Abstract
The invention relates to a hydrofoil system for a marine vessel comprising a hull (101), the hydrofoil system comprising at least one pair of foldable hydrofoils (109, 110) which are pivoted relative to the marine vessel, wherein each hydrofoil (109, 110) is controllable by at least one actuator (930) for displacement of the at least one pair of foldable hydrofoils in a lateral direction of the marine vessel between a stowed position and a deployed position. Each foldable hydrofoil (109, 110) is hinged relative to the hull above the water line on opposite sides of the marine vessel. A first portion (111) of each hydrofoil extends adjacent the hull (101) towards the water line of the marine vessel when the hydrofoil is in the stowed position and a second portion (112) comprises a free second end extending under the hull. The second portion (112) is submerged and arranged in a lateral recess (107) behind a stepped hull portion (106) of the marine vessel when the hydrofoil is in the stowed position.
Claims
1. A hydrofoil system for a marine vessel comprising a hull, the hydrofoil system comprising at least one pair of foldable hydrofoils which are pivoted relative to the marine vessel, wherein each hydrofoil is controllable by at least one actuator for displacement of the at least one pair of foldable hydrofoils in a lateral direction of the marine vessel between a stowed position and a deployed position, characterized in that each foldable hydrofoil comprises a first portion comprising an upper end mounted hinged relative to the hull above the water line on opposite sides of the marine vessel; wherein each first portion extends adjacent the hull between the upper end and the water line of the marine vessel when the hydrofoil is in the stowed position; and each foldable hydrofoil comprises a second portion comprising a free second end extending under the hull; wherein the second portion is submerged and arranged in a lateral recess behind a stepped hull portion of the marine vessel when the hydrofoil is in the stowed position.
2. A hydrofoil system according to claim 1, characterized in that at least the submerged portions of the hydrofoils are located in the lateral recess behind the stepped hull portion of the marine vessel when the hydrofoils are in the stowed position.
3. A hydrofoil system according to claim 1, characterized in that a lower outer surface of each hydrofoil is at least flush with the submerged outer surface of the hull in front of the stepped hull portion when the hydrofoils are in the stowed position.
4. A hydrofoil system according to claim 1, characterized in that an outer side surface of each hydrofoil is located in a recess in the side of the hull above the water line when the hydrofoil is in the stowed position.
5. A hydrofoil system according to claim 1, characterized in that each hydrofoil comprises a single structural component having a shape conforming with the outer surface of the hull above and below the water line.
6. A hydrofoil system according to claim 1, characterized in that the first end of each foldable hydrofoil comprises a hinge having parallel pivot axes extending in the longitudinal direction of the marine vessel.
7. A hydrofoil system according to claim 1, characterized in that the second end of each hydrofoil extends at least up to the central longitudinal axis of the marine vessel.
8. A hydrofoil system according to claim 7, characterized in that that the second ends of each pair of hydrofoils are arranged to extend a predetermined distance past the central longitudinal axis of the marine vessel.
9. A hydrofoil system according to claim 8, characterized in that the second ends of each pair of hydrofoils are arranged to overlap when the hydrofoils are in the stowed position.
10. A hydrofoil system according to claim 9, characterized in that the overlapping hydrofoils are arranged to be displaced sequentially when moved towards the deployed position.
11. A hydrofoil system according to claim 8, characterized in that the second ends of each pair of hydrofoils are arranged to extend side-by-side adjacent the hull when the hydrofoils are in the stowed position.
12. A hydrofoil system according to claim 11, characterized in that the first end of one of the foldable hydrofoils comprises a hinge having a pivot axis extending at an angle to the horizontal plane in the longitudinal direction of the marine vessel.
13. A hydrofoil system according to claim 1, characterized in that each first portion extends downwards at right angles to the water line when the hydrofoil is in the stowed position.
14. A hydrofoil system according to claim 1, characterized in that each first portion extends downwards and rearwards at a predetermined angle to the water line when the hydrofoil is in the stowed position.
15. A hydrofoil system according to claim 1, characterized in that each hydrofoil is connected to at least one actuator arranged within the hull of the marine vessel, wherein the at least one actuator is arranged to displace the hydrofoils between their stowed and deployed positions.
16. A hydrofoil system according to claim 15, characterized in that the at least one actuator are arranged below the water line within the hull of the marine vessel.
17. Marine vessel characterized in that the marine vessel is provided with a hydrofoil system according to claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. In the drawings:
(2) FIG. 1 shows a side view of a schematically illustrated vessel comprising a hydrofoil system according to the invention;
(3) FIG. 2 shows a schematically illustrated vessel with a stepped hull;
(4) FIG. 3A-C show a schematic illustration of a hydrofoil system according to the invention and how it is deployed;
(5) FIG. 4 shows a schematic side view of a first example of the hydrofoil system;
(6) FIG. 5 shows a schematic side view of a second example of the hydrofoil system;
(7) FIG. 6 shows a schematic side view of a third example of the hydrofoil system;
(8) FIG. 7 shows a schematic lower view of the hydrofoil system in FIGS. 4 and 5;
(9) FIG. 8 shows a schematic lower view of the hydrofoil system in FIG. 6; and
(10) FIG. 9 shows a schematic illustration of an actuator for controlling a hydrofoil system according to the invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
(11) FIG. 1 shows a side view of a schematically illustrated marine vessel 100 comprising a hull 101 provided with a hydrofoil system according to the invention. The hydrofoil system in this example comprises a pair of foldable hydrofoils 109, 110 which are pivoted relative to the marine vessel. In this figure only a first hydrofoil 110 is visible, while a second hydrofoil 109 (arrow in dashed lines) is located on the opposite side of the hull 101. Each hydrofoil 109, 110 is controllable by at least one actuator (see FIG. 9, “930”) for displacement of the foldable hydrofoils 109, 110 in a lateral direction of the marine vessel between a stowed position and a deployed position, as indicated by the arrow A1. FIG. 1 shows the hydrofoils 109, 110 in the deployed position, with the hull lifted out of the water 120. Each foldable hydrofoil comprises a first portion 111 comprising an upper end mounted by a hinge 113 relative to the hull above the water line on opposite sides of the marine vessel. In this example, the hinge 113 is pivoted about an axis parallel to the longitudinal axis of the vessel. Each first portion 111 extends adjacent the hull between the upper end and the water line of the marine vessel when the hydrofoil is in the stowed position (see FIG. 3A). Each foldable hydrofoil 109, 110 further comprise a second portion 112 comprising a free second end extending under the hull. The second portion 112 is submerged and arranged in a lateral recess 107 behind a stepped hull portion 106 of the marine vessel when the hydrofoil is in the stowed position. As shown in FIG. 1, the hull 101 comprises a bow section 104 extending rearwards from the bow 102 to the stepped hull portion 106 and a stern section 105 extending rearwards from the stepped hull portion 106 to the stern 103. FIG. 1 further shows a schematically indicated drive unit 121 connected to the stern 103 by an actuating means 122 that can adjust the position of the drive unit 121 in the vertical direction, as shown by arrow A2. The drive unit 121 is adjusted vertically together with the hydrofoils 109, 110 in order to maintain it submerged.
(12) FIG. 2 shows a schematically illustrated vessel with a stepped hull. FIG. 2 shows a hull 201 comprising a bow section 204 extending rearwards from the bow 202 to a stepped hull portion 206 and a stern section 205 extending rearwards from the stepped hull portion 206 to the stern 203. The stepped hull portion 206 is a break or lateral recess 207 in the hull 204 intended to reduce the wetted surface of the hull. Such steps can run straight across the hull (as shown in FIG. 2) or can be V-shaped, with the vertex facing forward or rearward. FIG. 2 further shows an optional recess 208 in the side of the hull 104. This recess 208 extending above the water line and can be provided to accommodate the first portion of a hydrofoil (not shown) in order to further reduce drag.
(13) FIG. 3A-C show a schematic illustration of a hydrofoil system according to the invention and how it is deployed. FIG. 3A shows a cross-sectional rear view through the hull 301 and a pair of hydrofoils 309, 310 located in their stowed positions. Each foldable hydrofoil comprises a first portion 311, 315 comprising an upper end mounted by a hinge 313, 317 relative to the hull 301 above the water line on opposite sides of the marine vessel. Each first portion 311, 315 extends adjacent the hull between the upper end and the water line of the marine vessel. Each foldable hydrofoil 309, 310 further comprise a second portion 312, 316 comprising a free second end 318, 319 extending under the hull past the central longitudinal axis P. The second portions 312, 316 are submerged and arranged in a lateral recess behind a stepped hull portion 306 separating a bow section 304 and a stern section 305 of the hull 301 of the marine vessel. As indicated in FIG. 3A, both hydrofoils 309, 310 are located inside the outer envelope, or rearward extension, of the bow section 304 of the hull. In this way, the hydrofoils avoids causing an increased drag in the water flowing past the bow section 304 and the stepped hull portion 306 when travelling at relatively low speeds.
(14) FIG. 3B shows an initial stage of the deployment of the foldable hydrofoils 309, 310. During deployment, an actuator (not shown) causes the hydrofoils to be rotated about their respective hinges 313, 317, as indicated by arrows in FIG. 3B. As shown in this example, the outermost hydrofoil 310 is deployed first, followed by the innermost hydrofoil 309.
(15) FIG. 3C shows the foldable hydrofoils 309, 310 in their fully deployed, operational positions, when the vessel is travelling a speed sufficient for creating a lifting force that lifts the entire hull 301 above the surface of the water S. In the deployed position, the vessel is mainly supported by the submerged parts of the second portions 318, 319 of the hydrofoils 309, 310. The stern of the vessel will be supported by an additional lifting force provided by the drive unit (not shown), which can comprise separate hydrofoil surfaces.
(16) FIG. 4 shows a schematic side view of a first example of the hydrofoil system. FIG. 4 shows a hull 401 comprising a stepped hull portion 406 separating a bow section 404 and a stern section 405 of the hull 401 of the marine vessel. The figure shows one hydrofoil 410 comprising an upper, first portion 411 and a lower, second portion 412. An identical hydrofoil is mounted on the opposite side of the hull 401. In this example, the hydrofoil 410 is in its stowed position and is mounted by a hinge 413 placed at an angle β relative to the horizontal plane. The angle of at least the first portion 411 of the hydrofoil 410 can be selected independently of the angle of the hinge 413. However, in FIG. 4 the first portion 411 extends at right angles to the axis of the angled hinge 413, corresponding to an angle α relative to the water line, where α=90°−β. Within the scope of the invention, the angle of the first portion of the hydrofoil can be selected to conform to the cross-sectional shape of stepped hull portion, above and/or below the water line. Hence, the angle of the first portion of the hydrofoil can be selected independently of the angle of the hinge supporting each hydrofoil. This arrangement will require a corresponding angle β between the first and second portions 411, 412 of the hydrofoil with the angled hinge, in order to place its submerged second portion in a substantially horizontal position for generating a sufficient lifting force.
(17) FIG. 5 shows a schematic side view of a second example of the hydrofoil system. FIG. 5 shows a hull 501 comprising a stepped hull portion 506 separating a bow section 504 and a stern section 505 of the hull 501 of the marine vessel. The figure shows one hydrofoil 510 comprising an upper, first portion 511 and a lower, second portion 512. An identical hydrofoil is mounted on the opposite side of the hull 501. In this example, the hydrofoil 510 is in its stowed position and is mounted by a hinge 513 placed in the horizontal plane, corresponding to an angle β of 0° compared to FIG. 4. Further, the first portion 511 extends at right angles to the axis of the horizontal hinge 513, corresponding to an angle α at right angles to the water line.
(18) FIG. 7 shows a schematic lower view of the hydrofoil system in FIG. 5. FIG. 7 shows a hull comprising a stepped hull portion 706 separating a bow section 704 and a stern section 705 of the hull of the marine vessel. The hydrofoil system comprises a first hydrofoil 710 having a first portion 711 and a second portion 712 and a second hydrofoil 709 having a first portion 715 and a second portion 716. The second portions 712, 716 have free end portions 718, 719 extending past the longitudinal axis L of the vessel in an overlapping relationship. According to this example, the first portions 711, 715 of the overlapping first and second hydrofoils 710, 709 comprise a hinges (FIG. 5; “513”) having pivot axes extending in the horizontal plane in the longitudinal direction of the marine vessel.
(19) During deployment, the overlapping hydrofoils 710, 709 are arranged to be displaced sequentially when moved towards their operative positions, wherein the outermost, first hydrofoil 710 is actuated first (see FIG. 3B) followed by the innermost hydrofoil 709. During retraction of the hydrofoils towards the stowed position the hydrofoils are actuated in reverse, wherein the innermost hydrofoil 709 is actuated first.
(20) FIG. 6 shows a schematic side view of a third example of the hydrofoil system. FIG. 6 shows a hull 601 comprising a stepped hull portion 606 separating a bow section 604 and a stern section 605 of the hull 601 of the marine vessel. The figure shows a first hydrofoil 610 comprising an upper, first portion 611 and a lower, second portion 612. In this example, the first hydrofoil 610 is in its stowed position and is mounted by a hinge 613 placed at an angle β relative to the horizontal plane. The figure further shows second hydrofoil 609 comprising an upper, first portion 615 and a lower, second portion 616. In this example, the hydrofoil 610 is in its stowed position and is mounted by a hinge 613 placed in the horizontal plane.
(21) The arrangement shown in FIG. 6 can be used for the example in FIG. 8, which shows a schematic lower view of the underside of the hydrofoil system in FIG. 6. FIG. 8 shows a hull comprising a stepped hull portion 806 separating a bow section 804 and a stern section 805 of the hull of the marine vessel. The hydrofoil system comprises a first hydrofoil 810 having a first portion 811 and a second portion 812 and a second hydrofoil 809 having a first portion 815 and a second portion 816. The second portions 812, 816 have free end portions 818, 819 extending past the longitudinal axis L of the vessel in a side-by-side relationship. According to this example, the first portion 811 of the first hydrofoil 810 in the side-by-side arrangement comprises a hinge (FIG. 6; “613”) having a pivot axis extending at an angle to the horizontal plane in the longitudinal direction of the marine vessel. However, the first portion 815 of the second hydrofoil 809 comprises a hinge (see FIG. 5) having a pivot axis extending in the horizontal plane in the longitudinal direction of the marine vessel.
(22) When the hydrofoils are deployed, the side-by-side offset between the submerged second ends 818, 819 of each hydrofoil 810, 809 in the longitudinal direction of the vessel can be reduced or eliminated when each hydrofoil reaches its operative position. This effect is achieved by the angled hinge, which causes the second portion 812 of the first hydrofoil 810 to be displaced rearwards relative its stowed longitudinal position. Consequently, the generated moment requiring a steering correction in order to maintain the vessel on a straight heading can be reduced or eliminated. This arrangement will require a corresponding angle between the first and second portions of the hydrofoil with the angled hinge, in order to place its submerged second portion in a substantially horizontal position for generating a sufficient lifting force.
(23) Alternative solutions can include angling the hinge of the second hydrofoil in the opposite direction, or to provide means for longitudinal displacement for one or both hydrofoils.
(24) FIG. 9 shows a schematic illustration of an actuator for controlling a hydrofoil system according to the invention. FIG. 9 shows a cross-sectional rear view through the hull 901 and a pair of hydrofoils 909, 910 located in their stowed positions. Each foldable hydrofoil comprises a first portion 911, 915 comprising an upper end mounted by a hinge (see FIG. 3A) relative to the hull 901 above the water line on opposite sides of the marine vessel. Each first portion 911, 915 extends adjacent the hull between the upper end and the water line of the marine vessel. Each foldable hydrofoil 909, 910 further comprises a second portion 912, 916 comprising a free second end 918, 919 extending under the hull past its central longitudinal axis. The second portions 912, 916 are submerged and arranged in a lateral recess behind a stepped hull portion in the hull 301 of the marine vessel. The hydrofoils 909, 910 are connected to an actuator 930 arranged within the hull 901 of the marine vessel, which actuator are arranged to displace the hydrofoils between their stowed and deployed positions (see FIG. 3C).
(25) FIG. 9 shows a single, common actuator for displacement of the hydrofoils. However, each hydrofoil can be connected to at least one actuator arranged within the hull of the marine vessel, which actuator is arranged to displace the hydrofoils between their stowed and fully deployed positions. The size and number of actuators is dependent on the force required to deploy and maintain the hydrofoils in their operative positions. Consequently, the hydrofoils can be operated by a single, common actuator, or by one or more actuators for each hydrofoil. According to one example, the at least one actuator is arranged below the water line within the hull of the marine vessel. The at least one actuator is preferably arranged below the water line within the hull of the marine vessel.
(26) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. For instance, vessels may comprise fixed hydrofoils or hydrofoils with control surfaces as indicated in the background. Although no such features are described in the above examples, the invention is applicable to both types of hydrofoils.
