EP0042584B1 - Boat hull, especially for sailing-ships and yachts - Google Patents

Description

The invention relates to a hull according to the preamble of claim 1.

In known hulls of this type (GB-PS 285 572) with a shape mimicking the wing profile of an aircraft, the profile extends continuously over the entire width of the boat, the transition from the bottom of the boat to the two sides of the boat being designed in steps, i. i.e., despite their wing-like profiling, such hulls run essentially on the principle of conventional hulls, i. that is, according to the displacement principle, at least in the middle and lower speed range of the hull there is no buoyancy. This only forms at higher speeds.

In order to create a buoyancy effect, it is necessary to put greater strain on the hull at the stern as the voyage increases, in such a way that the profile of the hull forms against the water surface. Such a positioning of the hull brings with it an increase in the resistance against which the boat runs; in addition, the boat is relatively unstable in terms of sliding speed and is very difficult to maneuver.

Based on this, the object of the invention is to design a boat hull so that the actual gliding process begins very early; when driving - even at low speed - the forces acting on the underside of the boat should raise the hull and thereby bring about the gliding without requiring an angular adjustment of the hull as a whole. With the task aspect of avoiding a hull position, the present invention turns away from the prior art.

The features according to the characterizing part of patent claim 1 serve to solve the above object.

Such a design of the hull offers the advantage that the so-called "glide travel" is achieved even at low speeds without turning the hull. Here, the direction of flow of the water with respect to the hull in the area of the stern is essentially parallel to the lower surface of the boat. The angle of attack is practically zero at this point, which means a corresponding reduction in the resistance. Of particular advantage is the possibility of a channel-like guidance of the outflowing water in the area of the stern, which can be achieved by arranging and dimensioning adjacent profiles and the angle of attack of the tendons, in such a way that the resultant force results in a lift, even at low speeds, which contributes to the achievement of gliding.

With regard to the prior art, reference is also made to DE-PS 687 340. This discloses a watercraft, the fore-aisle of which is built in the underwater part in the form of a displacement frame with bulging bottom and side walls that do not have a dynamic buoyancy against the direction of travel, while the stern of the ship is designed in the form of a floating boat with the butts pulled down. The stern of the ship should lie entirely in the current influenced by the fore ship, the gliding surfaces not being hit directly by the waves. The sliding surface of the stern is supposed to have such a large transverse curvature or incline against the lateral direction of movement of the flow generated by the fore that the flow is deflected so far that it leaves the boat in parallel streamlines (claims 1 and 2 of DE-PS 687 340) . As can be seen, the sliding surface is provided in the longitudinal section with a curvature which extends in a longitudinal plane in the rear area up to a tangential position to the water level and beyond.

According to a further development, a gradation should even be provided between the fore and aft.

This well-known watercraft is a typical hull built in a transverse frame construction (V-frame in the front, round frame in the stern). Lateral sliding surfaces are assigned to the front displacement part. However, these sliding surfaces in no way have a profile in the longitudinal direction corresponding to the underside of an asymmetrically constructed aircraft wing. This publication does not address this possibility in any way. The sliding surfaces are also heavily adjusted, so that the tail dives very deep in the idle state. This known watercraft was already based on the task of reducing the resistance and at the same time improving the behavior in rough seas. Although this document has been known for decades, it has not been able to contribute to a satisfactory solution to the problem on which the present invention is based.

The US-PS 3 930 455 (Bremer) shows a modification of a V-motor boat sliding hull, in which the sliding properties are to be improved in that a combination of a three-hull boat with a V-sliding hull takes place in such a way that there is a monohull boat in the swimming state and a triple hull in gliding condition. When the glide speed is reached, the boat only runs on the three parallel, water-ski-like gliding surfaces, between which there are channels. The profile data of the longitudinal sections of each sliding surface are the same across the width of each sliding surface. There is no sweeping and there is no continuous shortening of the profile lengths from the inside to the outside. Due to their inclination to the water surface, the longitudinal cuts of the two outer sliding surfaces and the difference therefrom result nowhere a tangential course. Hulls with a diving stern and inclined gliding surfaces are also not suitable as sailing boat hulls, because with this configuration there are high resistances at low speeds (displacement) and during semi-gliding. The reduction in resistance that can be achieved with the water-ski-like sliding surfaces is inferior to the reduction in resistance by preventing the boat floor from being tilted.

Despite extensive efforts to improve the sliding properties of boat bodies, in particular for sailing dinghies and yachts, and the known imitation of the wing profile of an aircraft in boat bodies, the advantageous combination of features according to the present invention has not been suggested by the entire prior art. Even taking into account the wetting of the hull and the resulting water resistance, the combination of features according to the present invention results in a considerable reduction in resistance overall, because the special shape of the boat prevents the occurrence of the wave resistance from the outset. Nevertheless, the hull is not tilted as a whole, but the hull assumes the same and stable trim position in the static and dynamic state.

The design of the hull in the form of the underside of an airfoil offers the advantage that the so-called «glide travel is achieved at low speeds. Here, the direction of flow of the water with respect to the hull runs in the area of the stern parallel to the lower surface of the boat, the angle of attack is practically zero at this point, which means a corresponding reduction in resistance.

Advantageous refinements and developments are listed in further patent claims.

The invention is explained below using exemplary embodiments with reference to the accompanying drawings.

• FIG. 1 is an aircraft wing profile, the design of which underneath the chord corresponds to that of the hull according to the invention, at least in a longitudinal zone;
• Figures 2 and 3 are side views of boat hulls according to the invention, in particular for sailing dinghies;
• Figure 4 shows the floor plan associated with the construction of Figure 3; the scow shape shown here, in which the tendon front ends lie in a common transverse plane, corresponds to the prior art in this figure and does not show the sweep according to the present invention;
• Figure 5 is a sectional view of line 5-5 in Figure 4;
• FIG. 6 shows differently designed hulls on the left and right sides in the area of vertical cross sections;
• Figure 7 shows left and right side sectional views of other hulls according to the invention;
• Figure 8 shows characteristics for seven different hulls according to the invention;
• FIG. 9 shows a half of the hull illustrated in FIG. 2, seen in a bottom view, the relative assignment of the characteristic curves being illustrated;
• Figure 10 is a sectional view of line 10-10 in Figure 9;
• FIG. 11 is a representation corresponding to FIG. 9 of a further hull according to the invention;

An asymmetrical profile of an aircraft wing is shown in FIG. H. a profile which has different Y values above the chord S than below the chord S. Here, the chord S is the straight line which connects the front end of the profile to the rear end thereof.

2 shows a side view of the hull of a sailing dinghy or yacht. The underside of this hull according to the invention is shaped so that buoyancy-generating forces arise during the trip without the boat having to be turned. The center of gravity of the boat is located so that the stern 10 of the unloaded boat does not reach below the horizontal plane 12 of the water level. In at least one longitudinal zone lying below the horizontal plane 12, the underside of the hull has the same vertical longitudinal section profile 14, which also has the underside of the aircraft wing in FIG. 1. This profile extends tangentially to the horizontal plane 10 of the water level in the area 16, while the chord S of the wing profile lies in the horizontal plane 12 of the water level. As a result, the angle of attack of the underside of the boat in area 16 is zero or almost zero. In this way, there is very little drag at all speeds, since the boat essentially maintains the prescribed relative position at all speeds. The hull shown in Fig. 2 is already sliding at very low speeds. If this is the case, the hull is essentially in its entire length in the region of half the wavelength of the bow wave generated, the water in region 16 flowing essentially parallel to the underside of the boat. The apex 18 of the curved underside of the hull, that is the point at which the dimension Y has the maximum value, is closer to the bow than at the stern. In particular, the distance of the apex 18 from the front end 20 of the sight S can be less than 40% of the total length of the tendon. This results in a particularly favorable flow in the range of driving speeds up to 40 knots.

In the exemplary embodiment shown in FIG. 2, Y becomes zero at approximately point 22. There, the longitudinal section profile 14 reaches the tendon S tangential. Between points 10 and 22, the underside of the boat runs parallel to the horizontal plane 12. The distance between points 10 and 22 can be 5% -25% of the hull or the length of the tendon S, which extends from the stern 10 to the front end 20 of the longitudinal section profile 14 extends. But there is also the possibility to let the rear 10 coincide with the point 22. The shape shown in FIG. 2, in which the stern 10 is at a considerable distance behind the point 22, offers particular advantages for higher speed ranges of more than 15-20 knots. These advantages are that the tendon S maintains its position parallel to the horizontal plane 12 and does not require a larger angle of attack, which would lead to greater resistance.

Towards the front, the vertical longitudinal section profile of the underside of the hull is continued up to the point over the horizontal plane 12 of the water with unchanged or only slightly changed curvature. The further course depends on the shape of the bow, for which different shapes are indicated by dashed lines in FIG.

Fig. 1 shows in dashed lines that the vertical longitudinal section profile 14 of the underside is continued forward with unchanged or only slightly changed curvature. This results in an airfoil profile without a nose radius. However, a profile with a nose radius rounded at the front can also be used, as is also shown at 26 in FIG.

5 shows on the right that the side wall of the hull has rounded frames 32 there. 5 shows a side wall on the left with simple oblique frames 34 or bent frames 36.

However, this shape, shown in FIG. 4, of the underside of the hull lying below the water level is not the most suitable for all types of boats, since the boats move more or less about a horizontal central axis. Through this movement, the buoyancy-generating profile surface that is touched by the water is changed more or less symmetrically or asymmetrically. The influence of the side wall must be taken into account, which is no longer attributable to the longitudinal zone of the underside of the hull, as defined in claim 1. In order to obtain more precise, more precisely defined wing arrangements in relation to the midships plane, in which the chord plane intersects the water line at a predetermined angle, the configuration shown in FIG. 1 is recommended. The left half of this figure shows a vertical cross section through a hull, in which the longitudinal zone of the underside of the hull specified in claim 1 is limited to a narrow zone 40 which receives the vertical longitudinal central plane 38. It is therefore only for this zone 40 that the chord of the wing profile lies in the horizontal plane 12. The longitudinal sectional profiles of the underside of the hull extending at a greater distance from the longitudinal central plane 38 have the same shape as the longitudinal sectional profile in zone 40, but they have different heights. This is because their tendons lie in surfaces 42 which rise towards the hull sides 44. In the embodiments shown on the right and left in FIG. 6, the surfaces 42 represent planes. The hull sides 44 can have straight frames, as shown in FIG. 6 on the left, or curved frames 46, as in FIG. 6 on the right shown.

In Fig. 7 two embodiments are shown in which the surfaces 42 are not flat, but kinked. The kink lines 48 form straight lines that run parallel to the vertical longitudinal center plane 38 of the hull.

Further entangled, multi-kinked wing arrangements are given in Fig.8. The characteristic curves shown there represent the areas 42 in which the tendons S of the vertical longitudinal section profile of the underside of the hull lie. Line A is kinked twice, namely at 48 and 50. Line B is also kinked twice and runs from the vertical longitudinal median plane 38 first weakly and then more upwards and outside of the kink line 50 either upwards or downwards. Line C shows a surface 42 which initially runs slightly downwards from the vertical longitudinal center plane 38 and upwards outside the fold line 48. Line D is similar to line C, but has a second fold line 50 and can take three different directions beyond this fold line.

Embodiments are shown on the right-hand side of the figure, in which the surface 42, in which the tendons S of the wing profiles of the underside of the boat are located, is curved. These curved surfaces 42 have straight surface lines which run parallel to the vertical longitudinal center plane 38 of the hull.

For the sake of simplicity, these curved surfaces 42 are shown without reference to the horizontal plane 12 of the water level. The relative position of the water level to the hull depends solely on the volume, the heel angle, the stability, the desired wetted surface and the desired glide angle. In principle, however, these factors do not change the design.

FIG. 2 shows the underside of the hull illustrated in FIG. 2, the supporting surfaces of which are swept to the rear. The vertical longitudinal median plane 38 is indicated in FIG. 9 as a straight line, below which the longitudinal section profile 14 is drawn. The apex 18 is located there in the perpendicular transverse plane 52.

In the longitudinal plane 54, which runs parallel to the plane 38, the underside of the hull lying below the water level has the longitudinal section profile 56, which not only has a much shorter chord S than the longitudinal section profile 14, but also a significantly smaller maximum value of Y at the apex 58 , which is located in the transverse plane 60, which is located further to the stern than the transverse plane 52. In the vertical longitudinal plane 62, which extends parallel to the longitudinal planes 54 and 38, the underside of the hull lying below the water level has an even shorter wing profile with the Vertex 64, at which Y max is located, which is even smaller than that at vertex 58. The vertex 64 also lies in a transverse plane 66, which is even closer to the stern than transverse plane 60.

The three vertices 18, 58 and 64 lie in a vertical plane 51, which includes the angle 52 with the transverse plane 52.

Above the horizontal plane 12 of the water level, the hull has a rear 70 at the stern, which can be inclined to the horizontal plane 12. It can also be inclined to the vertical longitudinal center plane 38, as indicated by the two angles <pH in FIG. 9.

An important value for the sweeping of the profile is the angle <p, which the surfaces 51 and 52 enclose.

While in the embodiment of FIG. 9 the surface 51 is a plane, there is also the possibility of making it run in a bent manner. This means that the three vertices 18, 58 and 64 have a curved connecting line. If the profiles in the three longitudinal planes 38, 54 and 62 have the same ratio of length to thickness, and the length of their tendons S decreases with increasing distance from the central plane 38, then the absolute values of X and Y become smaller towards the side of the boat . It also follows that if the tendons S are in the same horizontal plane, the bottom of the boat rises outwards. This effect can be increased in that the tendons S are arranged in the planes 42 of FIGS. 6-8 instead of at the same altitude.

As already described, the rear side 70 can be designed differently. The angle 9H can be designed to be positive, negative or zero.

If the plane 51 runs in a curve, so that the profile length X decreases unevenly towards the outside, then the bottom of the boat also forms a curved surface in the vertical direction when viewed from the horizontal plane. Even at smaller angles ϕ, the bottom of the boat is twisted, since, depending on the selected profile conditions, the size Y can increase in size in the direction of the side area, as shown by line 80 in FIG. 10. If this is to be avoided, a weaker sweep or delta wing construction is indicated. However, the twist can also be generated by also twisting the chord plane 42 viewed from the side. By appropriately selecting a positive or negative angle of attack of the chord plane on the outside, the twisting of the boat bottom can also be regulated with a fixed angle ϕ. These options are of particular interest for gliding boats and multihulls.

• (1) Die Profilsehnen liegen in einer mittleren Zone in der Horizontalebene des Wasserspiegels aber weiter außen bilden sie einen positiven oder negativen Winkel mit der Horizontalebene.
• (2) In einer mittleren Zone haben die Profilsehnen einen positiven oder negativen Winkel zur Horizontalebene und weiter außen verlaufen die Sehnen in der Horizontalebene des Wasserspiegels oder parallel dazu.

In the embodiment shown in FIGS. 3-5, not only is the chord S of the wing profile in the vertical longitudinal central plane 38, but also the chords of the wing profiles in the planes running parallel thereto, e.g. B. in levels 28 and 30 in the horizontal plane 12 of the water level. Deviating from this shape of the hull there is a distortion of the chord plane 42 in that the underside of the hull has the shape specified in claim 1 only in lateral longitudinal zones, in which the chord of the bottom profile lies in the horizontal plane of the water level, while between these lateral longitudinal zones in a middle zone the tendons have a positive or negative angle of attack, i.e. they are not in the horizontal plane of the water level. Smooth transitions between the following options can be carried out:

• (1) The chords lie in a central zone in the horizontal plane of the water level, but further out they form a positive or negative angle with the horizontal plane.
• (2) In a middle zone the chords have a positive or negative angle to the horizontal plane and further out the chords run in the horizontal plane of the water level or parallel to it.

Furthermore, there is the possibility to position all chords more or less to the waterline level positively as well as negatively.

In the shape of the hull shown in FIG. 11, the chord lengths of the wing profiles of the underside of the hull decrease from the inside to the outside to zero. The front ends of the wing profiles lie on a vertical plane 74 which intersects plane 51 in the rear 70. The further outside the vertical longitudinal section profile to the underside of the hull, the smaller the distance of the front end 20 of this profile from the apex 18 or 54.

Claims (16)

1. A boat hull, particularly for sailing skiffs and yachts whose underside has the profile of an aircraft wing at at least one longitudinal section of the underside, the center of gravity being positioned in such a way that the stern of the non- loaded boat does not extend considerably below the horizontal plane of the water level, the chord of the profile lying substantially in the horizontal plane of the water level, characterized in that for avoiding an angle of attack of the boat hull during the ride the vertical longitudinal section profile (4) toward the stern extends substantially tangential with respect to the horizontal plane (12) of the water level within at least one longitudinal zone below the horizontal plane (12) of the water level, the area (16) of tangential approach of the longitudinal sectional profile (14) to the stern of the boat hull having a length of 5-25 % of the over-all length of the boat hull, further characterized in that the vertex (18, 58, 64) of the profile with respect to the bow end of the chord is within a range (16) of essentially less than 14% of the entire chord length, the starting points of adjacent profiles being positioned on an arrow-shaped line over the width of the boat hull.

2. Boat hull according to claim 1, characterized in that the cord in the outer region of the hull is inclined relative to the chords of the intermediate region of the hull.

3. Boat hull according to claim 1 or 2, characterized in that the vertical longitudinal sectional profile (14) is continued forwardly to above the water level plane with nearly unchanged curvature so as to form the bow of the boat hull.

4. Boat hull according to claim 1, characterized in that both the chord (S) of the longitudinal sectional profile (14) of the vertical longitudinal center plane (38) and the chord (S) of the longitudinal sectional profiles of the planes (28, 30) parallel with respect to the foregoing center plane are extending within the horizontal plane of the water level.

5. Boat hull according to claim 1, characterized in that only the chord (S) within the vertical longitudinal center plane (38) or the chord (S) closely adjacent thereto of the wing-like hull profile are within the horizontal plane (12) of the water level, whereas the chord (S) of the outer longitudinal sectional profiles are located at different elevations.

6. Boat hull according to claim 5, characterized in that the chord (S) of the outer longitudinal sectional profiles are located in planes (42) which rise over the horizontal plane of the water level or slope.

7. Boat hull according to claim 5 or 6, characterized in that the planes (42) are bent, the bending lines (48, 50) forming streight lines parallel to the vertical longitudinal center plane (38) of the boat hull.

8. Boat hull according to claim 5 or 6, characterized in that the planes (42) are curved.

9. Boat hull according to claim 5 or 6, characterized in that the vertices (18, 58, 64) of the wing profiles located at different distances from the vertical longitudinal center pane (38) of the boat hull are on a streight line (51) including an acute angle (ϕ) with respect to a vertical transverse plane (52) of the boat hull.

10. Boat hull according to one of the claims 1-9, characterized in that the edge of stern (70) is forming an angle (tp_n) in relation to the plane which is at right angles to the vertical longitudinal center plane.

11. Boat hull according to claim 10, characterized in that the boat bottom at the stern (70) has an underside curved in the vertical direction as viewed from the horizontal plane.

12. Boat hull according to claim 11, characterized in that the boat bottom at the stern has a complex curvature with which depending on the profile conditions selected the hight of the wing profile can increase in magnitude towards the lateral area.

13. Boat hull according to claim 1, characterized in that the underside of the lateral areas has the shape claimed but the chord a central zone there between have a positive or negative angle of attack.

14. Boat hull according to claim 1, characterized in that its underside in a central zone has the shape claimed, but the chord in the lateral zones have a positive or negative angle of attack.

Images