The present invention relates to improvements in and/or relating to feathering propellers. BACKGROUND OF THE INVENΗON

For use in a number of particularly marine applications, folding or feathering propellers have been utilised.

The ordinary folding propeller often used on cruising yachts have the propeller blades fold so as to provide a low drag froin the propeller when under sail. The disadvantage of such folding propellers (eg as sclosed in US Patent Specification No. 4,086,025) is that the blades may not open when in ahead operation and can cause vibration if not perfectly aligned or true to each other. The most important detriment with this form of changing profile propeller is that motoring efficiency compared to a fixed blade propeller of the same diameter is about 70%. The same type of folding propeller when in astern condition will not open to the maximum diameter due to the thrust on the blades balancing the centrifugal force holding the blades open with the result that seldom is more than 50% of the motoring efficiency is achieved compared to a fixed blade propellers of the same diameter. Moreover even in the feathered condition the propeller and its shaft will auto-rotate thereby increasing drag. In addition, these propellers require significant mass in the tips of the blades to provide the maximum centrifugal force thus constraining optimum blade design and causing vibration problems. In racing yachts this extra mass is a disadvantage.

To address the deficiencies of such folding propellers, a variety of different bladed propellers of a feathering kind have been proposed. Usually these are of two or three blades but can have more. Frequently such feathering propeller blades are fitted with a bevel pinion that engages a central cone gear driven by a shaft. Such arrangements tend to be complex notwithstanding their wide spread acceptance in the boating industry. An example of such a propeller includes that marketed under the trade mark "MAX- PROP"™ available in New Zealand from Marine Power and Service Limited, 50 Cook Street, Auckland 1, New Zealand.

Some feathering propellers are known such as the propeller disclosed in US Patent Specification 4,058,360 which discloses a propeller having blades that when fully feathered are constrained by stops that hold the feathered blades in line with the shaft. Other

feathering propellers such as the MAX-PROP™ cause the blades to turn to and from the pitch position by bevel gears at the base of each blade engaged with a bevel gear on the propeller shaft. Thus the blades are geared together and only face in the same direction (are feathered) when they are in line with the shaft. Blades feathered in that position may cause resistance or drag because in practice the flow of water is not commonly in line with the shaft. For example in order for the propeller shaft to penetrate the hull surface and give adequate clearance for the propeller it is commonly angled down at an angle to the horizontal. Inclinations of between 10° and 20° are known. Also common is an area of the hull immediately above or adjacent the propeller which curves or slopes upwards. As fluid flowing over an object tends to flow parallel to the surface the water flow of the object at or near the propeller is at an angle substantially similar to the angle of the adjacent hull surface. Therefore it is known for example to have a propeller shaft at an angle of 11° to the horizontal but the flow of water parallel to the hull at an angle of 17° to the shaft.

Further problems are encountered with sailing yachts which when sailing against the wind have the longitudinal centre line of the craft offset from the direction of travel by up to 5° or more. This is caused by slippage.

Yet another example is the sailing of a boat in rough weather where the boat is caused to surge sideways with wave action which causes a flow of water across the line of, and therefore, substantially non-parallel to the propeller shaft

When the blades in a feathered condition are substantially parallel to the propeller shaft and the flow of water is substantially not aligned or parallel with the shaft it will cause drag resistance and it may cause the propeller and shaft to auto-rotate, which can cause damaging wear and also indicates that the progress of the vessel is being resisted. This is particularly a problem with three bladed propellers but also occurs with two bladed propellers.

There is a need for an alternative to such gear dependent variable geometry propellers and particularly for feathering propellers and it is to this that the present invention is directed.

The present invention therefore wishes to offer an alternative form of propeller which is an alternative to the existing forms which will at least provide the public with an option and/or advantages.

BRIEF SUMMARY OF THE INVENΗON

In a first aspect the present invention consists in a bladed featherable propeller assembly for fitment or fitted to a drive shaft, said assembly comprising: a hub member or assembly (hereafter "hub assembly") having means enabling fitment to, or fitted to, a said drive shaft so as to rotate with the shaft in each direction of rotation of the shaft, a member, members or assembly (hereafter "blade carrying assembly") carried by and/or axially located by (relative to a said shaft in use) said hub assembly being rotatable relative to said hub assembly (and, in use, said shaft) within relative limits of movement, and at least one pivotally mounted propeller blade mounted from said blade carrying assembly so as to be able to assume each of the following conditions:

(i) a forward driving condition under a forward drive rotation from a said shaft in use, (ϋ) a feathering condition when not under drive from a said shaft in use as a result (at least in part) of the flow of water over the blade, and

(iii) a reverse driving condition under a reverse drive rotation from a said shaft in use, wherein each of conditions (i) and (iii) have said blade carrying assembly and hub assembly at a different said relative limit of movement, wherein said propeller blade(s) in the feathering condition (are) substantially free to substantially move into an orientation which is substantially aligned with the flow of water past said propeller assembly.

Preferably said propeller blades, when in the feathering condition, have a range of movement of approximately + or -30° from the shaft centre line.

Preferably biasing means is provided between said hub assembly and said blade carrying assembly.

Preferably said biasing means biases said blade carrying assembly to one extreme of said blade carrying assembly relative limits.

Preferably said biasing is out from the reverse drive limits. Preferably said extreme of said relative limits is such that said propeller blade mounted from said blade carrying assembly is in a forward driving condition under a forward drive rotation from said shaft in use.

Preferably said biasing means is a coil spring.

Preferably said blade adjacent said blade carrying assembly is shaped so as to in use

fit substantially closely to said hub member or assembly.

Preferably said distal end of said hub member or assembly is substantially (hemi) spherical.

In a further aspect the invention consists in a bladed featherable propeller assembly for fitment or fitted to a drive shaft, said assembly comprising: a hub member or assembly (hereafter "hub assembly") having means enabling fitment to, or fitted to, a said drive shaft so as to rotate with the shaft about the shaft axis in each direction of rotation of the shaft; a member, members or assembly (hereafter "blade carrying assembly") carried by and/or axially located by (relative to a said shaft in use) said hub assembly being rotatable relative to said hub assembly and, in use, said shaft within relative limits of movement; and at least one pivotally mounted propeller blade mounted from said blade carrying assembly; the construction and arrangement being characterised in that:

(i) in a forward driving condition under a forward drive rotation from a said shaft in use, each propeller blade adopts a forward driving pitch by virtue of the trailing regions of the propeller blade causing said blade to move about its pivot with respect to said blade carrying assembly under water pressure to an abutment between said blade (or an extension thereof) and said blade carrying assembly precluding any further pivoting under water pressure while in the forward rotation direction of the propeller,

(ii) a feathering condition when not under drive from a said shaft in use as a result (at least in part) of the flow of water over the blade causing the blade to pivot with respect to the blade carrying assembly (optionally with some relative movement within the relative limits by said blade carrying assembly relative to the hub assembly) to align with the water flow in a reduced drag condition, and wherein said blade(s), in the feathering condition, is (are) free to move over a range of angles with respect to the shaft centre line.

(iii) a reverse driving condition under a reverse drive rotation from a said shaft in use, wherein said hub assembly and said blade carrying assembly

rotate to a different relative condition to that which they are in when in the forward driving condition thereby causing said trailing regions under a sliding and/or pivot-like (or functionally equivalent) abutment with said hub assembly rearwardly of said blade carrying assembly to pivot about said pivot of said blade with the bls e carrying assembly so that said trailing regions of the blade are the leading edge of the blade in the reverse condition and/or the blade has thus been restored against the hydrodynamic forces acting on the blade to the same or similar position as it would occupy in the forward condition under hydrodynamic forces in isolation.

Preferably said range of said angles in (ii) is + or - about 30° from shaft centre line. Preferably biasing means are included between said blade carrying assembly and said hub assembly.

Preferably said biasing means biases said blade carrying assembly to one extreme of said blade carrying assembly relative limits.

Preferably said biasing is out from the reverse drive limits. Preferably said biasing means is a coil spring.

Preferably said blade adjacent said hub assembly is shaped so that said blade adjacent said hub assembly fits closely to said hub assembly. Preferably said hub member has a substantially (hemi) spherical (distal) end.

Preferably said blade disposition (i.e. angle) about the pivotal mounting and relative to said shaft in use is substantially the same (eg within the same quadrant) in each of conditions (i) and (iii).

In yet a further aspect the invention consists in a bladed featherable propeller assembly for fitment or fitted to a drive shaft, said assembly comprising: a hub member or assembly (hereafter "hub assembly") having means enabling fitment to, or fitted to, a said drive shaft so as to rotate with the shaft about the shaft axis in each direction of rotation of the shaft; a member, members or assembly (hereafter "blade carrying assembly") carried by and/or axially located by (relative to a said shaft in use) said hub assembly being rotatable relative to said hub assembly and, in use, said shaft within relative limits of movement; and at least one pivotally mounted propeller blade mounted from said blade carrying

assembly; the construction and arrangement being characterised in that:

(i) in a forward driving condition under a forward drive rotation from a said shaft in use, each propeller blade adopts a forward driving pitch by virtue of the trailing regions of the propeller blade causing said blade to move about its pivot with respect to said blade carrying assembly under water pressure to an abutment between said blade (or an extension thereof) and said blade carrying assembly precluding any further pivoting under water pressure while in the forward rotation direction of the propeller,

(ii) a feathering condition when not under drive from a said shaft in use as a result (at least in part) of the flow of water over the blade causing the blade to pivot with respect to the blade carrying assembly (optionally with some relative movement within the relative limits by said blade carrying assembly relative to the hub assembly) to align with the water flow in a reduced condition, and wherein said blade(s), in the feathering condition, is (are) free to move over a range of angles with respect to the shaft centre line, (iii) a reverse driving condition under a reverse drive rotation from a said shaft in use, wherein torque applied to said shaft causes the blade carrying assembly to rotate about the hub assembly to the reverse rotation stop. Preferably said range of said angles in (ii) is -1- or - about 30° from shaft centre line. Preferably biasing means are included between said blade carrying assembly and said hub assembly.

Preferably said biasing means biases said blade carrying assembly to one extreme of said blade carrying assembly relative limits.

Preferably said biasing is out from the reverse drive limits. Preferably said biasing means is a coil spring. Preferably said blade adjacent said hub assembly is shaped so that said blade adjacent said hub assembly fits closely to said hub assembly.

Preferably said distal end of said hub member or assembly is substantially (hemi) spherical.

In yet another aspect the present invention consists in a bladed featherable propeller assembly for fitment or fitted to a drive shaft, said assembly comprising: a hub member or assembly (hereafter "hub assembly") having means enabling fitment to, or fitted to, a said drive shaft so as to rotate with the shaft about the shaft axis in each direction of rotation of the shaft, a member, members or assembly (hereafter "blade carrying assembly") carried by and/or axially located by (relative to a said shaft in use) said hub assembly being rotatable relative to said hub assembly (and, in use, said shaft) within relative limits of movement, and at least one pivotally mounted propeller blade mounted from said blade carrymg assembly so as to be able to assume each of the following conditions:

(i) a forward driving condition under a forward drive rotation from a said shaft in use, (ii) a feathering condition when not under drive from a said shaft in use as a result (at least in part) of the flow of water over the blade, and (iii) a reverse driving condition under a reverse drive rotation from a said shaft in use, wherein each of conditions (i) and (iii) have said blade carrying assembly and hub assembly at a different said relative limit of movement, wherein biasing means is provided between said hub assembly and said blade carrying assembly. Preferably said propeller blades, when in the feathering condition ie. (ii), have a range of movement of approximately + or -30° from the shaft centre line.

Preferably said biasing means biases said blade carrying assembly to one extreme of said blade carrying assembly relative limits.

Preferably said biasing is out from the reverse drive limits. Preferably said extreme of said relative limits is such that said propeller blade mounted from said blade carrying assembly can turn to the forward driving condition under a forward drive rotation from said shaft and the pressure of water against the blade in use.

Preferably said blade (ie. portion of said blade member) adjacent said hub assembly is shaped so that said portion of said blade adjacent said hub member fits substantially closely.

Preferably said bladed featherable propeller is substantially as hereinbefore described.

Preferably the distal end of said hub member is substantially (hemi) spherical. In yet another aspect the present invention consists in a bladed featherable propeller assembly for fitment or fitted to a drive shaft, said assembly comprising: a hub member or assembly (hereafter "hub assembly") having means enabling fitment to, or fitted to, a said drive shaft so as to rotate with the shaft about the shaft axis in each direction of rotation of the shaft, a member, members or assembly (hereafter "blade carrying assembly") carried by and/or axially located by (relative to a said shaft in use) said hub assembly being rotatable relative to said hub assembly (and, in use, said shaft) within relative limits of movement, and at least one pivotally mounted propeller blade mounted from said blade carrying assembly so as to be able to assume each of the following conditions:

(i) a forward driving condition under a forward drive rotation from a said shaft in use, (ii) a feathering condition when not under drive from a said shaft in use as a result (at least in part) of the flow of water over the blade, and

(iii) a reverse driving condition under a reverse drive rotation from a said shaft in use, wherein each of conditions (i) and (iii) have said blade carrying assembly and hub assembly at a different said relative limit of movement, wherein said blade(s) adjacent said blade carrying assembly is (are) shaped so as to, in use, fit substantially closely to said blade carrying assembly.

Preferably said bladed featherable propeller is substantially as hereinbefore described.

In some forms of the invention the "hub assembly" may carry the blade carrying assembly between spaced parts thereof (to prevent substantial axial displacement relative to a said drive shaft), the blade carrying assembly having a bearing type association with said shaft. Indeed the shaft could use a shoulder to coact with a form of hub assembly to "sandwich" axially (relative to the shaft) the propeller carrying member.

Preferably, as described hereinafter, the hub assembly is also interposed between said blade carrying assembly and either the shaft or the axis of the shaft.

Preferably said blade carrying assembly carries two or three blades but can if desired carry more.

Preferably said stop or other means of outwardly directed protrusion is from the

blade carrying assembly of the hub assembly itself, the blade carrying assembly preferably being in the form of a collar held relative thereto but in the appropriate rotational relationship i.e. at its appropriate limit.

Preferably the arrangement is substantially as hereinafter described with reference to any of the accompanying drawings.

In yet a further aspect the present invention consists in a bladed featherable propeller assembly substantially as hereinafter described with reference to any one or more of the accompanying drawings.

In yet a further aspect the present invention consists in combination a propeller assembly in accordance with the present invention and a shaft engaged with said hub assembly thereof.

Preferably said shaft is that of a boat.

The propeller can be for either right or left handed drive rotations, i.e. handedness forms no part of the invention. The invention consists in the foregoing and also envisages constructions of which the following gives examples. BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a side sectional view through the section A-A (as shown in Figure 2);

Figure 2 is a front view of the feathered propeller of Figure 1;

Figure 3 is the section B-B looking forward with respect to Figure 1;

Figure 4 shows a plan view of a propeller of the present invention on a shaft;

Figure 5 shows a form of the invention having 2 blades mounted on the hub; and Figure 6 shows a form of the invention having 3 blades mounted on the hub.

DETAILED DESCRIPTION

In a form of the present invention a hub assembly 2 is mounted directly or indirectly on a shaft 1. In preferred forms of the invention this is the propeller shaft of a boat and preferably a yacht. Blade carrying assembly 3 is carried by and/or axially located by relative to shaft 1 in use by said hub assembly 2. In preferred forms of the invention the hub member 2 is fixed on shaft 1 by means of a key 10 and shaft nut 7.

However other forms of fixing are envisaged. Preferably the nut 7 is locked with a split pin (not shown) marked between the nut and the hub assembly.

The blade carrying assembly 3 is rotatable relative to said hub assembly 2 and therefore in use said shaft 1 within relative limits of movement. The limits of movement may be provided by for example a dog clutch or other means of limiting the relative motion of one member to another. Blades and shafts 12 may have a screw thread to allow forced rotation of the blade while restraining the blades centrifugally.

Mounted from said blade carrying assembly 3 in a form of the invention as shown in, for example Figure 5, are two propeller blades 5 and 6, the said propeller blades may be mounted from said blade carrying assembly by means of a shaft or pin 12. In other forms of the invention there may be 3 blades, as shown in Figure 6, or more blades. The provision of more blades limits the amount of movement available to the blades when in the feathered condition, this may provide a limit on the number of blades which are desirable.

In preferred forms of the invention the ends of the propeller blades 5 and 6 adjacent the hub assembly 2 and blade carrying assembly 3 that is the area of the blades 5 and 6 adjacent the pin or shaft 12 is shaped so as to fit closely against said hub assembly 2 and/or said blade carrying assembly 3. Present on said hub assembly 2 are in one form of the present invention are abutments 14. These abutments provide a pivot about which the blades 5 and 6 rotate and slide into the reverse position. These abutments may be in the form of pins or extensions of the hub assembly 2. The abutments 14 may or may not be adjustable. For example, in forms of the invention the abutments 14 may take the form of a nut attached to a threaded stud the provision of different sized nuts provided for adjustment of the abutment 14. If the abutment is in the form of a pin it may be repositioned so as to provide adjustment As can be seen in Figure 4 the abutments 14 are shaped and configured so as to provide a gap 50 between the propeller blades 5 and 6 in the condition wherein they are fully in line with the shaft and the position wherein the propellers 5 and 6 abut said abutments 14. This gap 50 allows the propeller blades 5 and 6 some freedom of rotation so that they are able, within the limits provided by the abutments 14, to pivot so as to be substantially aligned with the direction of fluid flow over said blades.

In a form of the present invention as shown in Figures 2 and 4 stops 13 are provided. These stops are provided on the blade carrying assembly 3 and define the stop position for the blade in the forward and/or reverse driving positions. In forms of the

invention these stops 13 may be adjustable by for example the use of pins insertable into a variety of holes, or other forms of adjustable or moveable stops. For example, in the form of the invention as shown in the figures the blade carrying assembly 3 consists of two members 93 and 94. The members 93 and 94 are joined and held in position relative to each other by pin 100. In forms of the invention the members 93 and 94 may be repositioned relative to each other, thus repositioning the stops 13 by relocating the pin 100. The relationship between the blades 5 and 6 and the stop 13 may also be made adjustable by a grub screw 15 within each of the said blades. This grub screw 15 may be self locking in the preferred form of the invention which utilises nylon blades. The pitch of any blade, when in the forward driving condition is therefore adjustable, by means of changing the length of screw 15 protruding.

The limits to the relative movement of the blade carrying assembly 3 about the hub assembly 2 is in one form of the present invention provided for by a dog clutch arrangement between said blade carrying assembly 3 and said hub member 2. This is as shown in Figure 3 whϊ .s a sectional view through BB of Figure 1.

Figure 1 is a sec-, ial side view of one form of the present invention wherein a biasing means 51 is pr vided between said hub assembly 2 and said blade carrying assembly 3. This biasing means 51 is as in the lorm of the invention illustrated in Figure 1 a coil spring and biases the relative movement between the hub assembly 2 and the blade carrying assembly 3 to one extreme of the relative motion provided for by the dog clutch between said hub assembly 2 and said blade carrying assembly 3. Thus the propeller blades 5 and 6 are biased towards the forward driving condition.

In preferred forms of the invention the biasing means 51 in the form of a coil spring is produced from corrosion protected steel. It can be seen in at least Figures 1 and 2 that the blades 5 and 6 are shaped so as the gap 60 between said blades and said hub assembly 3 is small. The gap 60 must of course be sufficiently large so as to allow the blades 5 and 6 to rotate freely and also allow the blades to pass over any irregularities that may be present on the hub assembly and/or blade carrying assembly. In an especially preferred form of the invention the end of the hub and/or hub assembly 2 is substantially spherical and the portion of the blades or blade assemblies 5 and 6 adjacent the hub or hub assembly 2 are thus substantially semicircular.

The hub member, blade member(s) and the various stops and abutments are

preferably produced from suitable corrosion protected or resistant materials which are known in the art to which the invention relates. In forms of the invention the propeller blades may be made from a suitable grade of nylon.

Figure 4 is a plan view of one form of the invention shown in Figure 1. The blade 5 is free to swing in the arc 20 between the pitch stop 13 and the abutment 14. Thus when not being driven in either forward or reverse directions by the shaft 1 it is free to align with the water flow which does not necessarily align with the shaft 1.