EP0760773A1

EP0760773A1 - Hull for water-borne vessels, especially sailing boats and surfboards

Info

Publication number: EP0760773A1
Application number: EP94923575A
Authority: EP
Inventors: Klaus-Dieter Lehmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-07-30
Filing date: 1993-02-02
Publication date: 1997-03-12
Also published as: DE4125187C2; DE4125187A1; WO1994018063A1

Abstract

In order to reduce the sailing resistance of a ship's or boat's hull with good dimensional stability, said hull is designed in such a way that it consists of a smooth underwater projection (2) above which there is a broader hull section (1), the displacement volume of which increases sternwards in such a way that it offsets or even exceeds the reduction in buoyancy volume of the underwater projection (2) which becomes smaller towards the stern.

Description

"Hull for watercraft, especially sailboats and surfboards"

description

Hull for watercraft, in particular sailing boats and surfboards. The invention relates to a ship or boat hull according to the preamble of claim 1.

Several fuselage constructions are already known in which one or more slender projections are arranged under a wider fuselage part. See the published patent application of the German Patent Office DE 3639175 A1 from 26.05.88, patent specification of the Reichspatentamt No. 704991 from April 15, 1941, United States Patent from July 09, 1974, No. 3.822, 661 and European Patent Application No. 0 298 050 dated June 28, 1988. The problem with these fuselages is that the displacement of the fuselage, in particular the projection, decreases from a certain point in the longitudinal direction. The consequence of this is that the water displaced and accelerated transversely by the fore when the ship is cruising at high speed does not flow back quickly enough, and a vacuum zone is formed in the rear area of the hull, which increases resistance or causes the stern to sag. This negative effect can be exacerbated by the bulging shape of the underwater ship in the rear area. With some constructions, there are other negative effects. In the case of some of the known constructions, the center of gravity of the buoyancy in the case of heeling also does not shift particularly from the center, so that they are not suitable for sailing, ie they are too "rank".

REPLACEMENT LEAF The invention is based on the object of designing a hull so that it dips relatively softly into the water with high dimensional stability against heeling, even at sea, and to reduce the resistance to an absolute minimum the displacement performance, ie the displacement work while driving, over almost the entire hull length is distributed in order to largely avoid the formation of resistance-increasing negative pressure zones (suction zones) in the rear area and thereby to reduce to a minimum the sag of the tail, which is the result of excessive displacement.

The object is achieved by the characterizing features of claim 1.

The advantages achieved by the invention consist in particular in reducing the driving resistance in order to save propulsion energy or to achieve higher speeds with the same expenditure of energy. Furthermore, there is a gain in interior volume due to the wide, protruding stern of the ship or boat. These advantages can be used in commercial shipping as well as in sports or leisure shipping. Further features and advantages of the invention emerge from the following drawings.

Show it

Fig. 1 shows a wide fuselage (1) with a slim projection (2), the lower edge (4) from the point of highest displacement at the same depth further to the rear, while its side surfaces (3) converge in a line at the back.

2 shows the cracks of the frames §), (4) and (5)

Fig. 3 shows an embodiment of a fuselage (1) with a slim projection (2), the side lines (3) diverge further apart from the point of greatest displacement to the rear, while the lower edge (4) runs backwards upwards and in the fuselage (1) .

4 again shows the cracks of the frames (2), 3), (4) and (jj) from FIG. 3 for clarification.

In Figure 1 it can be seen that the theoretical transition line (5) between the wide upper fuselage part (1) and the lower slim projection (2) is just before the

REPLACEMENT LEAF The point of the highest displacement or the largest cross section of the slim projection (2) goes into the area below the water line WL and runs deeper and deeper as the length increases. In view Z of FIG. 1, this results in a course of the water line WL on the wider hull (1). It can be seen that as the cross-section of the slim projection (2) decreases, the water-displacing cross-section of the upper fuselage part (1) increases, and this to the same extent or more. Only at the end of the upper part of the hull (1) is there a slight decrease in displacement in this example, in order to facilitate the breaking of the water flow at the rear edge of the ship even at relatively low speeds ϊ). Furthermore, with this construction the fuselage will lift out a bit more at the front and sag slightly at the back, so that there will no longer be any negative pressure in the area of the frame (jδ) to the frame. This fuselage carries much more at the back than (1) and is particularly suitable for heeling. Then he lies in the water with a sliding surface. In Figure 2, the lines of the frames 3), (Z) and ($) are shown. To the right of the central axis of the fuselage, the loss of cross-section (5a) of the lower, slim projection (2) between frame (5) and) can be seen, while in the area of the upper fuselage part (1) there is an increase in cross-section (5b). To the left of the central axis, the cross-sectional loss (4a) can be seen in the lower area between the frame (4) and (§), while another cross-sectional gain (4b) can be seen at the top.

The displacement of the "water in the way" is now done in the following way:

The lower projection (2) displaces the water with extremely little power due to its pointed shape and its associated extremely small volume increase in the longitudinal direction. Most of the water flows along the slim hull and experiences only low lateral acceleration forces or transverse speeds, so that in principle only a kind of pre-acceleration takes place. The water pre-accelerated in this way with relatively little effort makes it easier for the part that is becoming increasingly voluminous to do the displacement work due to a lower back pressure, which also reduces the actual frictional forces on the surface. The displacement of the upper part of the hull (1), which begins approximately from frame @ and increases towards the rear, not only causes the displacement line to extend almost over the entire length of the ship, but at the same time also prevents the suction on the side walls, which increases with increasing speed ( 3) of the lower projection (2). Because the water is also in the back

REPLACEMENT LEAF the broad hull (1) still experiences slight lateral acceleration forces, the wave formation is strongly shifted to the rear, and the "trough" in the water between the waves practically only forms behind the ship, which still breaks off the water flow at the transom on the line ζ) relieved. Due to its acute angle and the distribution of the displacement power over the entire length, this type of displacement corresponds in principle to that of a slim ship that is about twice as long, whereby the frictional losses of the theoretically longer ship are not as important as those at the stern of such a ship again training suction forces.

FIG. 3 shows an example in which the inevitable loss of volume of the slim projection (2) is brought about by the lower edge (4) running upwards. To partially compensate for the loss of volume from below, the slender protrusion is widened at the same time as it continues to the rear at the transition to the upper part of the fuselage (1) until, in its entirety, it merges harmoniously into the upper fuselage. For this variant, too, it is shown in FIG. 4 how the area or volume shrinkage of the lower projection (2) is largely compensated or superimposed by increasing the volume of the upper fuselage part. This can be seen again from the hatched areas (4a) and (4b) as from the areas (5a) and (5b). To illustrate the harmonic transition of the lower projection (2) into the upper part of the fuselage (1), the crack of the frame is shown here.

With respect to the volume increases and decreases of the lower projection (2) other line courses are of course also possible, e.g. pulling up the lower edge (4) to approximately half the height shown in FIG. 1 or similar; it is important, however, that the displacement volume, which becomes less at the bottom, is approximately compensated for or increased by the upper fuselage part (1).

REPLACEMENT LEAF

Claims

"Hull for watercraft, especially sailboats and surfboards" claims

1.Hull for watercraft, in particular sailboats and surfboards, in which at least one longitudinally extending, buoyant, slender projection below the waterline is arranged below a wide part of the hull, which decreases in size forwards and backwards, characterized in that wide hull part (1) in the rear area lying below the waterline WL, in which the slender projection (2) decreases, increases by at least approximately as much in cross-sectional area as the slender projection (2) decreases in cross-sectional area.

2. Fuselage according to Claim 1, characterized in that the cross-sectional area lying below the waterline from the front to the rear remains at least approximately the same size up to the transom.

3. Hull according to claim 1, characterized in that from the front to the rear, at least to the rear end of the slim projection, the cross-sectional area lying below the water line increases continuously.

REPLACEMENT LEAF

4. Rumf according to claim 1, characterized in that the projection widens and flattens in the rear region.

5. Fuselage according to claim 1, characterized in that the projection has an outlet for a screw shaft at its rear end.

6. Fuselage according to claim 1, characterized in that the slim projection merges into an arc in the wider part of the fuselage.

7. Hull according to claim 1, characterized in that the hull has at its rear end a transom which extends below the waterline and is bounded there by a tear-off edge.

8. Hull according to claim 7, characterized in that the transom ends 5 to 15 cm, in particular 8 to 10 cm below the water line.

REPLACEMENT LEAF