Crane, system and method for lifting objects and generating propulsion for a vessel

Abstract

A crane (100, 100') for mounting on a vessel to provide lifting operations on the vessel and propulsion to the vessel, comprising: a mast (200, 200') comprising a first wing portion; and a boom (300, 300') comprising a second wing portion; wherein the crane (100, 100') is moveable between a sailing position and an operational position; wherein in the sailing position the mast (200, 200') and boom (300, 300') are substantially vertical and together the first wing portion and second wing portion form a complete wing; and in the operational position the mast (200, 200') is substantially vertical and the boom (300, 300') is tilted relative to the mast (200, 200') such that the boom (300, 300') can be used to lift an object; such that in use in the sailing position the crane (100, 100') can provide propulsion to the vessel to which the crane (100, 100') is mounted and in the operational position the crane (100, 100') can lift or lower an object.

Description

[0001] CRANE, SYSTEM AND METHOD FOR LIFTING OBJECTS AND GENERATING PROPULSION FOR A VESSEL

[0002] FIELD

[0003] The present invention relates to a crane. More particularly, the present invention relates to a crane for lifting objects on a vessel and also providing propulsion or supplementary propulsion to the vessel.

[0004] BACKGROUND

[0005] Cranes are used in myriad lifting operations both onshore and offshore. In offshore operations, the cranes are typically installed on a deck and serve to lift and move heavy objects such as containers or oilfield equipment for example.

[0006] Typically there are a minimal number of cranes installed on a vessel as they are expensive pieces of equipment and are expensive to install and maintain. Furthermore, they take up a large working area on board the vessel on which they are installed.

[0007] Crane design for vessels is plagued by many conflicting design requirements. It is often desirable to provide cranes which can lift objects to a sufficiently useful height and / or have a sufficiently useful span / reach. However, cranes typically stand tall on the deck of a vessel and can often be the highest point on the vessel. Therefore, it is desirable to minimise the height of the crane such that the vessel can easily pass under bridges, for example.

[0008] There is also a constant strive towards efficient use of fuel, particularly in heavy industries where a lot of fuel is consumed such as in shipping. To reduce the amount of fuel required, the vessel can either be made more efficient, such as by improving the vessel aerodynamics, or the vessel engine propulsion can be replaced by free energy sources such as wind power, i.e. by replacing engine propulsion by use of a sail. Unfortunately, sails are not commonly used in shipping applications as the main propulsion source or even as a supplementary propulsion source, mostly due to the power required but also due to the unpredictability of the wind source.

[0009] Furthermore, many industrial vessels have no available deck space for the provision of sails.

[0010] The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to the prior art.

[0011] The object is achieved through features, which are specified in the description below and in the claims that follow.

[0012] SUMMARY

[0013] According to a first aspect of the invention, there is provided a crane for mounting on a vessel to provide lifting operations on the vessel and propulsion to the vessel, comprising: a mast comprising a first wing portion; and a boom comprising a second wing portion; wherein the crane is moveable between a sailing position and an operational position; wherein in the sailing position the mast and boom are substantially vertical and together the first wing portion and second wing portion form a complete wing; and in the operational position the mast is substantially vertical and the boom is tilted relative to the mast such that the boom can be used to lift an object; such that in use in the sailing position the crane can provide propulsion to the vessel to which the crane is mounted and in the operational position the crane can lift or lower an object.

[0014] The complete wing may comprise an under camber wing profile.

[0015] The complete wing may be substantially symmetrical in profile about a plane of symmetry bisecting a chord line of the complete wing.

[0016] The crane may further comprise: at least one luffing cable connecting the mast to the boom and configured to raise and lower the boom in operation; and at least one lifting cable connected to the boom and configured to raise and lower an object in operation.

[0017] The crane may further comprise: at least a first winch configured to reel in and out the luffing cable; and at least a second winch configured to reel in and out the lifting cable.

[0018] In the sailing position the mast and boom may be releasably attached together.

[0019] In the sailing position the first wing portion and second wing portion may together form a continuous surface.

[0020] The boom may comprise a recess or aperture such that the mast is received within the recess or aperture when the crane is in the sailing position.

[0021] The mast may be connected to a foundation block. The foundation block may be configured to rotate in a swivel on the deck of a vessel in use.

[0022] The mast and foundation block may be integrally formed.

[0023] The boom may be configured to be moveable to a substantially horizontal position in use.

[0024] The boom may be pivotally releasably mounted to the mast. The boom portion may further comprise an adjustable flap configured to adjust the camber of the wing in use to optimise the propulsion provided.

[0025] According to a second aspect of the invention, there is provided a system configured to provide lifting operations and propulsion on a vessel, the system comprising: a vessel; and a crane according to the first aspect of the invention rotatably mounted on the vessel.

[0026] According to a third aspect of the invention, there is provided a method of optimising the propulsion provided to a vessel, comprising the steps of: providing a system according to the second aspect of the invention; moving the crane to the sailing position; and locating the system in a wind stream such that the crane provides propulsion to the vessel.

[0027] According to a fourth aspect of the invention, there is provided a use of a system according to the second aspect of the invention to provide propulsion to the vessel.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] An embodiment of the invention will now be described with reference to the following drawings, in which:

[0030] Figure 1 shows a first exemplary crane for providing lifting operations and propulsion in a sailing position;

[0031] Figure 2 shows the crane of Figure 1 moving to an operational position;

[0032] Figures 3 and 4 show the crane of Figure 1 in an operational position;

[0033] Figures 5 to 8 shows detailed views of the crane of Figure 1 in the sailing position;

[0034] Figures 9 shows the crane of Figure 1 in the operational position;

[0035] Figures 10 and 11 show detailed views of the crane of Figure 1;

[0036] Figures 12 and 13 show cross-sectional views through the crane of Figure 1 ;

[0037] Figure 14 shows a detailed view of the mast of the crane of Figure 1 in the operational position;

[0038] Figure 15 shows a detailed view of the boom of the crane of Figure 1 in the operational position;

[0039] Figure 16 shows a detailed view of the lifting winch of the crane of Figure 1 ;

[0040] Figure 17 shows a plan view of the crane of Figure 1 in the sailing position;

[0041] Figure 17a shows an alternative wing profile for use with the crane of Figure 1 ;

[0042] Figure 18 shows a bottom view of the crane of Figure 1 in the sailing position; Figure 19 shows a second exemplary crane in the sailing position;

[0043] Figures 20 and 21 show alternative views of the crane of Figure 19 in the sailing position;

[0044] Figure 22 shows the crane of Figure 19 in the operational position;

[0045] Figures 23 and 24 show detailed views of the crane of Figure 19 in the sailing position;

[0046] Figures 25 and 26 show cross-sectional views through the crane of Figure 19; Figure 27 shows a plan view of the crane of Figure 19 in the sailing position; Figure 27a shows an alternative wing profile for use with the crane of Figure 19;

[0047] Figure 28 shows a bottom view of the crane of Figure 19 in the sailing position;

[0048] Figure 29 shows an exemplary propulsion plot;

[0049] Figure 29a shows a vessel travelling into a headwind with the crane provided in a position to reduce drag;

[0050] Figure 29b show a vessel travelling with a tailwind with the crane provided in a position to produce propulsion; and

[0051] Figures 29c and 29d each show a vessel travelling with a sidewind with the crane provided in a position to produce propulsion. For clarity reasons, some elements may in some of the figures be without reference numerals. A person skilled in the art will understand that the figures are just principal drawings. The relative proportions of individual elements may also be distorted.

[0052] DETAILED DESCRIPTION OF THE DRAWINGS

[0053] Figures 1 to 4 show schematic drawings of a first example of a crane 100 for mounting on a vessel (not shown) to provide lifting operations on the vessel and propulsion to the vessel. It will be understood that by providing propulsion to the vessel, it is meant that useful propulsion is provided, i.e. propulsion which has an effect on the overall power requirements for movement of the vessel. The skilled person will be aware that such vessels that are capable of hosting cranes, such as the crane 100 shown in Figure 1 , are generally large and require a substantial amount of energy for manoeuvring and travel. The useful propulsion provided need not entirely be the primary propulsion means of the vessel, however it will be understood that useful propulsion would at least supplement the propulsion provided by the primary propulsion means to a non-negligible extent. The crane 100 comprises major components of a mast 200 and a boom 300. The crane 100 is moveable in use between a sailing position (shown in Figure 1) and an operational position (shown in Figures 3 and 4). Figure 2 shows the crane 100 moving from the sailing position to the operational position.

[0054] Although not shown in the Figures, the crane 100 is for mounting on a sea going vessel. The crane 100 is rotatably attached to the vessel by means of a pedestal I foundation block 400 which can rotate / slew in a swivel on the deck of the vessel.

[0055] The crane 100 further comprises a hoisting winch (not visible in Figures 1 to 4) located on the boom 300 for reeling in and out a lifting cable 500 used to perform hoisting operations.

[0056] The mast 200 is arranged in a vertically upstanding configuration in the sailing position and the operational position. For the avoidance of doubt, the mast 200 is also vertically upstanding when moving between the sailing and operational positions. A luff cable 600 connects the mast 200 to the boom 300 and is reeled in and out by a luff cable winch 700 to allow the boom 300 to be lifted and lowered in use.

[0057] When in an operational position shown in Figures 3 and 4, the crane 100 is ready to perform a hoisting operation by attaching a component to be lifted to the lifting cable 500 and reeling it in using the hoisting winch (not visible in Figures 1-4). It will be understood that myriad possible lifting operations may be performed. In some lifting operations, the crane 100 may rotate on the swivel on the deck of the vessel. In this operational position, useful propulsion is not provided by the crane 100.

[0058] It will be appreciated that the particular type of crane 100 shown in the Figures is merely an example of a possible crane with which the presently described invention finds particular utility. The presently described invention may however be used with myriad crane types, as will become apparent in due course.

[0059] Figure 5 shows a detailed view of the first exemplary crane 100 in the sailing position from a front side of the crane 100. On the front side of the crane 100, the mast 200 and boom 300 together form a convex surface. In the presently described preferred example, the mast 200 and boom 300 together form a flush and continuous surface. As will be understood in due course, the flush and continuous convex surface formed by the mast 200 and boom 300 optimises the aerodynamic performance of the crane 100 when in the sailing position shown in Figure 5. In this sailing position, useful propulsion may be generated by the crane 100. It will be understood that as the crane is moved from the operational position to the sailing position, the crane’s ability to generate useful propulsion is reinstated. On the other hand, when the crane is moved from the sailing position to the operational position, the crane’s ability to generate useful propulsion is removed.

[0060] Figure 6 shows a detailed view of the crane 100 in the sailing position from a rear side of the crane 100. On the rear side of the crane 100, the mast 200 and boom 300 together form a concave surface. In the presently described preferred example, the mast 200 and boom 300 together form a flush and continuous surface. As will be understood in due course, the flush and continuous concave surface formed by the mast 200 and boom 300 optimises the aerodynamic performance of the crane 100 when in the sailing position shown in Figure 6. As will be explained in more detail later, the boom 300 comprises a cover 310 under which further useful components of the crane 100 are housed.

[0061] As will now be apparent, the mast 200 comprises a first wing portion and boom 300 comprises a second wing portion. When the mast 200 and boom 300 are arranged together in the sailing position, the mast 200 and boom 300 form a complete wing. When the complete wing is formed, useful propulsion can be provided by the complete wing to the vessel. In the presently described examples the complete wing comprises an undercamber profile. It will be understood that in other examples other wing profiles may be used.

[0062] In the present description the term wing is used to refer to an aerofoil. Although there are many terms used in the arts of aerodynamics, aerospace and marine engineering, the term wing is herein used to mean a cross-sectional shape which when subjected to a gas stream is capable of generating lift. In the context of marine vessels, wings are used as sails by positioning the wing in a vertical manner, rather than a horizontal manner as they are presented in aircraft. By positioning in said vertical manner, the lift generated by the wing can be used to provide propulsion to the vessel, thereby acting as a sail.

[0063] In the present context, the gas stream (i.e. wind / air) is provided across the crane 100 when the crane 100 is in the sailing position such that the complete wing, formed by first wing portion and second wing portion, receives an air stream such that lift is generated across the complete wing. As explained above, since the complete wing is arranged in a vertically upstanding manner on the vessel, lift generated then acts as a propulsion force for the vessel.

[0064] As will be explained in more detail later, in the presently described example, the wind direction may be from either side of the wing when in use. That is to say, when the crane 100 is arranged on a vessel such that the front side of the crane 100 (shown in Figure 5) faces towards the forward side of the vessel and the crane 100 is in the sailing position, the crane 100 may be exposed to wind from the starboard or port side of the vessel and the crane 100 may generate lift forwards. This may allow the crane 100 to provide propulsion to the vessel when wind is provided from either the starboard side or the port side of the vessel.

[0065] As can be seen most clearly in Figure 6, in the presently described preferred example, the complete wing is symmetrical about a plane of symmetry bisecting a chord line 800 of the complete wing. In the presently described example, the complete wing is symmetrical, however it will be understood that in alternative examples (not shown) the complete wing may be substantially symmetrical in profile such that the complete wing can generate lift when exposed to an airflow from either side of the complete wing.

[0066] It may be advantageous to provide a complete wing which can generate lift when exposed to an airflow from either side, as this may allow the crane 100 to provide propulsion to the vessel when wind is provided from either the starboard or port side of the vessel.

[0067] Although not shown in the Figures, the complete wing may comprise an adjustable flap, or a plurality of adjustable flaps, configured to be adjusted to change the profile of the complete wing to adjust the lift generated. In some examples, the adjustable flap, or plurality of adjustable flaps, may be configured to adjust the profile of the complete wing while maintaining the complete wing substantially symmetrical about a plane of symmetry bisecting the chord line 800. For example, the adjustable flap, or plurality of adjustable flaps, may be used to increase of decrease the camber of the complete wing, when adjustment is desirable. When such adjustment may be desirable is not described in detail here in the interest of brevity, as it will be apparent to a person skilled in the art.

[0068] Still referring to Figure 6, it can be seen that the mast 200 comprises side support members 210, 211 extending outwardly from the bottom of the mast 200. The side support members 210, 211 extends out of a side of the bottom of the mast 200 opposite the boom 300. The crane 100 further comprises a mast support cable 900 connecting the top of the mast 200 to the side support members 210, 211 and the bottom of the pedestal I foundation block 400.

[0069] The described arrangement of the lifting cable 500, luff cable 600, mast support cable 900 and side support members 210, 211 form a particularly advantageous arrangement. That is, the described arrangement provides compressive forces through the crane 100 rather than bending or torsional forces. It will be apparent to a person skilled in the art that bending or torsional forces may not be entirely eliminated but that the described arrangement may provide reduced bending and / or torsional forces.

[0070] It is highly desirable to reduce bending and / or torsional forces on crane components. Compressive forces through the crane 100 structure are easier to manage than bending and / or torsional forces. Therefore, it is desirable to reduce bending and / or torsional forces even if this results in an increase in compressive forces.

[0071] Referring now to Figure 7, the crane 100 is shown again in the sailing position however the cover 310 has been removed from view from the upper portion of the crane 100 so the internal arrangement of the boom 300 is visible. In this connection, as previously discussed, the crane 100 comprises a hoisting winch 710 located on the boom 300 for reeling in and out a lifting cable 500 used to perform hoisting operations. In the presently described example, the hoisting winch 710 is located in a recessed portion within the boom 500.

[0072] In this connection, it may be said that the hoisting winch 710 is located in or on the boom 500. It will be easily understood that, to optimise the aerodynamic profile of the hoisting winch 710 and associated lifting cable 500 are housed behind the cover (visible in Figures 6 and 10, not visible in Figure 7). The cover 310 may serve to provide a smoother and therefore more aerodynamic profile than if the hoisting winch 710 and lifting cable 500 were exposed to airflow in use.

[0073] Figure 8 shows a detailed view of the crane 100 such that the luff cable winch 700, side support members 210, 211 and mast support cable 900 can be seen more clearly.

[0074] Referring now to Figures 9, the crane is shown in the operational position. In this position the crane 100 is ready to perform a hoisting operation by attaching a component to be lifted to the lifting cable 500 and reeling it in using the hoisting winch 710. It will be understood that myriad possible lifting operations may be performed. Although not visually shown in the Figures, the reader is reminded that in the operational position the crane 100 may rotate on the swivel on the deck of the vessel. It will be easily understood that the luff cable 600 in conjunction with the luff cable winch 700 can be used to luff the boom 300.

[0075] As can clearly be seen in Figure 9, when the crane 100 is in the operational position shown, the first wing portion (formed of the mast 200) and the second wing portion (formed of the boom 300) are not together and therefore do not form a complete wing. When the crane is in the operational position, the crane’s ability to generate useful propulsion is removed.

[0076] When performing lifting operations in the operational position shown in Figure 9, it is highly desirable that the crane 100 does not provide propulsion to the vessel. Lifting operations may be from the vessel to which the crane 100 is attached to another vessel, a dock, an offshore platform or other location. During such lifting operations, the vessel is maintained in a stationary position such that safe and accurate lifting can be performed. It will therefore be understood that it may be highly advantageous that the crane is provided such that when the crane is moved from the sailing position to the operational position, the crane’s ability to generate useful propulsion is removed. On the other hand, when the crane is moved from the operational position to the sailing position, the crane’s ability to generate useful propulsion is reinstated.

[0077] Still referring to Figure 9, the boom comprises an aperture 320 such that the mast 200 is received within the aperture 320 when the crane 100 is in the sailing position.

[0078] When in the operational position shown in Figure 9, the first wing portion and second wing portion are not individually of sufficient aerodynamic form to usefully generate propulsion. As described above, such propulsion to the vessel is not desirable during use of the crane 100 for a lifting operation.

[0079] Once the lifting operation(s) have been performed, it may again be desirable to move the vessel. In which case, the crane 100 can be returned to the sailing position such that, with sufficient natural wind, the crane 100 may provide propulsion to the vessel.

[0080] For the sake of completeness: Figures 10 and 11 show detailed views of the rear of the crane 100 and Figures 12 and 13 show cross-sectional views through the crane 100.

[0081] Figure 14 shows a detailed view of the mast 200 and pedestal I foundation block 400, where it can be seen that, in the presently described example, the boom 300 is pivotally releasably mounted to the foundation block 400. This may provide the option that the boom 300 can be easily entirely removed from the foundation block 400 and an alternatively shaped boom (not shown) attached to the foundation block 400, thus adjusting the aerodynamic profile of the complete wing when the crane 100 is in the sailing position. It may be desirable to change the aerodynamic profile of the crane 100 such that the performance of the crane 100 in propelling the vessel may be improved in forecast wind conditions, for example. In alternative examples not shown in the Figures, the attachment of the boom 300 may be by means of the described pivotally releasable mounting to the mast 200 rather than to the foundation block 400.

[0082] Figures 15 and 16 show detailed views of the hoisting winch 710 and lifting cable 500 arrangement.

[0083] Figure 17 shows a plan view of the crane 100 in the sailing position. The previously discussed chord line 800 has been marked in Figure 17, along with a plane of symmetry 810 bisecting the chord line 800. It can clearly be seen in Figure 17 that the complete wing is symmetrical about the plane of symmetry 810 bisecting the chord line 800. Such symmetry allows the complete wing to generate lift in the direction L when exposed to an airflow from either side of the complete wing. That is to say, when the complete wing is exposed to a sufficient wind from direction A, lift is generated and when the complete wing is exposed to a sufficient wind from direction B, lift is generated. The term sufficient wind should be easily understood by a person skilled in the art. Such a skilled person will understand that at very low wind speeds, negligible lift will be generated.

[0084] Still referring to Figure 17, when the complete wing is exposed to a sufficient wind from direction C, the lift generated can be optimised by rotating the complete wing, i.e. rotating the crane 100 (clockwise when viewed in plan as in Figure 17). Rotation of the crane 100 can be performed by rotation on the pedestal I foundation block 400 which can rotate / slew in a swivel on the deck of the vessel (not shown) as previously described.

[0085] Similarly, when the complete wing is exposed to a sufficient wind from direction D, the lift generated can be optimised by rotating the complete wing, i.e. rotating the crane 100 (anti-clockwise when viewed in plan as in Figure 17). Rotation of the crane 100 can be performed by rotation on the pedestal I foundation block 400 which can rotate / slew in a swivel on the deck of the vessel (not shown) as previously described.

[0086] It should be noted that alternative methods for rotation of the crane 100 (both clockwise and anti-clockwise) may be implemented in alternative examples not described herein.

[0087] It will be understood that the optimal angle of attack will heavily depend on the specific wing profile design, therefore in some complete wing profiles the optimal angle of attack may not be directions A and B as indicated in Figure 17. Furthermore, it may be satisfactory to maintain the crane 100 receiving wind from a non-optimal angle of attack, such as for example directions C or D, since a non-optimal, however still positive, lift may be provided from such angles of attack.

[0088] In some examples the crane 100 may be arranged with a suitably configured control system such that the crane 100 can be rotated into an optimal angle of attack relative to the wind direction as the wind direction and / or vessel direction changes. In alternative examples, the crane 100 may be set at a particular angle for a duration of time. Further discussion regarding the angle of attack of the wing is provided later.

[0089] It should also be noted that in some examples it may be desirable to not rotate the crane 100 to optimise the lift generated when the crane 100 is in the sailing position.

[0090] An example of an alternative complete wing is shown in Figure 17a which is a simplified schematic plan view drawing. The exemplary complete wing is shown without the other components of the crane for illustration purposes only. The complete wing is formed of a mast comprising a first wing portion (not visible in the schematic plan view shown in Figure 17a) and boom 300A comprising a second wing portion. It will easily be understood that the mast comprising the first wing portion is arranged with the boom 300A comprising the second wing portion to form a complete wing when in the sailing position shown in Figure 17a.

[0091] The exemplary complete wing of Figure 17a comprises a profile which is symmetrical about the chord line 800A. One example of a suitable wing profile may be a wing shaped according to National Advisory Committee for Aeronautics (NACA) profile number 0015. It will be appreciated that other profiles utilising symmetry about the chord line 800A may also be utilised in alternative examples not shown herein. In some examples, wing profiles without any symmetry may be used.

[0092] For completeness, a bottom view of the crane 100 in the sailing position is shown in Figure 18.

[0093] Although not shown in the Figures, the boom 300 of the presently described exemplary crane 100 is configured to be moveable to a horizontal position in use. As can be seen in Figure 4, where the boom 300 has almost reached the horizontal position, movement to the horizontal position greatly reduces the height of the crane 100 which may be highly desirable in some situations such as when the vessel to which the crane is mounted is passing under bridges, for example.

[0094] Where the boom 300 is moveable to a horizontal position in use, the vessel to which the boom 300 is mounted may be provided with a boom rest (not shown) located on the deck of the vessel and arranged to support the boom 300 when in the horizontal position.

[0095] The crane 100 performing as a complete wing in the sailing position may generate around 25,000 Newtons of forward thrust in a wind speed of around 10m / s and around 156,000 Newtons of forward thrust in a wind speed of around 25m / s. It may be estimated that such supplementary propulsion may lead to a significant reduction of fuel consumption of the vessel. It will be appreciated that the performance of the complete wing will vary drastically depending on the particular design of the complete wing, and the stated performance is given as an example only.

[0096] Figures 19 to 28 show schematic drawings of a second example of a crane 100’ for mounting on a vessel (not shown) to provide lifting operations on the vessel and propulsion to the vessel. It will be understood that by providing propulsion to the vessel, it is meant that useful propulsion is provided, i.e. propulsion which has an effect on the overall power requirements for movement of the vessel. The skilled person will be aware that such vessels that are capable of hosting cranes, such as the crane 100’ shown in Figures 19 to 28, are generally large and require a substantial amount of energy for manoeuvring and travel. The useful propulsion provided need not entirely be the primary propulsion means of the vessel, however it will be understood that useful propulsion would at least supplement the propulsion provided by the primary propulsion means to a non-negligible extent. Many of the components of the crane 100’ are similar to the first example crane 100 shown in Figures 1 to 18, therefore like reference numerals are used to indicate like parts, with the addition of prime (‘) in the second example crane 100’.

[0097] In this regard, the crane 100’ comprises major components of a mast 200’ and a boom 300’. The crane 100’ is moveable in use between a sailing position (shown in Figures 19 to 21) and an operational position (shown in Figure 22).

[0098] Although not shown in the Figures, the crane 100’ is for mounting on a sea going vessel. The crane 100’ is rotatably attached to the vessel by means of a pedestal I foundation block 400’ which can rotate / slew in a swivel on the deck of the vessel.

[0099] The crane 100’ further comprises a hoisting winch 710’ (not visible in Figures 19 to 21 , visible in Figure 22) located on the boom 300’ for reeling in and out a lifting cable 500’ used to perform hoisting operations.

[0100] The mast 200’ is arranged in a vertically upstanding configuration in the sailing position and the operational position. For the avoidance of doubt, the mast 200’ is also vertically upstanding when moving between the sailing and operational positions. A luff cable 600’ connects the mast 200 to the boom 300 and is reeled in and out by a luff cable winch 700’ to allow the boom 300’ to be lifted and lowered in use.

[0101] When in an operational position shown in Figure 22, the crane 100’ is ready to perform a hoisting operation by attaching a component to be lifted to the lifting cable 500’ and reeling it in using the hoisting winch 710’. It will be understood that myriad possible lifting operations may be performed. In some lifting operations, the crane 100’ may rotate on the swivel on the deck of the vessel. In this operational position, useful propulsion is not provided by the crane 100.

[0102] In the presently described example, the boom 300’ is pivotally releasably mounted to the foundation block 400’. This may provide the option that the boom 300’ can be easily entirely removed from the foundation block 400’ and an alternatively shaped boom (not shown) attached to the foundation block 400’, thus adjusting the aerodynamic profile of the complete wing when the crane 100’ is in the sailing position. It may be desirable to change the aerodynamic profile of the crane 100’ such that the performance of the crane 100’ in propelling the vessel may be improved in forecast wind conditions, for example. In alternative examples not shown in the Figures, the attachment of the boom 300’ may be by means of the described pivotally releasable mounting to the mast 200’ rather than to the foundation block 400’.

[0103] It will be appreciated that the particular type of crane 100’ shown in the Figures is merely an example of a possible crane with which the presently described invention finds particular utility. The presently described invention may however be used with myriad crane types, as will become apparent in due course.

[0104] Referring again to Figure 19, the crane 100’ is shown in the sailing position from a front side of the crane 100’. On the front side of the crane 100’ a convex surface is provided by the boom 300’ which optimises the aerodynamic performance of the crane 100’ when in the sailing position.

[0105] Figures 20 and 21 shows a detailed view of the crane 100’ in the sailing position from a rear side of the crane 100’. On the rear side of the crane 100’, the mast 200’ and boom 300’ together form a concave surface. In the presently described preferred example, the mast 200’ and boom 300’ together form a flush and continuous surface. As will be understood in due course, the flush and continuous concave surface formed by the mast 200’ and boom 300’ optimises the aerodynamic performance of the crane 100’ when in the sailing position shown in Figures 20 and 21. In this sailing position, useful propulsion may be generated by the crane 100’. It will be understood that as the crane is moved from the operational position to the sailing position, the crane’s ability to generate useful propulsion is reinstated. On the other hand, when the crane is moved from the sailing position to the operational position, the crane’s ability to generate useful propulsion is removed.

[0106] As will now be apparent, the mast 200’ comprises a first wing portion and boom 300’ comprises a second wing portion. When the mast 200’ and boom 300’ are arranged together in the sailing position, the mast 200’ and boom 300’ form a complete wing. When the complete wing is formed, useful propulsion can be provided by the complete wing to the vessel. In the presently described examples the complete wing comprises an under-camber profile. It will be understood that in other examples other wing profiles may be used.

[0107] Unlike the crane 100 of the first example shown in Figures 1 to 18, the boom 300’ of the crane 100’ does not comprise a cover under which the hoisting winch 710’ and lifting cable 500’ are housed. Instead, in this second exemplary crane 100’, the mast 200’ and boom 300’ are of similar height such that the mast 200’ covers the hoisting winch 710’ and lifting cable 500’ when in the sailing position. Said another way, when in the sailing position as shown in detailed view in Figure 20, the hoisting winch 710’ and lifting cable 500’ do not disturb the aerodynamic performance of the crane 100’ since the mast 200’ covers these components in this position.

[0108] In the present context, the gas stream (i.e. wind / air) is provided across the crane 100’ when the crane 100’ is in the sailing position such that the complete wing, formed by first wing portion and second wing portion, receives an air stream such that lift is generated across the complete wing. As explained above, since the complete wing is arranged in a vertically upstanding manner on the vessel, lift generated then acts as a propulsion force for the vessel.

[0109] As will be explained in more detail later, in the presently described example, the wind direction may be from either side of the wing when in use. That is to say, when the crane 100’ is arranged on a vessel such that the front side of the crane 100’ (shown in Figure 19) faces towards the forward side of the vessel and the crane 100’ is in the sailing position, the crane 100’ may be exposed to wind from the starboard or port side of the vessel and the crane 100’ may generate lift forwards. This may allow the crane 100’ to provide propulsion to the vessel when wind is provided from either the starboard side or the port side of the vessel.

[0110] As can be seen most clearly in Figure 20, in the presently described preferred example, the complete wing is symmetrical about a plane of symmetry bisecting a chord line 800’ of the complete wing. In the presently described example, the complete wing is symmetrical, however it will be understood that in alternative examples (not shown) the complete wing may be substantially symmetrical in profile such that the complete wing can generate lift when exposed to an airflow from either side of the complete wing.

[0111] It may be advantageous to provide a complete wing which can generate lift when exposed to an airflow from either side, as this may allow the crane 100’ to provide propulsion to the vessel when wind is provided from either the starboard or port side of the vessel.

[0112] Although not shown in the Figures, the complete wing may comprise an adjustable flap, or a plurality of adjustable flaps, configured to be adjusted to change the profile of the complete wing to adjust the lift generated. In some examples, the adjustable flap, or plurality of adjustable flaps, may be configured to adjust the profile of the complete wing while maintaining the complete wing substantially symmetrical about a plane of symmetry bisecting the chord line 800’. For example, the adjustable flap, or plurality of adjustable flaps, may be used to increase of decrease the camber of the complete wing, when adjustment is desirable. When such adjustment may be desirable is not described in detail here in the interest of brevity, as it will be apparent to a person skilled in the art.

[0113] Still referring to Figure 20, it can be seen that the mast 200 comprises side support members 210’, 21 T extending outwardly from the bottom of the mast 200’. The side support members 210’, 21 T extend out of a side of the bottom of the mast 200’ opposite the boom 300’. The crane 100’ further comprises a mast support cable 900’ connecting the top of the mast 200’ to the side support members 210’, 21 T and the bottom of the pedestal I foundation block 400’.

[0114] The described arrangement of the lifting cable 500’, luff cable 600’, mast support cable 900’ and side support members 210’, 21 T form a particularly advantageous arrangement. That is, the described arrangement provides compressive forces through the crane 100’ rather than bending or torsional forces. It will be apparent to a person skilled in the art that bending or torsional forces may not be entirely eliminated but that the described arrangement may provide reduced bending and / or torsional forces.

[0115] It is highly desirable to reduce bending and / or torsional forces on crane components. Compressive forces through the crane 100’ structure are easier to manage than bending and / or torsional forces. Therefore, it is desirable to reduce bending and / or torsional forces even if this results in an increase in compressive forces.

[0116] Still referring to Figure 22, the crane 100’ is shown ready to perform a hoisting operation by attaching a component to be lifted to the lifting cable 500’ and reeling it in using the hoisting winch 710’. It will be understood that myriad possible lifting operations may be performed. Although not visually shown in the Figures, the reader is reminded that in the operational position the crane 100’ may rotate on the swivel on the deck of the vessel. It will be easily understood that the luff cable 600’ in conjunction with the luff cable winch 700’ can be used to luff the boom 300’.

[0117] As can clearly be seen in Figure 22, when the crane 100’ is in the operational position shown, the first wing portion (formed of the mast 200’) and the second wing portion (formed of the boom 300’) are not together and therefore do not form a complete wing. When the crane is in the operational position, the crane’s ability to generate useful propulsion is removed.

[0118] When performing lifting operations in the operational position shown in Figure 22, it is highly desirable that the crane 100’ does not provide propulsion to the vessel. Lifting operations may be from the vessel to which the crane 100’ is attached to another vessel, a dock, an offshore platform or other location. During such lifting operations, the vessel is maintained in a stationary position such that safe and accurate lifting can be performed. It will therefore be understood that it may be highly advantageous that the crane is provided such that when the crane is moved from the sailing position to the operational position, the crane’s ability to generate useful propulsion is removed. On the other hand, when the crane is moved from the operational position to the sailing position, the crane’s ability to generate useful propulsion is reinstated.

[0119] Unlike the boom 300 of the first exemplary crane 100, the boom 300’ does not comprise an aperture for the mast 200’ to be received into when the crane 100’ is in the sailing position.

[0120] When in the operational position shown in Figure 22, the first wing portion and second wing portion are not individually of sufficient aerodynamic form to usefully generate propulsion. As described above, such propulsion to the vessel is not desirable during use of the crane 100’ for a lifting operation.

[0121] Once the lifting operation(s) have been performed, it may again be desirable to move the vessel. In which case, the crane 100’ can be returned to the sailing position such that, with sufficient natural wind, the crane 100’ may provide propulsion to the vessel. For the sake of completeness, Figures 23 and 24 show detailed views of the rear of the crane 100’ and Figures 25 and 26 show cross-sectional views through the crane 100’.

[0122] Figure 27 shows a plan view of the crane 100’ in the sailing position. The previously discussed chord line 800’ has been marked in Figure 27, along with a plane of symmetry 810’ bisecting the chord line 800’. It can clearly be seen in Figure 27 that the complete wing is symmetrical about the plane of symmetry 810’ bisecting the chord line 800’. Such symmetry allows the complete wing to generate lift in the direction L when exposed to an airflow from either side of the complete wing. That is to say, when the complete wing is exposed to a sufficient wind from direction A, lift is generated and when the complete wing is exposed to a sufficient wind from direction B, lift is generated. The term sufficient wind should be easily understood by a person skilled in the art. Such a skilled person will understand that at very low wind speeds, negligible lift will be generated.

[0123] Still referring to Figure 27, when the complete wing is exposed to a sufficient wind from direction C, the lift generated can be optimised by rotating the complete wing, i.e. rotating the crane 100’ (clockwise when viewed in plan as in Figure 27). Rotation of the crane 100’ can be performed by rotation on the pedestal I foundation block 400’ which can rotate / slew in a swivel on the deck of the vessel (not shown) as previously described.

[0124] Similarly, when the complete wing is exposed to a sufficient wind from direction D, the lift generated can be optimised by rotating the complete wing, i.e. rotating the crane 100’ (anti-clockwise when viewed in plan as in Figure 27). Rotation of the crane 100’ can be performed by rotation on the pedestal I foundation block 400’ which can rotate / slew in a swivel on the deck of the vessel (not shown) as previously described.

[0125] It should be noted that alternative methods for rotation of the crane 100’ (both clockwise and anti-clockwise) may be implemented in alternative examples not described herein.

[0126] It will be understood that the optimal angle of attack will heavily depend on the specific wing profile design, therefore in some complete wing profiles the optimal angle of attack may not be directions A and B as indicated in Figure 27. Furthermore, it may be satisfactory to maintain the crane 100 receiving wind from a non-optimal angle of attack, such as for example directions C or D, since a non-optimal, however still positive, lift may be provided from such angles of attack. In some examples the crane 100’ may be arranged with a suitably configured control system such that the crane 100’ can be rotated into an optimal angle of attack relative to the wind direction as the wind direction and / or vessel direction changes. In alternative examples, the crane 100’ may be set at a particular angle for a duration of time. Further discussion regarding the angle of attack of the wing is provided later.

[0127] It should also be noted that in some examples it may be desirable to not rotate the crane 100’ to optimise the lift generated when the crane 100’ is in the sailing position.

[0128] An example of an alternative complete wing is shown in Figure 27a which is a simplified schematic plan view drawing. The exemplary complete wing is shown without the other components of the crane for illustration purposes only. The complete wing is formed of a mast comprising a first wing portion (not visible in the schematic plan view shown in Figure 27a) and boom 300B comprising a second wing portion. It will easily be understood that the mast comprising the first wing portion is arranged with the boom 300B comprising the second wing portion to form a complete wing when in the sailing position shown in Figure 27a.

[0129] The exemplary complete wing of Figure 27a comprises a profile which is symmetrical about the chord line 800B. One example of a suitable wing profile may be a wing shaped according to National Advisory Committee for Aeronautics (NACA) profile number 0015. It will be appreciated that other profiles utilising symmetry about the chord line 800B may also be utilised in alternative examples not shown herein. In some examples, wing profiles without any symmetry may be used.

[0130] For completeness, a bottom view of the crane 100’ in the sailing position is shown in Figure 28.

[0131] The crane 100’ performing as a complete wing in the sailing position may generate around 10,000 Newtons of forward thrust in a wind speed of around 10m / s. It may be estimated that such supplementary propulsion may lead to a reduction of fuel consumption in some vessels by around 2-3%. It will be understood that in other vessels the reduction in fuel consumption may be greater or smaller.

[0132] It will be appreciated that the performance of the complete wing will vary drastically depending on the particular design of the complete wing, and the stated performance is given as an example only.

[0133] Referring to either of the exemplary cranes 100, 100’ described herein, where the term propulsion is referred to, the term is used to mean either sole propulsion means or supplementary propulsion means. Furthermore, although not described in detail, the cranes 100, 100’ described herein may be used together with other supplementary propulsion means on a vessel, such as, but not limited to, other cranes 100, 100’. In this connection, a vessel may be provided with multiple cranes 100, 100’ to provide sole or supplementary propulsion.

[0134] Figures 29 shows a propulsion force plot which is now used to provide further details of the desired angle of attack with respect to wind direction and corresponding propulsion generated for the crane 100 described with reference to Figures 1 to 17. As will be explained in more detail, in the plot shown the crane 100 is rotated such that the complete wing is optimally presented to the changing wind direction around the 360 degrees of possible wind directions.

[0135] On top of the plot of Figure 29, vessels 1 are shown with the crane 100 positioned in four different positions in Figures 29a, 29b, 29c and 29d. It will be understood that the “crane 100” is referred to herein for brevity however the skilled person will understand that, for the purposes of the discussion of Figures 29a, 29b, 29c and 29d, it is the angle of attack of the complete wing which is being discussed.

[0136] In Figure 29, the angle with respect to the fore of the vessel is provided around the outer ring of the plot while the propulsion force generated is indicated by the concentric circles.

[0137] Firstly, referring to Figure 29a, the vessel 1 is travelling in the direction of 0 degrees at around 5m / s. The vessel 1 is travelling directly into a headwind of around 10m / s in Figure 29a. That is to say, the wind direction is from 0 degrees / towards 180 degrees. It can be seen that the crane 100 has been positioned with the chord of the complete wing parallel to the wind direction because the vessel 1 is travelling directly into the wind and therefore the forwards propulsion generated (indicated by line 2) by the complete wing is zero or near zero however the drag produced by the complete wing can be reduced by aligning the chord with the wind direction as shown.

[0138] Referring to Figure 29b, the vessel 1 is travelling in the direction of 0 degrees at around 5m / s. The vessel 1 is travelling with a tailwind of around 10m / s in Figure 29b. That is to say, the wind direction is from 180 degrees / towards 0 degrees. It can be seen from the crane 100 has been positioned with the chord of the complete wing at 90 degrees to the wind direction with the rear side of the complete wing facing the wind. The vessel is travelling with the wind and therefore the propulsion generated (indicated by line 2) by the complete wing is around 5000 Newtons, however some drag is also produced.

[0139] Referring to Figure 29c, the vessel 1 is travelling in the direction of 0 degrees at around 5m / s. The wind is of around 10m / s in Figure 29c and is coming from 270 degrees I towards 90 degrees. It can be seen that the crane 100 has been positioned to optimally generate maximum propulsion for the vessel 1. As can be seen on the plot, the propulsion generated is around 23,000 Newtons.

[0140] Referring to Figure 29d, the vessel 1 is travelling in the direction of 0 degrees at around 5m / s. The wind is of around 10m / s in Figure 29d and is coming from 90 degrees

[0141] I towards 270 degrees. It can be seen that the crane 100 has been positioned to optimally generate maximum propulsion for the vessel 1. As can be seen on the plot, the propulsion generated is around 23,000 Newtons.

[0142] Referring to Figure 29, it can be seen that the complete wing is effective at generating propulsion at wind angles from around 30 degrees to 330 degrees. The complete wing may be effective at generating propulsion without rotation of the crane 100 such that the angle of attack of the complete wing is optimised with respect to the wind angle. In the preferred examples, the crane 100 can provide such rotation such that the propulsion generated can be optimised.

Claims

CLAIMS1. A crane (100, 100’) for mounting on a vessel to provide lifting operations on the vessel and propulsion to the vessel, comprising: a mast (200, 200’) comprising a first wing portion; and a boom (300, 300’) comprising a second wing portion; wherein the crane (100, 100’) is moveable between a sailing position and an operational position; wherein in the sailing position the mast (200, 200’) and boom (300, 300’) are substantially vertical and together the first wing portion and second wing portion form a complete wing; and in the operational position the mast (200, 200’) is substantially vertical and the boom (300, 300’) is tilted relative to the mast (200, 200’) such that the boom (300, 300’) can be used to lift an object; such that in use in the sailing position the crane (100, 100’) can provide propulsion to the vessel to which the crane (100, 100’) is mounted and in the operational position the crane (100, 100’) can lift or lower an object.

2. The crane (100, 100’) according to claim 1 , wherein the complete wing comprises an under camber wing profile.

3. The crane (100, 100’) according to claim 1 or 2, wherein the complete wing is substantially symmetrical in profile about a plane of symmetry (810, 810’) bisecting a chord line (800, 800’) of the complete wing.

4. The crane (100, 100’) according to any preceding claim, further comprising: at least one luffing cable (600, 600’) connecting the mast (200, 200’) to the boom (300, 300’) and configured to raise and lower the boom (300, 300’) in operation; and at least one lifting cable (500, 500’) connected to the boom (300, 300’) and configured to raise and lower an object in operation.

5. The crane (100, 100’) according to claim 4, further comprising: at least a first winch (700, 700’) configured to reel in and out the luffing cable (600, 600’); andat least a second winch (710, 710’) configured to reel in and out the lifting cable (500, 500’).

6. The crane (100, 100’) according to any preceding claim, wherein in the sailing position the mast (200, 200’) and boom (300, 300’) are releasably attached together.

7. The crane (100, 100’) according to any preceding claim, wherein in the sailing position the first wing portion and second wing portion together form a continuous surface.

8. The crane (100, 100’) according to any preceding claim, wherein the boom (300, 300’) comprises a recess or aperture (320) such that the mast (200, 200’) is received within the recess or aperture (320) when the crane (100, 100’) is in the sailing position.

9. The crane (100, 100’) according to any preceding claim, wherein the mast (200, 200’) is connected to a foundation block (400, 400’) configured to rotate in a swivel on the deck of a vessel in use.

10. The crane (100, 100’) according to claim 9, wherein the mast (200, 200’) and foundation block (400, 400’) are integrally formed.

11. The crane (100, 100’) according to any preceding claim, wherein the boom (300, 300’) is configured to be moveable to a substantially horizontal position in use.

12. The crane (100, 100’) according to any preceding claim, wherein the boom (300, 300’) is pivotally releasably mounted to the mast (200, 200’) or the foundation block (400, 400’).

13. The crane (100, 100’) according to any preceding claim, wherein the boom (300, 300’) portion further comprises an adjustable flap configured to adjust the camber of the wing in use to optimise the propulsion provided.

14. A system configured to provide lifting operations and propulsion on a vessel, the system comprising: a vessel; and a crane (100, 100’) according to any of claims 1 to 13 rotatably mounted on the vessel.

15. A method of optimising the propulsion provided to a vessel, comprising the steps of: providing a system according to claim 14; moving the crane (100, 100’) to the sailing position; and locating the system in a wind stream such that the crane (100, 100’) provides propulsion to the vessel.

16. Use of a system according to claim 14 to provide propulsion to the vessel.

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