Hull configuration

Description

[0001] The invention relates to' a displacement-type hull configuration which makes it possible to improve a vessel's deadweight tonnage, transverse stability, navigational and sailing properties and to reduce stresses on the hull beam whether the vessel is sailing in quiet water or into the waves.

[0002] At given main dimensions of length, breadth and depth to the design waterline, conventional hull configurations can obtain greater deadweight tonnage by increasing the roundness of the underwater portion of the hull, thereby increasing the total displacement.

[0003] To improve the transverse stability of a conventionally formed hull, expressed as a higher initial metacenter, the breadth of the hull can be increased to obtain a greater moment of inertia at the waterline, optionally also raising the volumetric center of gravity of the underwater hull.

[0004] However, changes of this nature (increasing roundness and breadth), as demands for transverse stability and speed increase, will eventually result in an unacceptable increase in a conventional vessel's resistance to propulsion in quiet waters as well as in heavy waves.

[0005] To improve the seagoing properties of a conventional hull configuration, expressed as the vessel's angular movements about a transverse axis (pitching), vertical movements (heave) and the amount of increase in propulsion resistance compared to the resistance in quiet seas, one seeks to alter the vessel's natural frequency of pitching and heaving so that this frequency insofar as possible does not coincide with the frequency of the wave lengths which the vessel encounters.

[0006] In the case of conventional hull designs, structural alterations result in only slight improvements in the seagoing properties of the vessel, and extreme pitching and heaving movements and a great increase in the resistance to propulsion will occur when the ship is sailing into the waves when the prevailing wave length is approximately equal to the ship's length at the waterline.

[0007] Depending on the type of vessel and its rate of speed, such synchronous movements always make it necessary for a conventional ship to reduce speed or alter course in relation to the waves, thereby altering the cycles of encounter with the waves so that the wave period does not coincide with the natural frequency of the vessel's pitching and heaving.

[0008] Conventional hull configurations having an approximately rectangular displacement distribution will be subjected, as a function of increasing size, to bending and shear stresses which necessitate very large dimension materials and in special cases also restrict the distribution of cargo and/or ballast.

[0009] The present invention is defined in claim 1. In accordance with the present invention, the deadweight tonnage, transverse stability, seagoing properties and the magnitude of tolerable bending and shear stresses on the hull beam can all be improved without incurring the above drawbacks. The invention permits the hull to be made with rounder lines than conventional hull configurations, expressed by the term for leanness of line L/V^1/3, where L is the length of the hull at the design waterline corresponding to the depth T to the summer freeboard and V is the displacement volume of the hull at the design waterline, and where LN1¹³ can be about 3 or greater than 3 without increasing the specific resistance to propulsion compared to conventional hull configurations, while at the same time the hull breadth B can be increased such that the L/B ratio can be about 2 or greater than 2, where B is the maximum breadth of the hull at the design waterline, whereby the height of the metacenter of the hull can be more than doubled in relation to conventional hull configurations of the same length.

[0010] At the critical wave length/hull length ratio for conventional hull configurations sailing into the waves,-the seagoing properties of the hull configuration of the invention are improved, such that the hull's pitching and heaving movements are reduced compared to the movements of conventional hulls traveling at the same rate of speed, and these movements are also retarded such that the improved hull does not exhibit correspondingly large movements until the wave length/hull length ratio is more than twice as large, while at the same time the improved hull's resistance to propulsion is reduced to a similar degree.

[0011] According to a preferred embodiment of the invention, the displacement distribution in the longitudinal direction approximates a Rayleigh wave which with normal distribution of cargo will result in a reduction of the longitudinal moment of bending on the hull beam of around 50 % compared to conventional hulls. To obtain the abovesaid improvements, the hull configuration according to the invention must be formed with squarely cut off, approximately harmonic sinusoidal waterlines (dwl, 1, 2, 3) with extremity or stationary, points at the ends of the hull fore and aft, while at the same time the base lines of the waterlines (O_dli, 0₁, 0₂, 0₃) from the design waterline (dwl) and at increasing depths from this, gradually are displaced in the direction of forward propulsion and shortened so that an approximately oblique surface (s), which may be straight or approximately sinusoidal in longitudinal cross section and with extremity points around L/2 and at the hull's stern end, forms a wide, elevated surface (s) which comprises the stern half of the hull, and which thus permits utilization of a propulsion system characteristic for this hull configuration consisting of a support hydroplane (p) extending transversely in the horizontal plane across the full breadth of the hull, having a streamlined shape, and being fixed or rotatable about a horizontal axis in connection with supports (q), optionally provided with one or more horizontal rudders (h) at the aft edge, and wherein a plurality of propulsion units (f) are mounted at the fore or aft edge of the support plane, above or beneath it.

[0012] According to the preferred embodiment of the invention, a transverse section through the hull configuration below the design waterline (dwl) at a distance of about 0.15 L from the stern, will have a ratio between the breadth (B_i) at the design waterline and the depth (t₁) of the hull measured from the same waterline which will be about 3 or greater than the corresponding ratio for a section at L/2 where the breadth (Bv and depth (to are measured in the same way.

[0013] As a result of the invention, the hull parameter e = c_p/c_dwl will preferably be about 1 or greater than 1, where cp is defined as the hull's longitudinal prismatic coefficient expressed as the ratio between the displacement volume V to the design waterline and the volume of a body equal to the area of a transverse section up to the design waterline at L/2, designated A_L/2, multiplied by the design waterline L, which may be expressed by the equation cp = V/A_L/2 · L, and where c_dwl is the waterline coefficient for the design waterline, defined as the ratio between the waterline area A_dw, and the product L · B where B is the maximum breadth at the waterline, which may be expressed by the equation c_dwl = A_dwl/LB.

[0014] As a result of the invention, the design waterline's areal center of gravity (LCF) will be located around 0.2 L aft of L/2 and the improved hull's volumetric center of gravity (buoyancy) (LCB) at the depth of the design waterline (dwl) around 0.075 L forward of the areal center of gravity, which may be expressed as LCF - LCB = 0.075 L.

[0015] The hull configuration according to the inven- _ tion can in the region from the stern post and forward to about 0.3 L be provided with turbulence-controlling appendages which may consist of fixed or flexible fin-like means (v) in the streamline direction mounted approximately perpendicular relative to the hull and located approximately at the transition between the bottom and sides of the hull, or as longitudinal grooves in the form of pointed, rectangular or wave-like grooves (x) which decrease in depth in the direction of forward propulsion and which at about 0.3 L terminate in and coincide with the even portion of the oblique surface (s) and whose depth (d) will usually be about 0.02 B.

[0016] The improved hull configuration of an exemplary embodiment of the invention is shown in the accompanying figures 1, 2, 3, 4, 5, 6 and 7.

Figure 1 shows the improved hull configuration's squarely cut off, approximately harmonic sinusoidal waterlines around the design waterline (dwl) with extremity points around the hull's bow and stern ends, with the areal center of . gravity (LCF) about 0.2 L astern of L/2 and where the length/breadth ratio L/B of the design waterline is shown as being about 2.

Figure 2 shows the improved hull below the design waterline (dwl) in vertical section, where it may be seen that the base lines of the squarely cut off, approximately harmonic sinusoidal waterlines (0_dwl, 0₁, 0₂, 0₃) along an oblique plane surface (s), which are displaced in the direction of forward propulsion of the vessel, coincide with the base plane (g) at about L/2, and the distance between the areal center of gravity (LCF) and the buoyancy center of gravity (LCB) of the hull at the depth of the design waterline (dwl) is about 0,075 L.

Figure 3 shows the improved hull configuration of Figure 2 in horizontal projection with the waterlines dwl, 1, 2,3 and g, in the example with a U-frame at the bow end of the hull, but other known frame forms can also be utilized, as required.

Figure 3 also shows the characteristic ratio between breadth and depth for a section around 0.1 L from the stern and at L/2, where the respective breadths and depths are designated B₁ and B₂ and t₁ and t₂.

Figure 4 shows a vertical section near the center plane in the hull's aft-section with the base plane (g), oblique plane (s), support (q), support hydro-plane (p), horizontal rudder (h), propulsion units (f) and vertical rudder (r), in this case shown with the propulsion unit (f) positioned in front of and underneath the support plane (p), but the thrusters can also be mounted at the aft end or above the support plane.

Figure 5 shows a section parallel to and below the oblique plane (s), support plane (p), supports (q), horizontal rudders (h), the overlying contour of the design waterline (dwl) and the propulsion units (f), in this example four in number and mounted at the forward edge of the support plane.

figure 6 shows the improved hull configuration's design waterline (dwl). On the upper half of the figure, an example of placement of the fin-like appendages (v) mounted in connection with the oblique plane (s) may be seen. On the lower half of the figure, an example may be seen of the groove-patterned portion (x) of the oblique plane (s). Both of these are indicated by broken lines in the drawing. The line A-A in Figure 6 is a transverse section through the stern portion of the oblique plane (s), shown again in Figure 7 with turbulence-controlling, fixed or flexible appendages (v) on the left-hand side of the figure and an example of longitudinally oriented grooves or ridges (x) on the right-hand side, showing the approximate depth (d) of the grooves in relation to the oblique plane (s).

Claims

1. A hull of the displacement type, having squarely cut off, longitudinally approximately sinusoidal waterlines defining a half wavelength at each side of the hull with stationary points of the curves at or adjacent the hull's fore and aft end points, and wherein the waterlines' base lines (0_dwl, 0₁, O2, 0₃) gradually, with increasing depth from the design waterline (dwl), are displaced in the direction of forward propulsion until they become tangential with the base plane (g) at about L/2, whereby an approximately oblique surface (s) through the base lines (0_dwl, 0₁, 0₂, 0₃) forms a broad termination at the stern half of the hull, under which there is mounted in the horizontal plane, transversely positioned, and fixed or rotatable about a transverse axis, a support hydro-plane (p) provided with propulsion units (f) distributed across the width of the support plane, mounted above or below said plane at the forward or aft edge thereof.

2. A hull according to claim 1, wherein the displacement in the longitudinal direction is distributed approximately.on a Rayleigh curve.

3. A hull according to claims 1 and 2, wherein the hull parameter e = c_p/c_dwl is about 1 or greater than 1, where cp is defined as the longitudinal prismatic coefficient expressed as the ratio between displacement volume V to the design waterline (dwl) and the volume of a body constituted by a cross-sectional area corresponding to that of a transverse section up to the design waterline (dwl) and passing through its half- length L, designated A_L/2, multiplied by the length L of the design waterline, and where c_dwl is defined as the waterline coefficient expressed by the ratio between the area enclosed by the design waterline and the maximum length L of the design waterline multiplied by its maximum breadth B.

4. A hull according to claim 1, wherein the number representing leanness of line L/V^1/3 is about 3 or greater than 3, wherein L is the length of the design waterline and V is the displacement volume of the hull configuration below the design waterline (dwl) to the maximum depth (T) for which the hull is designed.

5. A hull according to claim 1, wherein the ratio between the hull's maximum length and the breadth measured at the waterline at the maximum depth (T) for which the hull is designed is about 2 or greater than 2..

6. A hull according to claim 1, wherein the ratio between a transverse breadth (B_i, B₂) and depth (t₁, t₂) is at least three times larger at a section measured at about 0.15 L from the stern than at U2, where L is the length of the waterline at the depth for which the hull is designed.

7. A hull according to claim 1, wherein the oblique surface (s) in longitudinal section is formed approximately as a sine wave with stationary points at L/2 and the hull's stern end.

8. A hull according to claim 1, having one or _ more, fixed or flexible, plateshaped appendages (v) mounted approximately perpendicular relative to the surface of the hull on both sides thereof at the transition between the bottom and sides of the hull, mounted in the streamline direction within about 0.3 L from the stern end of the hull.

9. A hull according to claim 1, wherein the aft portion of the oblique surface (s) is made with longitudinally oriented, pointed, rectangular or wave-like grooves (x) which at about 0.3 L terminate in and become coincident with the oblique surface (s).

Ansprüche

1. Schiffsrumpf des Verdrängertyps, gekennzeichnet durch rechtwinkelig abgerissene, in Längsrichtung annähernd sinusförmige Wasserlinien, die an jeder Seite des Rumpfes eine halbe Wellenlänge definieren, und stationäre Kurvenabschnitte bei oder im Bereich der vorderen und hinteren Endpunkte des Rumpfes, wobei die Basislinien (0_dwl, 0₁, 0₂, 0₃) der Wasserlinien mit zunehmender Tiefe allmählich von der Designwasserlinie (dwl) in Richtung des Vorwärtstriebes verschoben sind, bis sie bei L/2 tangential zur Grundebene (g) verlaufen, wodurch eine im wesentlichen schräge, durch die Basislinien (0_dwl, 0₁, O₂, 0₃) verlaufende Fläche (s) ein breites Auslaufende an der Heckhälfte des Rumpfes bildet, unter welcher in einer Horizontalebene eine quer verlaufende fixe oder um eine Querachse schwenkbare Hydrotragfläche (p) angeordnet ist, die mit über die Breite der Tragfläche verteilten Antriebseinheiten (f) versehen ist, welche über oder unter der Tragfläche an der vorderen oder hinteren Kante derselben angebracht sind.

2. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß die Verschiebung in Längsrichtung im wesentlichen nach einer Rayleigh-Kurve verteilt ist.

3. Rumpf nach Patentanspruch 1 und 2, dadurch gekennzeichnet, daß der Rumpfparameter e = c_p/c_dwl etwa 1 oder größer als 1 ist, wobei cp als der longitudinale prismatische Koeffizient definiert ist, der als Verhältnis zwischen dem Verdrängungsvolumen V bis zur Designwasserlinie (dwl) und dem Volumen eines Körpers ausgedrückt ist, der bestimmt ist durch eine Querschnittsfläche, die einem bis zur Designwasserlinie (dwl) reichenden und durch seine halbe Länge L mit der Bezeichnung A_u2 verlaufenden Querschnitt entspricht, multipliziert mit der Länge der Designwasserlinie, und wobei c_dwl als Wasserlinienkoeffizient definiert ist, der als Verhältnis zwischen der von der Designwasserlinie umschlossenen Fläche und der maximalen Länge L der Designwasserlinie multipliziert mit ihrer maximalen Breite B ausgedrückt ist.

4. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß die Neigung der Linie L/V^1/3 definierende Zahl etwa 3 oder größer als 3 ist, wobei L die Länge der Designwasserlinie und V das Verdrängungsvolumen des Schiffsrumpfes unterhalb der Designwasserlinie (dwl) bis zur maximalen Tiefe (T) bedeutet, für die der Rumpf ausgelegt ist.

5. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß das Verhältnis zwischen der maximalen Länge und der Breite des Rumpfes an der Wasserlinie bei der maximalen Tiefe (T), für die der Rumpf ausgelegt ist, etwa 2 oder größer als 2 ist.

6. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß das Verhältnis zwischen einer Querbreite (B₁, B₂) und Tiefe (t₁, t₂) bei einem etwa 0,15 L vom Heck gemessenen Querschnitt mindestens dreimal größer ist als bei L/2, wobei L die Länge der Wasserlinie bei jener Tiefe bedeutet, für die der Rumpf ausgelegt ist.

7. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß die schräge Fläche (s) im Längsschnitt im wesentlichen als Sinuswelle mit stationären Kurvenabschnitten bei L/2 und beim Heck des Rumpfes geformt ist.

8. Rumpf nach Patentanspruch 1, gekennzeichnet durch einen oder mehrere, fixe oder flexible plattenförmige Vorsprünge (v), die im wesentlichen senkrecht zur Oberfläche des Rumpfes zu beiden Seiten desselben am Übergang zwischen dem Boden und den Seiten des Rumpfes angeordnet sind und die in Richtung der Strömungslinie innerhalb von etwa 0,3 L vom Heck des Rumpfes verlaufen.

9. Rumpf nach Patentanspruch 1, dadurch gekennzeichnet, daß der Heckabschnitt der schrägen Fläche (s) mit längsverlaufenden, spitzen, rechteckigen oder wellenartigen Nuten (x) versehen ist, die bei etwa 0,3 L in der schrägen Fläche (s) enden und in dieser verlaufen.

Revendications

1. Carène du type à déplacement, possédant des lignes d'eau coupées à angle droit, sensiblement sinusoïdales dans la direction longitudinale et définissant une demi-longueur d'onde de chaque côté de la carène, les sommets des courbes étant situés sur les points extrêmes avant et arrière de la carène ou au voisinage de ces points, et dans laquelle les lignes de base (0_dwl, 0₁, O2, 0₃) sont, pour une profondeur croissante à partir de la ligne de flottaison idéale (dwl), décalées progressivement dans la direction de la propulsion vers l'avant jusqu'à devenir tangentielles avec le plan de base (g) à une distance d'environ L/2, une surface (s) approximativement oblique qui passe par les lignes de base (0_dwl, 0₁, 0₂, 0₃) formant dans la moitié arrière de la carène une extrémité large au-dessous de laquelle est monté dans un plan horizontal, en position transversale et fixe ou tournant autour d'un axe transversal, un plan de sustentation hydraulique (p) pourvu d'unités de propulsion (f) réparties sur la largeur de ce plan de sustentation, et montées au-dessus ou au-dessous de ce plan vers le bord avant ou le bord arrière de celui-ci.

2. Carène selon la revendication 1, dans laquelle le déplacement en direction longitudinale est distribué approximativement selon une courbe de Rayleigh.

3. Carène selon les revendications 1 et 2, dans laquelle le paramètre de carène e = c_p/c_dwl est voisin de 1 ou supérieur à 1, cp étant défini comme le coefficient prismatique longitudinal exprimant le rapport entre le volume de déplacement V à la ligne de flottaison idéale (dwl) et le volume d'un corps réalisé avec une section dont l'aire correspond à celle de la section transversale jusqu'à la ligne de flottaison idéale (dwl) et passant à la moitié de la longueur L de celle-ci, cette aire désignée par A_U2 étant multipliée par la longueur L de la ligne de flottaison idéale, tandis que c_dwl est défini comme le coefficient de flottaison exprimant le rapport entre l'aire délimitée par la ligne de flottaison idéale et le produit de la longueur maximum L de la ligne de flottaison idéale par sa largeur maximum.

4. Carène selon la revendication 1, dans laquelle le nombre représentant la finesse de ligne L/V^1/3 est voisin de 3 ou supérieur à 3, L étant la longueur de la ligne de flottaison idéale et V étant le volume de déplacement de la forme de carène situé au-dessous de la ligne de flottaison idéale (dwl) et s'étendant jusqu'à la profondeur maximum (T) de la carène.

5. Carène selon la revendication 1, dans laquelle le rapport entre la longueur maximum et la largeur maximum de la carène, mesurées sur la ligne d'eau située à la profondeur maximum (T) de la carène, est voisin de 2 ou supérieur à 2.

6. Carène selon la revendication 1, dans laquelle le rapport entre la largeur transversale (B_i, B₂) et la profondeur (t_l, t₂) est au moins trois fois plus grand dans une section située à une distance d'environ 0,15 L de l'arrière qu'à une distance de L/2, L étant la longueur de la ligne d'eau correspondant au tirant d'eau pour lequel est prévue la carène.

7. Carène selon la revendication 1, dans laquelle la surface oblique (s) présente, en section longitudinale, sensiblement une forme d'onde sinusoïdale avec des sommets situés à L/2 et à l'extrémité arrière de la carène.

8. Carène selon la revendication 1, dans laquelle une ou plusieurs dérives (v) en forme de plaques, fixes ou flexibles, sont montées sensiblement perpendiculairement à la surface de la carène, sur les deux côtés de celle-ci, dans la zone de transition entre le fond et les parois latérales de la carène, ces dérives étant disposées suivant la direction longitudinale dans une partie s'étendant sur environ 0,3 L à partir de l'extrémité arrière de la carène.

9. Carène selon la revendication 1, dans laquelle la partie arrière de la surface oblique (s) comporte des gorges (x) orientées en direction longitudinale, de forme pointue, rectangulaire ou ondulée, qui se terminent à une distance d'environ 0,3 L en venant se confondre avec la surface oblique (s).

Drawing