, 13.

This depression causes the air above the boat to be drawn in through the openings in the chines and the hollow frames 6, 9, and an aerodynamic system is installed in which air drawn from the atmosphere is expelled by suction through the opening partitioned by the paddles 14 against the bottom 5, from which it cannot escape laterally due to the skirts 15, 16, so that it is expelled towards the rear, creating over the entire surface of the bottom 5 a layer of air that eliminates the "wet surface" of this bottom. The other components of the invention improve this evacuation. Indeed, the rear area of the hull, in which the raised shape of the bottom at 26 creates a venturi-type nozzle effect, with air being ejected upwards, reduces the turbulence or bubbling that slows the boat's progress. The boat thus "planes" on a layer of air a few centimeters above the water, which, exerting no resistance from the first step onwards, allows it to achieve quite exceptional and unexpected performance, as will be explained later, and which is far superior to that of otherwise similar boats but lacking the characteristics of the invention. It should be noted that the optimal inclination of the bottom 26 to the horizontal is between 2 and 10 degrees. For clarity of the drawing, this angle is greatly exaggerated in Figure 1. This essential structure can, of course, be implemented in numerous variations, designed to further improve the boat's performance or to adapt it to its intended use. Thus, there may be only one hollow frame, which can be either the first one, at the bow, or the last one, just before the stern rises. As the thickness of an opening or slot is one of the elements that determines the volume of air flowing out of it, this thickness can be constant or variable for the same slot and can also differ from one slot to another. Since openings can take the form of slots, they may, by extension, be referred to as such in this text. The edge of these openings can have a particular shape depending on the desired effects, in order to obtain, for example, convergence or divergence, or a constant cross-section and/or a specific direction of the air flowing out. This thickness will depend on various parameters, including the spacing of the slots, their width, and the boat's speed. For example, slots approximately 5 cm wide, spaced every 3 meters, yield interesting results at around 25-30 knots for a width of 2.5 meters. Indeed, the purpose of the openings or slots is to generate the best possible distributed airflow under the hull. Since various effects, notably the slope of the compressed hull arch, which varies according to its transverse position, combine to cause the incoming air to collect towards the center of the arch, it is advisable to promote airflow in the lateral sections of the arch, particularly by widening the slots there or by positioning the vanes where these slots span the entire width of the arch. In any case, the distribution of the airflow under the hull depends on numerous factors, including the boat's speed. Like the rest of the hull, the transverse profile of the bottom of the hull must be symmetrical with respect to the vertical plane passing through the longitudinal axis of the ship. In areas where the transverse profile of the arch is flattened, it is generally quite close to an arc of a circle or a conic section. However, it can be made up of two or more straight and/or curved segments that meet tangently and/or at an angle. Excluding the skirt, the ratio between the height of the arch and its width is low, generally less than 15%; excellent results are obtained with ratios of 2 to 6%. At the limit, this value can be zero, and the arch profile is then rectilinear, which simplifies construction but presents several disadvantages. In the areas of interest, the transverse profile in the form of a flattened arch can vary depending on its position. Apart from the connection with the bow and possibly the stern, it is preferable to maintain a constant or practically constant profile in these areas, as this facilitates construction and improves efficiency. However, a change in the width of the arch from the bow to the stern of the boat produces particular effects that may be desirable in certain applications. Furthermore, the multiple arch system illustrated in Figures 8a and 8b allows this construction to be extended to wide boats. Reinforcements 23 or 24, 25, which delimit all the sections, can act as keels or as the starting point for the stem, which then takes its usual form. However, instead of this usual form, the stem can be presented, as shown in Figure 10, in the form of a NACA air intake. In this case, the bow 29 is hollow and opens at the front with a vertically arranged window 20, 30, widening towards the rear into a flattened cell 31 ending at the height of a forward step 32, the rear opening of which is fitted with blades 33, similar to the blades 14. In this case, the bow 29 serves to recover the boundary layer, to decompress the bow wave, or, when the boat is planing, to contribute to the air "lubrication" of the hull 5. There is a forced dynamic supply of air and at the same time the braking due to the water being pushed back at the front is avoided. If we now refer to the propulsion unit, it has been represented in 27 as a motor. propeller, but, of course, it could be another system, notably a hydrojet, as illustrated in Figure 11. Such a hydrojet must also be suspended in a nacelle from a pylon, but above all include an ogive-shaped grid to prevent the suction of debris. In all cases, the propeller can be mounted on a vertically movable pylon, so as to ensure its immersion in the event of significant planing of the boat. Such planing can also be adjusted by adding a depth-adjustment flap as shown by the dashed line in Figure 2, in the form of a plane mounted pivoting around two horizontal axes in the skirts. To further improve the boat's planing on the water, without allowing the air ejected by the slots 14 to escape laterally, the skirts 14 and 15 can be supplemented by skids, possibly orientable as illustrated in figures 12 to 15: - in figure 12, these skids 39, 39' are horizontal perpendicular to the skirts, and supplemented by two vertical ribs 40, 40', kept submerged and maintaining the orientation of the boat; - In figures 13 and 14, these skids 41, 41 or 42, 42' are oblique, outwards or inwards respectively, and play the dual role of 39, 40 preceding: - In figure 15, the skirts 43, 43' are no longer vertical in line with the sides 1, 2 of the boat, but inclined, and possibly flared in line with the arch 17, and they are complemented by the skids 44, 44', inclined outwards so that the two frames 43, 44 and 43', 44' act as two mini-hulls of a mini-catamaran, gliding on the water and the air gap 45 trapped under the arch 17. In fact, the skirts can be formed by the outer edges of the arch 17 themselves, provided that that they be located in the aforementioned plane H. Although it is understood that the four components of the combination identified above are necessary and sufficient to benefit from the advantages of the invention, it is envisaged, while remaining within the scope of the invention, to replace one of these secondary components with an equivalent element for a specific purpose. Thus, Figure 16 illustrates a variant in which the nozzle formed by the particular construction of the rear of the boat is replaced by a platform 48 comprising adjustable vanes 49 in which pyrotechnic boosters can be housed, intended to trigger an instantaneous start of the boat, particularly for military purposes. If we return to the construction and arrangement of the propeller 27, while it is shown in figure 17 mounted in a nacelle supported by a vertical pylon 28, figures 18 and 22 illustrate a series of variants that can be applied depending on the designation of the boat. Thus, in figure 18, the propeller 50 is mounted on a horizontal supporting plane 51, while in figure 19, the propeller 52 is supported by a vertical pylon 53 on which are also mounted fins 54, which can themselves be adjustable, or have variable geometry, retracting. high speed by taking up the position shown in the dashed line 54', of smaller surface area, and also acting as cavitation plates for the propeller 55. Similarly, as in figure 20, the pylon 56 can support several stages of fins 57. These fins are adjustable in incidence to obtain lifting or drag effects allowing the trim of the boat to be modified. In figures 21, 22, a double propulsion system 58, 59 is shown, mounted on each side of the hull and pivoting around axes 60 so that they can be retracted in case of grounding (complete drying out), which also corresponds to a military application of this boat. Figures 2, 3a, and 23t finally depict; propulsion systems consisting of hydrojets 61 housed in the lateral keels and ejecting their water above the waterline; these ejections can be individual (Fig. 23a) or grouped (Fig. 231). Similarly, according to another variant, one or more propeller-driven propulsion systems can be arranged at the stern, preferably with propellers adapted for operation in emulsified water. As explained at the beginning of this description, this characteristic combination of boat components is the source of still unsurpassed performance. The following concrete examples illustrate this performance. Example 1: An experimental launch was built according to the invention. It was subjected to comparative tests eliminating one or more of the first four means of the invention. The numerical data of this launch are as follows: ;25 - power 110 hp: (Z DRIVE BMVÏ 130 propulsion), ;- construction in fiberglass-reinforced polyester, ;- overall length: 8.40 meters, ;- overall length at waterline: 7.60 meters, 30 - beam: 2.0 meters, ;- draft at rest: 0.160 meters, ;- weight in running order with two people on board: 1.8 tons. ;The test consists of measuring the speeds in both directions over a course between buoys of approximately 2 km; on calm seas and averaging the results. ;The speed of the launch incorporating the first four means of the invention, which reaches 28 knots, drops to 22 knots when the intake of air under the hull is prevented by blocking the hollow frames. A classic high-performance V-hull (Vë) speedboat of the same dimensions and displacement, but without these modifications, reaches 26 knots, but with an installed power of 260 hp. This double test highlights: 1. The complete set of modifications according to the invention allows for a power gain greater than t2. 2. Air intake is the source of a significant efficiency gain, but insufficient on its own. Example 2: Comparative tests were carried out on various high-performance fast boats, all results being adjusted by a coefficient corresponding to the power required to bring a hull with a displacement of one ton to a speed of 30 knots, using official formulas, notably that of the French Admiralty. If we analyze these results using a coefficient of 100 for the boat according to the invention, we find that all the other hulls have higher coefficients, namely: 145, 198, 212, 393, and 870. The power index of the boat according to the invention was therefore not achieved with any of the other boats subjected to the tests, which demonstrates its absolute superiority, taking into account all other economic variables. Of course, other factors of a technical nature must also be considered: the boats according to the invention combine the advantages of monohulls, particularly with regard to robustness and ease of construction, as well as those of catamarans for their transverse stability. Furthermore, the air gap dampens the shocks of the water, while the optional bow thrust provides very high longitudinal stability. This results in very high stability even at high speed, which improves crew comfort and the deployment of weapons and/or various equipment such as fishing gear. Since the boats according to the invention can have a much greater beam than conventional vessels without compromising their performance, they can have a very large deck, which, combined with their very high stability, will allow helicopters to land on shorter boats.

Claims (21)

REVEND ICAT IONS. 1. Fast motorboat, characterized in that it has a hull, the bottom of which has, over most of its length, a transverse profile in the form of a flattened vault, this bottom having over most of its length a series of steps, most of these steps having on their rear face one or more openings possibly subdivided, each of which communicates in a watertight manner with atmospheric air, the two sides of the boat being extended towards the stern by a skirt whose height is substantially equal to that of the steps, and substantially parallel to each other: . 2. Boat according to claim 1, characterized in that each open step communicates with atmospheric air by means of a hollow frame and/or by means of tubes. 3. Boat according to claims 1 and 2, characterized in that said crushed vault has a substantially constant profile over the entire length of the hull. 4. Xateau according to claims 1 to 3, characterized in that said cross profile is subdivided into two or more arches, joined by reinforcements constantly above the outer lower part. 5. Boat according to any one of claims 1 to 4, characterized in that the longitudinal profile of said vault is substantially rectilinear. 6. Boat according to claim 1, characterized in that said steps are created by vertical step-outs in the longitudinal profile of the boat, said opening being created by this step-out. 7. Boat according to claims 1 and 6, characterized in that said step-outs are rectilinear along a plane perpendicular to the axis of the boat or have another shape or orientation, provided that it is symmetrical to the axis of the platform. -18 - 8. Eateau according to one of claims 6 and 7, characterized in that said opening occupies only a fraction of the transverse dimension of the step and can be further divided into several separate openings. 5 9. Eating according to any one of claims 6 to 8, characterized in that said opening and/or said step can be adjustable, such adjustment being able to extend to total closure. 10. Boat according to any one of claims 6 to 9, characterized in that guide vanes are mounted in said openings, their orientation being adjustable. 11. Boat according to claim 1, characterized in that in the rear part of the boat the area 15 rear of the vault can be raised or inclined upwards over a certain part of its length, following a straight longitudinal profile, broken line and/or curvilinear, the vault, in the corresponding portion, can retain its previous profile or present a different profile depending on the effects sought. 12. Boat according to claim 11, characterized in that a step determines the origin of said portion of the rear area. 13. Boat according to claims 11 and 12, ca-25 characterized in that the height of the skirts is raised totally or in part to compensate for the raising of this portion of the rear area and to act as daggerboards and possibly include a rudder on each side. 14. Boat according to claim 1, characterized in that the propulsion device is mounted in the forward areas of the boat and optionally in an oriental manner. 15. Boat according to claim 10, characterized in that said at the s are closer together towards the ex- 35 outside than towards the inside. 19 16. Boat according to at least one of the preceding claims" characterized in that the skirts terminate their lower longitudinal twists in whole or in part by pads facilitating the planing of the hull. 17. Boat according to claim 16, characterized in that these skids are horizontal, ollical inwards, ollical outwards, and/or in line with the arch. 18. Boat according to at least one of the preceding claims, characterized in that its bow is of the N.A.C.A. type or similar and opens onto a bow wave recovery cell and touches at the rear by an opening for the ejection of the sucked air and water. 19. Boat according to claim 14, characterized in that the propulsion unit is mounted on a vertical pylon, optionally movable vertically, optionally equipped with one or more fins optionally with variable incidence and/or geometry, or on a horizontal plane. 20. Boat according to any one of claims 14 and 19, characterized in that it comprises two or more lateral thrusters located on each side of the hull and retractable in case of grounding. L 21. Boat according to claim 1, characterized in that it comprises at the stern at least one ejection propulsion device located above the waterline, and/or pyrotechnic tosters.