초록 ▼

The invention relates to a vessel for operating on a body of water comprising: a non-planing hull having a waterline and a longitudinal direction with a forward portion, an aft portion, and a central portion, the hull being configured to have the aft portion with a smaller water displacement relativ

The invention relates to a vessel for operating on a body of water comprising: a non-planing hull having a waterline and a longitudinal direction with a forward portion, an aft portion, and a central portion, the hull being configured to have the aft portion with a smaller water displacement relative to a water displacement at the central portion; and an aft foil affixed to the aft hull portion with one or more connecting members, and below the surface of the water, and spaced from the hull, the aft foil having a span, a chord, and a leading edge and a trailing edge relative to a forward direction, wherein the leading edge of the aft foil is tilted at a downward angle relative to the horizontal, wherein the aft foil has a chord and profile in longitudinal cross section, with a configuration to provide a lifting force, the tilt angle of the chord of the aft foil being measured with respect to the horizontal, and wherein the aft foil is oriented to provide a continuous, upward, forwardly directed component of the lifting force.

대표청구항 ▼

1. Vessel (1) for operating on a body of water (2) comprising: a non-planing hull (3) having a waterline (4) and a longitudinal direction (5) with a forward portion (6), an aft portion (8), and a central portion (7), the hull being configured to have the aft portion with a smaller water displacement

1. Vessel (1) for operating on a body of water (2) comprising: a non-planing hull (3) having a waterline (4) and a longitudinal direction (5) with a forward portion (6), an aft portion (8), and a central portion (7), the hull being configured to have the aft portion with a smaller water displacement relative to a water displacement at the central portion; andan aft foil (9) affixed to the aft hull portion with one or more connecting members (13), and below the surface of the water, and spaced from the hull, the aft foil having a span (ba), a chord (ca), and a leading edge (10) and a trailing edge (11) relative to a forward direction (12),wherein the leading edge of the aft foil is aligned with the horizontal or tilted at an upward or downward angle (α) relative to the horizontal,wherein the aft foil has a chord and profile in longitudinal cross section, with a configuration to provide a lifting force (La), the tilt angle of the chord of the aft foil being measured with respect to the horizontal,and wherein the aft foil is oriented to provide a continuous, upward, forwardly directed component (La12) of the lifting force (La),wherein, during use, in the longitudinal direction the central portion of the hull displays a pressure transition region (18), wherein the pressure force on the hull changes from increasing drag forward of this region, to reducing drag aft of this region, characterized in thata forward foil (19) is positioned in front of the pressure transition region and the aft foil is positioned aft of the pressure transition region, the forward foil being arranged at a distance not greater than one chord length from the hull, whereby the low pressure on the upper side of the forward foil is continued on the hull above,wherein the aft and forward foils are configured to keep at least 50% to 70% of the submerged volume of the vessel, when stationary, below the waterline, the forward foil preventing the vessel to adopt a bow-down trim condition. 2. The vessel (1) according to claim 1, wherein the aft foil is connected to the aft hull portion by means of a pair of connecting members (13), the aft foil in spanwise direction being symmetrical with respect to a vertical mirror plane (14), wherein each of the connecting members connect to the aft foil in a junction region (16) at a spanwise distance (D1) from the mirror plane being 25 to 50%, of the span of the aft foil. 3. The vessel (1) according to claim 2, wherein the aft foil has foil tips (15) and each of the connecting members is located at a respective foil tip. 4. The vessel (1) according to claim 3, wherein the connecting members have a leading edge sweep angle (β) of 0 to 40° with respect to the vertical. 5. The vessel (1) according to claim 3, wherein the connecting members each comprise a rounded shape in a transverse vertical plane such as to afford a gradual transition from the aft foil to the vertical in the junction region (16). 6. The vessel (1) according to claim 5, wherein the rounded shape in the junction region has a maximum inner bend radius (Ri) of 1 times the chord length of the aft foil, and a minimum inner bend radius of 0.5 times the chord length of the aft foil. 7. The vessel (1) according to claim 2, wherein a sweep angle, in plan view, of the leading edge of the aft foil is 15 to 25°. 8. The vessel (1) according to claim 1, wherein at least half the chord of the aft foil is behind a vertical line through the location where the aft portion of the hull leaves the water. 9. The vessel (1) according to claim 2, wherein the connecting members possess a streamlined section shape (17) with respect to the forward direction with a chord length of 0.8 to 1.2 times the chord length of the aft foil. 10. The vessel (1) according to claim 9, wherein the chord length of the connecting members taper from a first chord length at a junction with the hull to a relatively smaller second chord length at the junction with the aft foil, the taper ratio being 0.5 to 0.9. 11. The vessel (1) according to claim 2, wherein the chord length of the aft foil tapers from a first chord length at the mirror plane to a relatively smaller second chord length at a foil tip, the taper ratio being 0.5 to 1.0. 12. The vessel (1) according to claim 1, wherein the forward foil in spanwise direction is symmetrical with respect to the vertical mirror plane, wherein the forward foil has a dihedral angle (∂), such that the distance (D3) of the foil from the hull remains substantially the same along the span of the foil. 13. The vessel (1) according to claim 1, wherein the dihedral angle is 5 to 50°. 14. The vessel (1) according to claim 1, wherein an aspect ratio of the forward foil is at least 4.0. 15. The vessel (1) according to claim 1, wherein an aspect ratio of the aft foil is approximately 4.0 to 7.0. 16. The vessel (1) according to claim 1, wherein the span of both the forward and aft foil is at most 90% of a vessel's hull width at the longitudinal position of the respective foil. 17. The vessel (1) according to claim 1, wherein the forward foil is tilted at a tilting angle (φ) with the leading edge upwards 0 to 10° with respect to the horizontal. 18. The vessel (1) according to claim 2, wherein the connecting members comprise a connecting member foil (17) with a chord (cc), and a leading edge (20) and a trailing edge (21) relative to a forward direction, wherein the connecting member foil has a chord and profile in longitudinal cross section, with a configuration to provide a lifting force (Lc),and wherein the connecting member foil is oriented to provide a continuous, sideways and forward-directed component of the lifting force (Lc12) to amplify the forward-directed component (La12) generated by the aft foil. 19. The vessel (1) according to claim 15, wherein an angle (ψ) between the chord of the connecting member foil, and the vertical mirror plane is between 0 to 10° in the case of the aft foil, and between 0 to −10° in the case of the forward foil. 20. The vessel (1) according to claim 1, wherein the connecting members (13) are each connected to the aft foil by means of a nacelle (25) at a connection point at a spanwise distance from the mirror plane of 30 to 40% of the span of the aft foil.