Outboard motor lift plate

Abstract

An outboard motor lift plate adapted for attachment to a cavitation plate of the outboard motor, the lift plate comprising a fore portion and an aft portion, both providing different roles but working together to achieve the best result. The aft portion with the raised risers and reverse tapered winglets achieve incredible stability and handling features and reduced drag. The fore portion is raked relative to the aft section, the 3 degree rake provides an increased amount of extra lift to accelerate the boat on to the plan quicker and maintain the plan at lower speeds. Providing increased performance, reduced fuel consumption and less airborne water spray from a more controlled deflection.

Description

[0001] OUTBOARD MOTOR LIFT PLATE

[0002] Technical Field

[0003] Embodiments relate to an outboard motor lift plate and, in particular, an outboard motor lift plate which may be used in conjunction with a cavitation plate.

[0004] Background

[0005] Boats suffer from cavitation or ventilation issues with air being drawn into the propeller whilst planning. Unbalanced boats cause the outboard motor to struggle to obtain engine RPM due to a longer planing time. Eliminating porpoising and handling issues. It is therefore know to provide outboard motors with a separate anti-cavitation plates, planing foils or lift plates which may be attached to the outboard motor cavitation plate to aid in the boats performance and reduce the issues.

[0006] Summary of the Disclosure

[0007] An embodiment provides an outboard motor lift plate adapted for attachment to a cavitation plate of the outboard motor, the lift plate comprising a fore portion and an aft portion wherein the aft portion is at least partially planar, and wherein at least a portion of the fore portion is raked relative to the aft portion to provide lift when a boat to which the outboard motor is attached moves forward through water.

[0008] The rake of the fore portion may be downwards relative to a propeller of the outboard motor when moving from fore to aft. The lift plate may be adapted to connect to the outboard motor at a location between the propeller and the hull of the boat, when the lift plate is installed for use.

[0009] The aft portion may comprise a central plate.

[0010] The fore portion may comprise two lateral winglets, wherein the two lateral winglets are attached to the central plate by risers so that the lateral winglets are raised relative to the central plate and wherein the risers are shaped to thereby rake the winglets upwards when considered in a forward direction of the boat.

[0011] The risers may describe a wedge shape.

[0012] The winglets may extend into the aft portion in a direction substantially parallel to the central plate. The risers may extend into the aft portion with constant height so that the winglets, in the aft section, are substantially parallel to the central plate.

[0013] The central plate may extend into the fore section. The central plate in the fore section may provide an attachment for the lift plate to the outboard motor.

[0014] The lift plate may be configured so that a dividing line between the fore portion and the aft portion of the lift plate may, when the lift plate is installed, be located in line with a propeller of the outboard motor.

[0015] A rake angle of the winglets may be between 2 and 5 degrees.

[0016] The risers may raise the winglets relative to the central plate between 15 and 55 mm.

[0017] A fore portion of each winglet may be tapered. The fore portion of each winglet may be tapered at a taper angle of 13 to 18 degrees.

[0018] The lift plate may be constructed from a sheet material. The sheet material may have substantially constant thickness through-out the lift plate. The sheet material may be stainless steel, fibre glass, aluminium, a hard plastic or any other suitable material.

[0019] The lift plate may be provided as an integral unit formed from a single piece of sheet material. In a further embodiment, the lift plate may be provided as separate parts connected to one another, e.g. by welding.

[0020] Description of the Drawings

[0021] Embodiments are herein described, with reference to the accompanying drawings in which:

[0022] Figure 1 is a top perspective view illustrating a lift plate according to an embodiment attached to an outboard motor;

[0023] Figure 2 is a bottom perspective view of the lift plate of Figure 1;

[0024] Figure 3 is a rear view of the lift plate of Figure 1;

[0025] Figure 4 is a top view of the lift plate of Figure 1 prior to installation;

[0026] Figure 5 is a side view of the lift plate of Figure 1 showing the outboard motor in dashed lines; Figures 6 to 8 are schematic diagrams showing how a lift plate according to an embodiment operates; and

[0027] Figure 9 illustrates a comparison of an lift plate of an embodiment compared to an lift plate known in the art.

[0028] Detailed Description of Specific Embodiment

[0029] Embodiments provide an outboard motor lift plate comprising a fore portion and an aft portion wherein the aft portion is at least partially planar to reduce cavitation, more controlled stability and lift and wherein the fore portion is raked relative to the aft portion to provide additional lift when a boat to which the outboard motor is attached moves forward through water. A planar aft portion and a raked fore portion may allow embodiments to assist in planning of the boat as the boat moves by providing lift.

[0030] Embodiments may increase the lift to plane faster and maintain the plane at a lower speed, thereby potentially increasing performance, reducing fuel consumption, eliminating porpoising and may reduce airborne water spray due to more controlled deflection compared to known plates.

[0031] The fore portion may comprise two lateral winglets, wherein the two lateral winglets are attached to the central plate by risers so that the lateral winglets are raised relative to the central plate. By providing additional lift with two raised lateral winglets, once lift has been achieved, these winglets may be raised out of the water to thereby reduce drag created due to the rake of the winglets.

[0032] A fore portion of each winglet may be tapered. This may contribute to hydrodynamic efficiency. Furthermore, since the winglets are raked, providing a raked fore portion of each winglet may avoid unnecessary drag and improve the overall lift provided.

[0033] The risers and the taper angle may act to trap the water in and make it harder for the water to slide off the plate having more control and hence more stability.

[0034] The lift plate may be made as an integral whole and may be constructed from a sheet material. This may provide a lift plate which is efficient and cost-effective to manufacture.

[0035] Figure 1 illustrates an outboard motor lift plate 10 according to an embodiment. The same lift plate 10 is shown in various views in Figures 2 to 6. Figures 1, 2 and 5 illustrate the lift plate 10 installed on an outboard motor 12 comprising an anticavitation plate 14 and propeller 16.

[0036] The lift plate 10 comprises an aft portion 20 and a fore portion 22, as illustrated in Figures 1 and 4. The aft portion 20 comprises a planar plate 24 which is located above the propeller 16. By being located above the propeller 16, the planar plate 24 may assist in reducing cavitation of the propeller 16. The fore portion 22 comprises two winglets 26 and 28 located laterally and situated on either side of the outboard motor 12.

[0037] The planar plate 24 of the aft section 20 extends forwards into the fore portion 22 where it is provided with a central, V-shaped aperture 30 (Figure 4) which is shaped to accommodate the casing of the outboard motor and which allows the winglets 26 and 28 to be located on either side of the outboard motor 12. In this embodiment, the fore portion of the planar plate 24 is provided with apertures 32 (Figure 4) through which bolts 34 (Figure 1) pass to attach the lift plate 10 to the cavitation plate 14 of the outboard motor 12 with nuts 36 attached to the bolts 34 (Figures 2 and 3).

[0038] The winglets 26 and 28 are attached to the planar plate 24 by respective risers 38 and 40. The risers 26 and 28 are shaped as wedges thereby providing the winglets 26 and 28 with a rake. In other words, a leading edge of each winglet is raised relative to a training edge or portion.

[0039] The rake of the winglets 26 and 28 is illustrated in Figure 5 which is a side view. As shown the riser 40 describes a wedge shape thereby raising the fore of the winglet 28 relative to an aft of the winglet 28. The rake angle is the angle between the planar plate 24 and the inclined surface of the winglet 28 where this meets the riser40, designated 0 in Figure 5.

[0040] The taper angle may be chosen to suit the operating characteristics concerned such as the size and shape of the boat and outboard motor concerned. It was been found that in certain embodiments rake angles between 2 and 5 degrees may be preferable.

[0041] As best illustrated in Figure 4, the winglet 26 has a tapered fore portion 42. Winglet 28 has a corresponding tapered fore portion 44. Since the fore portion of each winglet is also the raised portion relative to forward motion, the tapered fore portions of the winglets may reduce drag and create lift gradually over the surface of the winglets. The angle of the taper is, as shown in Figure 4, designated cp. In this embodiment, the angle cp is 15 degrees, but it is to be realised that many other angles are possible too. In certain embodiments, the taper angle may be between 13 and 18 degrees.

[0042] As further illustrated, each of the winglets 26 and 28 extend back to the aft portion 20 of the lift plate 10. The fore portion of each winglet 26, 28 is raked whereas the aft portion is parallel to the planar plate 24. The risers 38 and 40 extend back into the aft portion too. Therefore, the aft portion of the winglets 26 and 28 are raised relative to the planar plate 24. The aft portions of the winglets 26 and 28 may contribute to providing downward pressure to assist in more controlled stability and avoiding cavitation by extending laterally over and / or aft of the propeller.

[0043] As shown in Figure 4, and in other Figures, line 50 is included to illustrate the demarcation between the aft portion 20 and the fore portion 22. However the line 50 is an imaginary line and does not denote a physical characteristic of the lift plate 10.

[0044] Without wishing to be tied to theory, the inventors believe that embodiments operate in the following manner.

[0045] As the boat 110 moves forward through the water, the casing of the outboard motor 112 drags through the water and creates a water reserve with vortices V. The raked fore portion 104 of the lift plate 100 interacts with this water reserve generating increased lift. As illustrated in Figure 6.

[0046] With reference to Figure 7, as the speed of the boat 110 increases, the lift increases and the position of both the outboard motor 112 and boat 110 are raised relative to the water. Raising of the boat and motor will also raise the lift plate 100 with the result that less of the raked fore portion 104 engages with the water and results in less airborne spray as it has a more controlled deflection.

[0047] Figure 8 illustrates the boat at full speed. At this speed, the water will engage with little or no part of the raked fore portion reducing drag, providing increased performance and less airborne spray as it has a more controlled deflection 104 and the planar aft portion 102 is still providing downward pressure to provide stability and reduce cavitation by reducing turbulence in the area directly surrounding the propeller 114.

[0048] Figure 9 is a comparison between the operation of an embodiment of this disclosure 94, 96 and 98 compared to a lift plate known in the art 95, 97 and 99. Comparing 94 and 95 which illustrate the operation at a 5 degree trim angle, the back half of the plate B provides downward pressure on the water. The leading edge A has reduced or no pressure as it leaves the water column, potentially dramatically reducing drag, increasing performance and top speed. There is less airborne water spray as the plate of an embodiment 94 has a more controlled deflection than the known plate 95

[0049] Comparing 96 and 97 which illustrate the operation at a 0 degree trim angle, the rake on the leading edge A increases the downward pressure on the water which increases lift and acceleration out of the water, compared to the known plate 97 potentially reducing fuel consumption and increasing performance. Here too, there may be less airborne water spray due to a more controlled deflection compared to the known plate 97.

[0050] Comparing 98 and 99 which illustrate the operation at a -8 degree trim angle,

[0051] The design 98 of the plate with 2 to 5 degree rake angle according to an embodiment may have increased the lift and the ability to accelerate out of the water and onto the plane. This in turn, may result in lower planning speeds, increase performance, reduce fuel consumption, provide greater stability and provide less airborne water spray as it may have a more controlled deflection than the known plate 99.

[0052] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

[0053] In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments. Similarly, the word “device” is used in a broad sense and is intended to cover the constituent parts provided as an integral whole as well as an instantiation where one or more of the constituent parts are provided separate to one another.

Claims

Claims1. An outboard motor lift plate adapted for attachment to a cavitation plate of the outboard motor, the lift plate comprising a fore portion and an aft portion wherein the aft portion is at least partially planar, and wherein at least a portion of the fore portion is raked relative to the aft portion to provide lift when a boat to which the outboard motor is attached moves forward through water, wherein the aft portion comprises a central pate and wherein the fore portion comprises two lateral winglets attached to the central plate by risers so that the lateral winglets are raised relative to the central plate and wherein the risers are shaped to thereby rake the winglets upwards relative to the central plate when considered in a forward direction of the boat, wherein the risers raise the winglets out of the water once said lift is attained.

2. The lift plate of claim 1 wherein the rake of the fore portion is downwards relative to a propeller of the outboard motor when moving from fore to aft.

3. The lift plate of claim 1 or claim 2 adapted to connect to the outboard motor at a location between the propeller and the hull of the boat, when the lift plate is installed for use.

4. The lift plate of any preceding claim wherein a rake angle of the winglets is between 2 and 5 degrees.

5. The lift plate of any preceding claim wherein the risers describe a wedge shape.

6. The lift plate of any preceding claim wherein the risers raise the winglets relative to the central plate between 15 and 55 mm.

7. The lift plate of any preceding claim wherein the winglets extend into the aft portion in a direction substantially parallel to the central plate.

8. The lift plate of claim 7 wherein the risers extend into the aft portion.

9. The lift plate of any preceding claim wherein the central plate extends into the fore section.

10. The lift plate of claim 9 wherein the central plate in the fore sectionprovides an attachment for the lift plate to the outboard motor.

11. The lift plate of any preceding claim configured so that a dividing line between the fore portion and the aft portion of the lift plate may, when the lift plate is installed, is located in line with a propeller of the outboard motor.

12. The lift plate of any preceding claim constructed from a sheet material.

13. The lift plate of any preceding claim wherein the lift plate is provided as an integral unit formed from a single piece of sheet material.

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