WO2014025257A1

WO2014025257A1 - Vessel with three hulls having forward hydrofoils

Info

Publication number: WO2014025257A1
Application number: PCT/NL2013/050586
Authority: WO
Inventors: Pieter Van Oossanen; Gerard Jelle Bilkert
Original assignee: Anwigema B.V.
Priority date: 2012-08-09
Filing date: 2013-08-08
Publication date: 2014-02-13
Also published as: NL2009307C2

Abstract

The invention relates to a vessel having a main hull structure extending in a length direction, comprising a deck and a bottom, a central hull having a bow and two side hulls projecting from the bottom of the main hull structure, wherein the planes of symmetry of the side hulls intersects each other in a plane of symmetry of the main hull structure above the deck, characterised in that the vessel comprises a pair of forward deflectors extending transversely to the length direction at a distance (H1) from the bottom, from a side hull connection region near a lower end of the side hulls to a central hull connection region near a mid section of the central hull.

Description

VESSEL WITH THREE HULLS HAVING FORWARD HYDROFOILS

Field of the invention [0001] The invention relates to a vessel having a main hull structure extending in a length direction, comprising a deck and a bottom, a central hull having a bow and two side hulls projecting from the bottom of the main hull structure, wherein the planes of symmetry of the side hulls intersects each other in a plane of symmetry of the main hull structure above the deck.

Background of the invention

[0002] Such a vessel having three hulls is known from EP0271939. This patent publication describes a sailing yacht having a cockpit and three essentially identical hulls, a central hull and two side hulls, going out from the bottom of the cockpit, the planes of symmetry of the two side hulls intersecting each other in a plane of symmetry of the cockpit above the deck of the sailing yacht.

[0003] A disadvantage of the known vessel with three hulls, however, is that hydrodynamic drag is relatively high. Furthermore, the stability of the known vessel could be improved. Improvements in stability and drag reduction are especially important when the vessel is a sailing yacht, as a sailing yacht's performance is more sensitive to drag and stability issues than a motor vessel's. [0004] It is an object of the present invention to provide a vessel with three hulls wherein hydrodynamic drag is reduced. A further object of the invention is to provide a vessel having three hulls wherein stability is improved.

Summary of the invention

[0005] Hereto the known vessel is characterized in that the vessel comprises a pair of forward deflectors extending transversely to the length direction at a distance from the bottom, from a side hull connection region near a lower end of the side hulls to a central hull connection region near a mid section of the central hull.

[0006] The fore mentioned deflectors bring about a reduction in hydrodynamic drag due to the fact that the wetted area of the central hull and the side hulls is significantly reduced due to the lift provided by the deflectors, e.g. hydrofoils, significantly decreasing drag. In addition, the formation of bow waves is reduced, providing for a further reduction in drag. Furthermore, stability of the vessel is improved, especially longitudinal pitch stability, due to the presence of the deflectors.

[0007] In a preferred embodiment, the forward deflectors are of substantially planar shape and extend in a transverse direction at an angle of between 0 and 45°, preferably between 0 and 25° to a horizontal plane. In this way an even smaller bow wave can be obtained, further reducing the drag of the vessel. Additionally, this deflector configuration reduces flow turbulence between the central hull and side hulls.

[0008] Another embodiment relates to a vessel wherein the side hull and central hull connection regions are situated at respective distances in the length direction LI, L2 from the bow, the distance LI being larger than the distance L2. Thus, a better vessel streamline is achieved.

[0009] A further embodiment concerns a vessel wherein the bottom of the side hulls extend in a forward region upwards towards deck level near the bow, a vertical distance H5 from the deck to the forward deflectors in the forward region being larger than a vertical distance H6 from the deck to the side hull bottoms.

[0010] A yet further embodiment relates to a vessel comprising a stern, and a pair of rearward deflectors near the stern extending transversely to the length direction at a distance from the bottom, from a side hull connection region near a lower end of the side hulls to a central hull connection region near a mid section of the central hull. These rearward deflectors improve pitch stability of the vessel and reduce the stern wake. [0011] Preferably, the rearward deflectors are of substantially planar shape and extend in a transverse direction at an angle of between 0 and 45, preferably between 0 and 25 degrees to a horizontal plane. Thus, the drag of the deflectors themselves is minimized. [0012] Furthermore, the rearward deflectors can extend transversely to the length direction to provide optimal pitch stability control.

[0013] The connection regions of the rearward deflectors can advantageously be situated near the bottom of the central hulls and of the side hulls to ensure optimal contact with the water.

[0014] The vessel can optionally be provided with means for changing the angle of incidence of the deflectors. Optimal drag reduction and stability control of the hydrofoils can thus be achieved, especially at different vessel speeds. Fore mentioned means can advantageously be used to set a trim angle at a certain vessel speed.

[0015] In an embodiment, the aspect ratio of the deflectors is high, i.e. yielding relatively slender hydrofoils in order to reduce the foils' friction drag. [0016] Furthermore, the side hulls can be provided with a pair of keels projecting from the keel portion of the side hulls in order to improve roll stability.

[0017] Each of these keels can be arranged at an angle of approximately 90° with respect to the forward and/or aft deflector at that respective side of the vessel, when viewed along the longitudinal axis thereof. Thus, the keels can be used to provide roll stability and the deflectors to improve pitch stability, while the two are substantially decoupled from each other due to the 90° angle.

[0018] To achieve a maximum effect on roll stability the keels can be arranged near the centre portion of the side hulls in longitudinal direction.

[0019] To further reduce drag, the central hull preferably has a substantially vertical bow portion extending downwards from the bow to a lower bow point, the bottom of the central hull extending from the lower bow point to a keel level of an angle d between 10 and 50°, preferably between 10 and 30°.

[0020] In practice, the above-mentioned invention is especially suitable for sailing yachts, where drag and stability issues are harder to deal with than with motor vessels, due to the lack of an engine and the use of a relatively high mast.

Brief description of the drawings [0021] An embodiment of a vessel according to the invention will by way of non- limiting example be described in detail with reference to the accompanying drawings. In the drawings:

[0022] Figure 1 shows a bottom view of an exemplary embodiment of the vessel,

[0023] Figure 2 shows a side view of the vessel, [0024] Figure 3 shows a front view of the vessel, [0025] Figure 4 shows a rear view of the vessel, and

[0026] Figure 5 shows a side view of another exemplary embodiment of the vessel. Detailed description of the invention

[0027] Figure 1 shows a bottom view of an exemplary embodiment of a vessel 1 according to the invention, having a main hull structure 10, comprising deck structures, such as a cockpit in the case of a sailing yacht, the main hull structure 10 extending in a length direction, comprising a deck 14 and a bottom 17, a central hull 2 having a bow 8 and two side hulls 3 projecting from the bottom of the main hull structure 10, wherein the planes of symmetry of the side hulls 3 intersects each other in a plane of symmetry of the main hull structure 10 above the deck 14 (not shown, to be discussed with reference to figure 3 that shows the same embodiment), the vessel 1 comprising a pair of forward deflectors 4 in the form of hydrofoils 5 extending transversely to the length direction at a distance HI (not shown, to be discussed with reference to figure 3) from the bottom 17, from a side hull 3 connection region CI, C2 near a lower end of the side hulls 3 to a central hull 2 connection region C3 near a mid section of the central hull 2. The length L of the vessel 1 (see figure 2) is approximately 15 m. Vessels having a length of approximately 7,5 m to 25 m are particularly suitable for use with the invention, although shorter or longer vessels can also be used therewith. The width B of the embodiment is close to 2/5 L, whereas the height H of the vessel (see figure 2) is approximately 1/4 - 1/5 L.

[0028] The right part of figure 1 shows the bow section of the vessel 1, whereas in the left part of figure 1 the stern is depicted. The bow portions of the central hull 2 and side hulls 3 are indicated by reference numerals 8a and 8b-8c, respectively, whereas the stern portions of the central hull 2 and side hulls 3 are indicated by 9a and 9b-9c, respectively. Forward deflectors 4 are shown in the form of a hydrofoil arrangement having a pair of hydrofoils 5 extending between the bow portion 8a of the central hull 2 and the side hulls 3. The hydrofoils 5 are swept back at an angle a with respect to the central hull 2. The angle a can be adapted to the angle of the bow wave that is to be expected, and can preferably be in the range of 0-45°, more preferably in the range of 0-25°, most preferably is around 45°. The side hulls 3 are provided with keels 7 to improve roll stability. The keels 7 also provide lateral force, required to reduce leeway when sailing upwind. These keels 7 are preferably positioned in the centre portion of the side hulls 3. Rudders 11 can be added to the side hulls 3 between the keels 7 and the stern portion of the vessel 1. When the vessel 1 uses an engine instead of a sail to achieve propulsion, the keels 7 and rudders 11 are preferably removed as they significantly increase drag.

[0029] Another pair of deflectors 16 in the form of a pair of rearward hydrofoils 6 is shown near the stern portions 9a, 9b, 9c of the vessel 1. The pair of rearward deflectors near the stern also extends transversely to the length direction at a distance H2 (not shown) from the bottom 17 and from a side hull connection region C4, C5 near a lower end of the side hulls 3 to a central hull connection region C6 near a mid section of the central hull 2. The projection of the wings 6 on the horizontal plane essentially yields two surfaces being aligned with each other, which, in practice, provides a significant reduction in the severity of the stern wake, thereby reducing water resistance. Preferably, the rearward hydrofoils 6 are positioned as far aft as possible for maximal effect. The rearward hydrofoils 6 can also be swept upwards or rearwards for further smoothening the transition of the flow under the vessel 1, i.e. the flow past the central hull 2 and side hulls 3, towards the flow in the stern wake.

[0030] Figure 2 shows a side view of the exemplary embodiment of the vessel 1 as shown in figure 1. A waterline is also shown, indicated by WL. It can now be more easily seen that the vessel 1 comprises a main hull structure 10 from which the central hull 2 and side hulls 3 project downwards. The side hull 3 and mid hull 2 connection regions CI, C2, C3 are situated at respective distances in the length direction LI, L2 from the most forward point on the bow portion 8a, the distance LI, for example being 1/4 L, being larger than the distance L2, for example 1/8 L. Additionally, the mid hull connection region C3 is positioned at a distance H4, for example 3/4 H, from the deck 14 of the vessel 1. The forward hydrofoils 5 are shown to be swept back in this respect under an angle a, as well as upwards under an angle βΐ with respect to a horizontal plane. This angle βΐ also depends on the geometry of the side hulls 3 and the central hull 2 relative to each other and lies preferably in the range of 0-45°, more preferably in the range of 0-25°, most preferably is around 20°.

[0031] Figure 3 shows a front view of the exemplary embodiment of the vessel 1 according to the invention. The planes of symmetry of the side hulls 3 can be seen to converge in the plane of symmetry of the main hull 10 above the deck 14, in the point S. The forward hydrofoils 5 are placed at a distance HI, for example being 1/4 H, from the bottom 17 of the vessel 1. Furthermore, they can be placed under a further angle β2 with respect to the horizontal plane. β2 preferably lies in the range of 0-45°, more preferably in the range of 0-25°, most preferably is around 20°. The connection regions CI, C2, C3 of the forward hydrofoils 5 can also be more easily discerned in figure 3. H3, for example having a height of 1/2 H, indicates the height of the central hull 2.

[0032] Furthermore, it can be seen that the keels 7 are placed under an angle γ of about 80-100°, more preferably 90° with respect to the hydrofoils 5, 6 when viewed in longitudinal direction. The centre lines of the central hull 2 and the side hulls 3 also converge at the most forward location on the deck 15 to provide for a more streamlined vessel 1. The hydrofoils 5 of the forward stabilizing arrangement 4 in this example connect in the bow section 8a of the central hull 2.

[0033] Figure 4 shows a rear view of the vessel 1. The rearward hydrofoils 6 connect in the stern portion 9a of the central hull 2. The connection regions C4, C5, C6 of the rearward hydrofoils 6 can also be more easily observed in figure 4. The rearward hydrofoils 6 are also placed under an angle β3 with respect to the horizontal plane. β3 preferably lies in the range of 0-45°, more preferably in the range of 0-25°, most preferably is around 15°. The rearward hydrofoils 6 are placed at a distance H2, for example being 1/4 H, from the bottom 17 of the vessel 1.

[0034] Figure 5 shows another exemplary embodiment of a vessel 1 wherein the vessel 1 has a central hull 2 with a straight, vertical stem 12 to further reduce water resistance. The side hull 3 and mid hull 2 connection regions C1-C3 can now more clearly be seen to be situated at respective distances in the length direction LI, L2 from the bow 8, the distance LI, for example being 1/3 L in this embodiment, being larger than the distance L2, for example being 1/9 L. Also, the forward hydrofoils 5 are shown in this variation to comprise a relatively small vertical hydrofoil part 15 connected to a substantially horizontal hydrofoil main part 16 as an alternative to hydrofoils 5 having an angle with respect to the horizontal plane. The vertical hydrofoil parts 15 connect to the side hulls 3 in the side hull connection regions CI, C2, the connection regions CI, C2 being situated at a distance H6, for example 3/5 H, from the deck. The central hull connection region C3 is located at a distance H5, for example 3/4 H, from the deck 14. Furthermore, figure 5 shows rudders 13 that are positioned behind the rearward hydrofoils 6 for providing optimal yaw control. The central hull 2 is further shown to be curved upwards at a distance LI from the bow 8, at an angle d with respect to the horizontal plane, d lying in the range of 10-50°, more preferably 10-30°, most preferably being around 15°.

[0035] Thus, the invention has been described by reference to the embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.

Reference numerals

1. Vessel

2. Central hull

3. Side hull

4. Forward deflectors

5. Forward hydrofoil

6. Rearward hydrofoil

7. Keel

8a-8c. Bow portions

9a-9c. Stern portions

10. Main hull

11. Rudder

12. Vertical stem

13. Rudder

14. Deck

15. Vertical hydrofoil part

16. Rearward deflectors

17. Bottom

Claims

1. Vessel (1) having a main hull structure (10) extending in a length direction, comprising a deck (14) and a bottom (17), a central hull (2) having a bow (8, 8a) and two side hulls (3) projecting from the bottom of the main hull structure (10), wherein the planes of symmetry of the side hulls (3) intersect each other in a plane of symmetry of the main hull structure (10) above the deck (14), characterised in that the vessel (1) comprises a pair (4) of forward deflectors (5) extending transversely to the length direction at a distance (HI) from the bottom (17), from a side hull (3) connection region (CI, C2) near a lower end of the side hulls (3) to a central hull (2) connection region (C3) near a mid section of the central hull (2).

2. Vessel (1) according to claim 1, the forward deflectors (5) being of substantially planar shape and extending in a transverse direction at a an angle (βΐ) of between 0 and 45, preferably between 0 and 25 degrees to a horizontal plane.

3. Vessel (1) according to claim 1 or 2, wherein the side hull (CI, C2) and central hull connection regions (C3) are situated at respective distances in the length direction LI, L2 from the bow, the distance LI being larger than the distance L2.

4. Vessel (1) according to claim 3, the bottom of the side hulls (3) extending in a forward region upwards towards deck (14) level near the bow (8), a vertical distance H5 from the deck to the forward deflectors (5) in the forward region being larger than a vertical distance H6 from the deck to the side hull (3) bottoms.

5. Vessel (1) according to any of the preceding claims, the vessel (1) comprising a stern (9, 9a-9c), and a pair (16) of rearward deflectors (6) near the stern (9, 9a-9c) extending transversely to the length direction at a distance (H2) from the bottom (17), from a side hull connection region (CI, C2) near a lower end of the side hulls (3) to a central hull (2) connection region (C3) near a mid section of the central hull (2).

6. Vessel (1) according to claim 5, the rearward deflectors (6) being of substantially planar shape and extending in a transverse direction at an angle (β3) of between 0 and 45, preferably between 0 and 25 degrees to a horizontal plane.

7. Vessel (1) according to claim 5 or 6, the rearward deflectors (6) extending transversely to the length direction.

8. Vessel (1) according to claim 5, 6 or 7, the connection regions (C4, C5, C6) of the rearward deflectors (6) being situated near the bottom of the central hull (2) and of the side hulls (3).

9. Vessel (1) according to one of the preceding claims, wherein the vessel (1) is provided with means for changing the angle of incidence of the deflectors (5, 6).

10. Vessel (1) according to one of the preceding claims, wherein the aspect ratio of the deflectors (5, 6) is high.

11. Vessel (1) according to one of the preceding claims, wherein the side hulls (3) are provided with a pair of keels (7) projecting from the keel portion of the side hulls (3).

12. Vessel (1) according to claim 11, wherein each of the two keels (7) is arranged at an angle of approximately 90° with respect to the forward (5) and/or aft deflector (6) at that respective side of the vessel (1), when viewed along the longitudinal axis thereof.

13. Vessel (1) according to claim 11 or 12, wherein the keels (7) are arranged near the centre portion of the side hulls (3) in longitudinal direction.

14. Vessel (1) according to one of the preceding claims, wherein the central hull (2) has a substantially vertical bow portion (12) extending downwards from the bow to a lower bow point, the bottom of the central hull (2) extending from the lower bow point to a keel level at an angle d between 10 and 50°, preferably between 10 and 30°.

15. Vessel (1) according to one of the preceding claims, wherein the vessel (1) is a sailing yacht.