Sailing crane system

Abstract

A sailing crane system 1 comprises a column 10 comprising a base 20 and a body 30, a sail boom 50 coupled to the base and a load-bearing boom (70, Fig 7), extending between a proximal end (71, Fig 7)

Description

The present invention relates to a sailing crane system, a kit of parts comprising the sailing crane system and a method of operating the sailing crane system. Background Using wind to power cargo ships is the future of global shipping to ensure reduction in emissions and improve sustainability of maritime trade and commerce. Many such cargo ships employ cranes for lifting and manoeuvring loads. CN204548462 describes a marine crane where one boom is employed that is swung to vertical when used as a mast for sailing and is swung to horizontal when used as a crane. However, such an arrangement does not provide for aerodynamic sailing. It has been considered to employ separate sailing masts and booms compared to cranes. However, as discussed in JP58156490, inclusion of sail masts in a ship that already includes cranes can result in interference and reduced effectiveness of the cranes and of the sails. JP58156490 describes an arrangement where separate sailing and crane masts are employed, and the crane mast can rotate about the sailing mast. Movement of the crane mast can be controlled separately from the sailing mast. The sailing mast can be fixed relative to the deck of the boat during use of the crane and during use of the sailing mast, the crane can be fixed in place. However, in such an arrangement, the sailing configuration is still not aerodynamically favourable. Therefore, there exists a need to provide a sailing crane system that not only avoids interference between the sail boom and crane boom but more efficiently harnesses the wind power without compromising the effectiveness of the crane functionality. Summary The claimed invention provides a sailing crane system comprising: a column comprising a base and a body; a sail boom coupled to the base; a load-bearing boom extending between a proximal end and a distal end, wherein the proximal end of the load-bearing boom is rotatably coupled to the body, the load-bearing boom being configured to rotate between: (i) a stowed boom configuration in which a longitudinal axis (L) of the load-bearing boom is aligned with a longitudinal axis (X) of the column; and (ii) a load-bearing configuration. The sailing crane system of the claimed invention can be arranged in an efficient and aerodynamic sailing configuration with the column, and optionally also the load-bearing boom, functioning as a mast. The mast formed in the sailing configuration may be referred to herein as a sailing mast. The sailing configuration enabling the wind power to effectively harnessed. The sailing crane system can also be arranged in a load-bearing configuration with the column and load-bearing boom functioning as a crane. Providing both a sail boom and a load-bearing boom where the sail boom is coupled to a part of the column that is below the load-bearing boom, the sail boom does not interfere with operation of the load-bearing boom when the system is used as a crane. By providing a load-bearing boom that is configured to rotate between a stowed boom configuration where the load-bearing boom is aligned with the longitudinal axis of the column and a load-bearing configuration, the load-bearing boom does not negatively impact the aerodynamics of the sailing configuration or interfere with the sail(s) when in the stowed-configuration and the system is used for sailing. The column may have a longitudinal axis along which the base and the body are coaxially aligned when the column is configured for sailing i.e. in a sailing configuration. The body and base may each a respective longitudinal axis. Coaxial used herein meaning that the longitudinal axes are aligned such that they are on a common axis. The body may be arranged above the base. Herein, spatially relative terms, such as “under”, "below", "beneath", "lower", “over”, "above", "upper" and the like, may be used herein to describe one element or feature's relationship to another elements) orfeature(s) during normal use of the sailing crane system. Herein, direct coupling between features referring to coupling between features with no intervening component. Herein the term “length” refers to a dimension in a longitudinal direction, a longitudinal direction being a direction aligned with the longitudinal axis. The load-bearing boom extends between a proximal end and a distal end along its longitudinal axis. When the load-bearing boom is in the stowed configuration, the longitudinal axis of the load-bearing boom is aligned with the longitudinal axis of the column. In the stowed configuration, the longitudinal axis of the load-bearing boom may be coaxial with (i.e. on a common axis) or parallel to (aligned with but laterally spaced apart from) the longitudinal axis of the column. The body may be rotatably coupled to the base. The body and / or base may be rotatable relative to each other about the longitudinal axis of the column. Rotation of the body about the longitudinal axis of the column in turn rotates the load-bearing boom coupled thereto, which facilitates its function to manoeuvre as a crane arm / boom. The base may comprise a sail boom coupling section and a sail coupling section, wherein the sail boom coupling section is coupled to the sail boom, wherein the sail coupling section is couple to receive a luff edge of a sail portion in use. Optionally, the sail boom coupling section is rotatably coupled to the sail coupling section such that the sail coupling section is rotatable relative to the sail boom coupling section about the longitudinal axis of the column. The sail coupling section may be arranged above the sail boom coupling section. The base may be rotatably coupled to a support configured to fix to a deck of a sailing vessel in use. The sailing crane system may comprise engagement means configured to releasably lock the sail boom coupling section to the support to prevent relative rotation therebetween. The sail coupling section may comprise a first base groove configured to receive a luff edge of a first sail portion in use. The luff edge may optionally be provided with one or more guide elements, such as sail slides or sail slugs. The body may comprise a first body groove configured to receive the luff edge of the first sail portion in use. The first base groove and the first body groove may be configured to directly receive the luff edge of the first sail portion. Alternatively, the luff edge may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first base groove and first body groove may be configured to directly receive the guide element(s) of the luff edge of the first sail portion. The body may be rotatable about a longitudinal axis of the column relative to the sail coupling section to a sailing position in which the first base groove is aligned with the first body groove. The sail coupling section may also be rotatable about the longitudinal axis of the column relative to the body. In the sailing position, the sail coupling section and the body may be locked together with the first base groove aligned with the first body groove. The sail coupling section may comprise a second base groove configured to receive a luff edge of a second sail portion in use. In particular, the sail coupling section of the base may comprise the second base groove. The body may comprise a second body groove configured to receive the luff edge of the second sail portion in use. The second base groove and the second body groove may be configured to directly receive the luff edge of the first sail portion. Alternatively, the luff edge may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the second base groove and second body groove may be configured to directly receive the guide element(s) of the luff edge of the second sail portion. The body may be rotatable about the longitudinal axis of the column relative to the base to the sailing position in which the second base groove is aligned with the second body groove such that the sailing crane system is configured for use with a wing sail. In the sailing position, the sail coupling section and the body may be locked together with the second base groove aligned with the second body groove. The sailing crane system of the claimed invention is particularly advantageous when first and second base grooves and first and second body grooves are employed such that the system is configured for use with a wing sail. Wing sails employ two sail portions, referred to herein as first and second sail portions, that are typically substantially identical, each having a luff edge and a leech edge. The luff edge at the foot (i.e. at the bottom of the sail portion) being coupled to the column and the leech edge being coupled to an end of the sail boom that is distal from the column. The first and second base grooves are configured to have a luff edge of a sail portion coupled thereto. When the first base groove is aligned with the first body groove, the first base groove and first body groove together form a continuous groove that is configured to receive the luff edge of a sail portion. The first base groove and the first body groove may be configured to directly receive the luff edge of the first sail portion. Alternatively, the luff edge may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first base groove and first body groove may be configured to directly receive the guide elements) of the luff edge of the first sail portion. In use, hoisting a first sail portion may involve sliding the luff edge (or the guide element(s) of the luff edge) of the first sail portion along the continuous groove formed by the first base groove and first body groove such that the luff edge extends along the sail coupling section of the base and the body of the column. Similarly, when the second base groove is aligned with the first body groove, the second base groove and second body groove together form a continuous groove that is configured to receive the luff edge of a sail portion. Consequently, in use, hoisting a second sail portion may involve sliding the luff edge of the sail portion (or the guide element(s) of the luff edge) along the continuous groove formed by the second base groove and second body groove such that the luff edge extends along the sail coupling section of the base and the body of the column. According to such a system, a wing sail may be employed when the system is in the sailing configuration, since the first and second body grooves and first and second base grooves enable coupling of first and second sail portions to the column functioning as a sailing mast where the loadbearing boom is arranged in its stowed configuration with its longitudinal axis is aligned with the longitudinal axis of the column functioning as a sailing mast thereby not impacting the aerodynamics of the wing sail or interfering with the sail portions when hoisted. The first body groove and the second body groove may be spaced apart along a surface of the body. The first base groove and the second base groove may be similarly spaced apart along a surface of the sail coupling section. Accordingly, in use with a wing sail, the sail portions are spaced apart according to the grooves. The body may comprise a trailing surface where the first body groove is formed along a first edge of the trailing surface and the second body groove is formed along a second edge of the trailing surface. Similarly, at least the sail coupling section of the base may comprise a trailing surface where the first base groove is formed along a first edge of the trailing surface and the second base groove is formed along a second edge of the trailing surface. The trailing surface may be planar / flat. Optionally, a leading surface of the body and / or base may be curved. In such an arrangement, the resulting column may be D-shaped, which is particularly advantageous for achieving aerodynamics when employing a wingsail. In the art, such a trailing surface may be referred to as a trailing edge of a mast. As used herein, the term “leading” and “trailing” refers to the orientation of the mast formed by the sailing crane system when in the sailing configuration The terms “leading” and “trailing” are well known terms of art in the context of a sailing mast. Herein, the leading surface of a component being the a surface forming the leading edge / surface of the mast when the sailing crane system is in the sailing configuration. The trailing surface of a component being a surface forming the trailing edge / surface of the mast when the sailing crane system is in the sailing configuration. The trailing edge / surface of the mast formed by the sailing crane system in the sailing configuration having the sailing boom attached thereto. The leading edge / surface of the mast formed by the sailing crane system in the sailing configuration being opposite the trailing edge / surface. The first body groove and / or the second body groove may extend along more than 70% of the length of the body, preferably more than the 90% of the length of the body, more preferably the entire length of the body. The first base groove and / or the second base groove may extend along more than 70% of the length of the sail coupling section of the base, preferably more than the 90% of the sail coupling section of the base, more preferably the entire length of the sail coupling section of the base. The load-bearing boom may be referred to herein as a derrick boom or a knuckle boom depending on its configuration. The load-bearing boom may be a derrick boom that is configured such that, in the stowed configuration, a distal end of the boom is positioned adjacent to or received within the column. When the system is in the sailing configuration with the derrick boom in the stowed configuration, the derrick boom does not interfere with the sail boom or sails. A proximal end of the derrick boom may be rotatably coupled to a part of the body between the first body groove and the second body groove. In one example, a proximal end of the derrick boom may be rotatably coupled to the trailing surface of the body between the first body groove and the second body groove. This is particularly advantageous, since, when used with a wing sail, the derrick boom would be stowed between the two sail portions during sailing thereby minimising the impact of the derrick boom on the aerodynamics of the wing sail. The body may comprise an elongate recess configured to receive a portion of the derrick boom in use when in the stowed configuration. The elongate recess may be formed in a first surface of the body. The derrick boom and recess may be configured such that, in use with the derrick boom in the stowed configuration, the derrick boom is received within the recess such that the derrick boom is flush with the first surface of the body. This is particularly advantageous for minimising the impact of the derrick boom on the aerodynamics of the wing sail. The first surface may be the leading or the trailing surface of the body. In particular, the first surface may be the trailing surface. Therefore, derrick boom may be received within the recess such that the derrick boom is flush with the trailing surface of the body. The column may further comprise an upper portion rotatably coupled to an upper end of the body at an upper joint about which the upper portion is rotatable such that the upper portion may be angularly displaced relative to the longitudinal axis X of the column. The upper joint may arranged at an opposite side of the column from where the load-bearing boom is attached. When the sailing crane system is in a sailing configuration, the upper portion may be arranged above the body such that it is coaxial with the body to maximise the height of the column thereby enhancing the function of the column as a mast. The upper portion may be arranged adjacent to the body when the sailing crane system is in a load-bearing configuration thereby reducing the height of the column and improving stability when the sailing crane system is used as a crane. The upper portion may comprise a first upper groove configured to receive a luff edge of a first sail portion in use, wherein the upper groove is aligned with the first body groove when a longitudinal axis of the upper portion is coaxial with the longitudinal axis X of the column. The upper portion may comprise a second upper groove configured to receive a luff edge of a second sail portion in use. The first upper groove and the second upper groove may be configured to directly receive the luff edge of the first sail portion and second sail portion, respectively. Alternatively, the luff edge of each of the first and second sail portions may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first and second upper grooves may be configured to directly receive the guide element(s) of the luff edge of the first and second sail portions, respectively. The second upper groove may be aligned with the second body groove when a longitudinal axis of the upper portion is coaxial with the longitudinal axis X of the column. When the first base groove is aligned with the first body groove and when the first upper groove is aligned with the first body groove (i.e. with the upper portion coaxial with the longitudinal axis of the column and the body and base in the sailing position), the first base groove, the first body groove and the first upper groove together form a continuous groove that is couple to receive the luff edge of a first sail portion. Consequently, in use, hoisting a first sail portion may involve sliding the luff edge of the sail portion (or guide element(s) of the luff edge) along the continuous groove formed by the first base groove, first body groove and first knuckle boom groove such that the luff edge extends along the base and body of the column and the knuckle boom. Similarly, when the second base groove is aligned with the second body groove and when the second upper groove is aligned with the second body groove (i.e. with the upper portion coaxial with the longitudinal axis of the column and the body in the sailing position), the second base groove, the second body groove and the second upper groove together form a continuous groove that is configured to receive the luff edge of a second sail portion. Consequently, in use, hoisting a second sail portion may involve sliding the luff edge (or guide element(s) of the luff edge) of the second sail portion along the continuous groove formed by the second base groove, second body groove and second upper groove such that the luff edge extends along the base, body and upper portion of the column. The first upper groove and / or the second upper groove may extend along more than 70% of the length of the upper portion, preferably more than the 90% of the length of the upper portion, more preferably the entire length of the upper portion. The load-bearing boom may be referred to as a knuckle boom if rotatably coupled to an upper end of the body. The knuckle boom may be configured to rotate between a stowed boom configuration in which it is arranged above the body and coaxial with the longitudinal axis of the column and with the longitudinal axis of the body; and a load-bearing configuration. In the load-bearing configuration, the knuckle boom may be angularly displaced from the longitudinal axis of the body. When the sailing crane system is in the sailing configuration, the knuckle boom and the column together function as a sailing mast. The knuckle boom may comprise one or more portions that are rotatably coupled together at knuckle boom joints such that each portion can be angularly displaced relative to the longitudinal axis of an adjacent portion. The longitudinal axis of the knuckle boom may be the axis along the length of the knuckle boom when the portions of the knuckle boom are coaxial. The knuckle boom may comprise a proximal portion comprising the proximal end of the knuckle boom and a distal portion comprising the distal end of the knuckle boom, wherein, in the stowed boom configuration, a longitudinal axis of the proximal portion, a longitudinal axis of the distal portion and the longitudinal axis of the column are coaxial. In an arrangement employing a proximal portion and a distal portion, the longitudinal axis of the knuckle boom may be the axis along the length of the knuckle boom when the proximal and distal portions of the knuckle boom are coaxial with each other. The proximal portion and the distal portion may be rotatably coupled together at a knuckle boom joint such that the distal portion can be angularly displaced relative to a longitudinal axis of the proximal portion. The knuckle boom may further comprise one or more intermediate portion(s) rotatably coupled between the proximal portion and the distal portion. Each intermediate portion(s) may be coupled to an adjacent portion of the knuckle boom (which may be a further intermediate portion, the proximal portion or the distal portion) via a knuckle boom joint such that each intermediate portion can be angularly displaced relative to a longitudinal axis of the adjacent portion. The knuckle boom may comprise a first knuckle boom groove configured to receive a luff edge of a first sail portion in use with the knuckle boom in the stowed boom configuration, wherein the first body groove is aligned with the first knuckle boom groove when the knuckle boom is in the stowed boom configuration. The knuckle boom may comprise a second knuckle boom groove configured to receive a luff edge of a second sail portion in use with the knuckle boom in the stowed boom configuration, wherein the second body groove is aligned with the second knuckle boom groove when the knuckle boom is in the stowed boom configuration. The first knuckle boom groove and the second knuckle boom groove may be configured to directly receive the luff edge of the first sail portion and second sail portion, respectively. Alternatively, the luff edge of each of the first and second sail portions may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first and second knuckle boom grooves may be configured to directly receive the guide element(s) of the luff edge of the first and second sail portions, respectively. When the first base groove is aligned with the first body groove and when the first knuckle boom groove is aligned with the first body groove (i.e. with the knuckle boom in the stowed configuration and the body in the sailing position), the first base groove, the first body groove and the first knuckle boom groove together form a continuous groove that is configured to receive the luff edge of a first sail portion. Consequently, in use, hoisting a first sail portion may involve sliding the luff edge of the first sail portion (or guide element(s) of the luff edge) along the continuous groove formed by the first base groove, first body groove and first knuckle boom groove such that the luff edge extends along the sail coupling section of the base of the column, the body of the column and the knuckle boom. Similarly, when the second base groove is aligned with the second body groove and when the second knuckle boom groove is aligned with the second body groove (i.e. with the knuckle boom in the stowed configuration and the body in the sailing position), the second base groove, the second body groove and the second knuckle boom groove together form a continuous groove that is couple to receive the luff edge of a second sail portion. Consequently, in use, hoisting a second sail portion may involve sliding the luff edge of the second sail portion (or guide elements) of the luff edge of the second sail portion) along the continuous groove formed by the second base groove, second body groove and second knuckle boom groove such that the luff edge extends along the sail coupling section of the base of the column, the body of the column and the knuckle boom. As discussed above, the body may comprise a trailing surface that may be planar. The knuckle boom may comprise a knuckle boom trailing surface that is coplanar with the trailing surface of the body when the knuckle boom is in the stowed configuration. The first knuckle boom groove and / or the second knuckle boom groove may extend along more than 70% of the length of the knuckle boom, preferably more than the 90% of the length of the knuckle boom, more preferably the entire length of the knuckle boom. The knuckle boom may be formed of the portion(s) described above (proximal portion, distal portion and / or intermediate portion(s)). The load-bearing boom (which may be the derrick boom or the knuckle boom) may comprise one or more pulleys and / or comprises a hook configured to lift a load proximal to the distal end of the loadbearing boom. When the load-bearing boom is a knuckle boom having proximal and distal portions coupled together at a knuckle joint, as discussed above, a first hook configured to lift a first load may be employed proximal to its distal end and / or a second hook configured to lift a second load may be employed proximal to the knuckle joint. The sailing crane system may further comprise a controller and one or more motor(s) configured to control angular displacement of the load-bearing boom from the stowed configuration. The controller and one or more motor(s) may control the angular displacement of the load-bearing boom independently of relative rotation of the body and base. The sailing crane system may further comprise a wing sail, wherein the wing sail comprises a first sail portion comprising a luff edge and a leech edge and a second sail portion comprising a luff edge and a leech edge, wherein the luff edges of the first and second sail portions are coupled to the of the column. By way of example, in use, with the sailing crane system in a sailing configuration, the sail portions are coupled to the base and the body of the column when the sail portions are hoisted. When the sail portions are stowed away, the sail portions may be coupled to the base and may be, for example, folded or furled. In such an arrangement, the sail portions are optionally flexible sail portions. The sailing crane system may further comprise a boom vang coupled between the sail boom and the sail coupling section and configured to adjust the angle between the longitudinal axis of the base and the sail boom. Optionally, the boom vang may be configured as a linear actuator extending between the sail boom and the sail boom coupling section. In accordance with the claimed invention, there is also provided a kit of parts comprising: the sailing crane system described above; and a wing sail comprising a first sail portion and a second sail portion. In accordance with the claimed invention, there is also provided a sailing vessel comprising the sailing crane system described above, wherein the base is rotatably coupled to a deck of the sailing vessel. In accordance with the claimed invention, there is also provided a method of operating the sailing crane system described above, the method comprising: rotating the load-bearing boom from the stowed boom configuration to the load-bearing configuration; and / or rotating the load-bearing boom from the load-bearing configuration to the stowed boom configuration. Rotating the load-bearing boom from the stowed boom configuration to the load-bearing configuration may be performed to change the sailing crane system from being in a sailing configuration to being in a load-bearing configuration. Rotating the load-bearing boom from the load-bearing configuration to the stowed boom configuration may be performed to change the sailing crane system from being in a load-bearing configuration to being in a sailing configuration. The method may further comprise rotating the body relative to the sail coupling section of the base about the longitudinal axis of the column. Rotating the body relative to the sail coupling section of the base may be performed while the sailing crane system is in the load-bearing configuration to enable the load-bearing boom to be rotated relative to the longitudinal axis of the column for manoeuvring loads. Rotating the body relative to the sail coupling section of the base may be performed when moving the sailing crane system from a load-bearing configuration to a sailing configuration to align the grooves of the base and body such that they form a continuous groove thereby enabling a sail portion to be moved along the continuous groove to hoist the sail portion such that its luff edge extends along the base and body. The teaching above in respect of the sailing crane system described above equally applies to the method. Brief Description of Figures Figure 1 is a schematic diagram of an exemplary sailing crane system according to a first embodiment of the claimed invention with the sailing crane system in a sailing configuration, the sailing crane system comprising a wingsail having first and second sail portions that are hoisted. Figure 2 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a sailing configuration with the first and second sail portions furled. Figure 3 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a sailing configuration with the first and second sail portions furled. Figure 4 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a sailing configuration with the first and second sail portions furled. Figure 5 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a load-bearing configuration with the first and second sail portions furled. Figure 6 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a load-bearing configuration with the first and second sail portions folded. Figure 7 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system in a load-bearing configuration with the sail portions folded, the sailing crane system employing pulleys and a hook. Figure 8 is a schematic diagram of the exemplary sailing crane system of Figure 1 with the sailing crane system arranged at an intermediatory configuration between the sailing configuration and the load-bearing configuration. Figure 9 is a schematic diagram of a plan view of a longitudinal section of the exemplary sailing crane system of Figure 1 arranged at an intermediatory configuration between the sailing configuration and the load-bearing configuration. Figure 10 is a schematic diagram of a plan view of a longitudinal section of the exemplary sailing crane system of Figure 1 arranged at an intermediatory configuration between the sailing configuration and the load-bearing configuration. Figure 11 is a schematic diagram of an exemplary sailing crane system according to a second embodiment of the claimed invention with the sailing crane system in a sailing configuration, the sailing crane system comprising sail portions that are hoisted. Figure 12 is a schematic diagram of the exemplary sailing crane system of Figure 11 in the sailing configuration where the first and second sail portions are not shown. Figure 13 is a schematic diagram of the exemplary sailing crane system of Figure 11 in the sailing configuration where the first and second sail portions are not shown. Figure 14 is a schematic diagram of a perspective view of a longitudinal section of the exemplary sailing crane system of Figure 11 in the sailing configuration where the first and second sail portions are not shown. Figure 15 is a schematic diagram of the exemplary sailing crane system of Figure 11 in the sailing configuration with the first and second sail portions are furled. Figure 16 is a schematic diagram of the exemplary sailing crane system of Figure 11 in the loadbearing configuration with the first and second sail portions furled. Figure 17 is a schematic diagram of the exemplary sailing crane system of Figure 11 in the loadbearing configuration where the first and second sail portions are not shown. Figure 18 is a schematic diagram of a perspective view of a longitudinal section of the exemplary sailing crane system of Figure 11 in the load-bearing configuration where the first and second sail portions are not shown. Figure 19 is a plan view of a longitudinal section of part of the column and load-bearing boom of the exemplary sailing crane system of Figure 11 in the load-bearing configuration. Figure 20 is a schematic diagram of part of the column and load-bearing boom of the exemplary sailing crane system of Figure 11 in the load-bearing configuration. Figure 21 is a perspective view of a longitudinal section of part of the column, support and sail boom of the sailing crane system according to the first and second embodiments. Detailed Description Figures 1 to 10 are schematic diagrams an exemplary sailing crane system 1 according to a first embodiment of the claimed invention. The sailing crane system 1 having a column 10, a load-bearing boom 70 and a sail boom 50. The sailing crane system 1, and column 10 of the sailing crane system 1, being arranged in either a sailing configuration or a load-bearing configuration. The sailing crane system 1 can be readily reconfigured between the sailing configuration and the load-bearing configuration. The sailing configuration provides an aerodynamic mast and sail configuration for highly efficient sailing. The load-bearing configuration provides an effective crane configuration. Herein, spatially relative terms, such as “under”, "below", "beneath", "lower", “over”, "above", "upper" and the like, may be used herein to describe one element or feature's relationship to another element(s) orfeature(s) during normal use of the sailing crane system 1. The column 10 has a longitudinal axis X. The longitudinal axis X being defined by the central axis extending longitudinally through the column 10 when the column 10 (and the system 1) is in the sailing configuration. The sailing configuration is shown in, for example, Figures 1 to 4. The column 10 comprises a base 20 and a body 30. In normal use, the body 30 of the column 10 is coupled to and arranged above the base 20 of the column 10. The body 30 may extend between a lower end 31 and an upper end 32 defining a longitudinal axis Y of the body therebetween. The longitudinal axis Y of the body 30, at least with the column 10 in the sailing configuration, is co-axial with the longitudinal axis X of the column 10. Co-axial used herein meaning that the longitudinal axes are aligned such that they are on a common axis. Le., in this case, the body extends longitudinally along, and is centred with the longitudinal axis X of the column 10. The body 30 may optionally taper towards its upper end 32. The base 20 may extend between a lower end 21 and an upper end 22 and has a longitudinal axis Z defined therebetween. The longitudinal axis Z of the base, at least with the column 10 in the sailing configuration, is coaxial with the longitudinal axis X of the column 10 i.e. the base is centred with the longitudinal axis X of the column 10. Therefore, the longitudinal axis Z of the base 20 and the longitudinal axis Y of the body 30 are both coaxial with the longitudinal axis X of the column 10. Optionally, the longitudinal axis Z of the base 20 and the longitudinal axis Y of the body 30 are both coaxial with the longitudinal axis X of the column 10 when the column 10 is in the sailing configuration and when the column 10 is in the load-bearing configuration, as shown in Figures 1 to 10. As shown in Figures 1 to 10, the base 20 may comprise a sail boom coupling section 23 and a sail coupling section 24. The sail boom coupling section 23 may be arranged below the sail coupling section 24 such that the sail boom coupling section 23 comprises the lower end 21 of the base 20 and the sail coupling section 24 comprises the upper end 22 of the base 20. The sail boom coupling section 23 may be rotatably coupled to the sail coupling section 24 such that the sail coupling section 24 is rotatable relative to the sail boom coupling section 23 about the longitudinal axis X of the column 10. The sail boom coupling section 23 and the sail coupling section 24 of the base 20 are described in further detail below. The sailing crane system 1 may comprise a support 90, as shown in Figures 1 to 10. The sail boom coupling section 23 may be rotatably coupled to the support 90 that is fixed to a deck of a vessel in normal use, as described in further detail below. The support 90 being fixed to the deck of a vessel means that the support 90 cannot move relative to the deck of a vessel. The reference to each “end” of the base or body 20, 30 herein may be an end face or an open end of the relevant portion 20, 30. The base or body 20, 30 or the sail boom coupling section 23 or sail coupling section 24 of the base 20 may be hollow, e.g. they may be in the form of an outer shell or housing defining an inner void. The body 30 and the sail coupling section 24 of the column 10 when in the sailing configuration optionally form a curved front surface 10c, referred to as a leading surface or leading edge in the art. The body 30 and the sail coupling section 23 of the column 10 when in the sailing configuration also optionally form a substantially flat / planar rear surface 10d, referred to as a trailing surface or trailing edge in the art. Such a configuration for the column in the sailing configuration is often referred to as having a D-shaped cross section or being a D-shaped mast. The curved front surface 10c is particularly advantageous for improving aerodynamics during sailing. The term “leading” and “trailing” refers to the orientation of the mast formed by the sailing crane system when in the sailing configuration. The terms “leading” and “trailing” are well known terms of art in the context of a sailing mast. Herein, the leading surface of a component being a surface forming the leading edge / surface of the mast when the sailing crane system is in the sailing configuration. The trailing surface of a component being a surface forming the trailing edge / surface of the mast when the sailing crane system is in the sailing configuration. The trailing edge / surface of the mast formed by the sailing crane system in the sailing configuration having the sailing boom attached thereto. The leading edge / surface of the mast formed by the sailing crane system in the sailing configuration being opposite the trailing edge / surface. Each of the body 30 and the sail coupling section 24 of the base 20 may have a respective leading surface 30c, 20c that is optionally curved, particularly convex. The sail coupling section 24 may have a respective trailing surface 20d that is optionally flat / planar. The body 30 may have a trailing surface 30d that is optionally flat / planar except for a recess 33 formed therein. In use, to move from the load-bearing configuration to the sailing configuration, the body 30 may be rotated relative to the sail coupling section 24 of the base 20 about the longitudinal axis X of the column 10 to align the body 30 with the sail coupling section 24 such that their trailing surfaces 20d, 30d are coplanar and their leading surfaces 20c, 20d form a continuous leading surface, which in this example is convex. This aligned position may be referred to herein as the sailing position. The body 30 and the base 20 are coupled together. The body 30 and the base 20 are optionally rotatably coupled together such that the body 30 can rotate about the longitudinal axis X of the column 10 relative to at least part of the base 20. As discussed above, the base 20 may comprise a sail boom coupling section 23 and a sail coupling section 24. The body 30 may be rotatably coupled to the sail coupling section 24 that comprises the upper end 22 of the base 20 such that the body 30 can rotate about the longitudinal axis X of the column 10 relative to the sail coupling section 24 of the base 20. The body 30 may rotate about the longitudinal axis of the column 10 relative to the sail coupling section 24 of the base 20 while the longitudinal axis Z of the base 20 and the longitudinal axis Y of the body 30 remain co-axial with the longitudinal axis X of the column 10, as shown by comparing, for example, Figures 1 to 4 to Figures 5 to 10. The sail coupling section 24 may also be rotatable about the longitudinal axis X of the column 10 relative to the body 30. When the column 10 is in the sailing configuration, the sail coupling section 24 of the base 20 and the body 30 may be releasably locked together by, for example, complementary engagement features (not shown). The complementary engagement features being configured to releasably lock the body 30 to the sail coupling section 24 of the base 20 such that there is no relative rotation between the body 30 and the sail coupling section 24. The complementary engagement features may comprise one or more pins and corresponding openings. The locking features may be hydraulically or electrically actuated. The sail coupling section 24 and the body 30 may be coupled together by an alignment shaft 100, as best shown in Figure 21, which is a rigid shaft extending longitudinally through at least the upper part of the sail coupling section 24 and at least the lower end 21 of the body 20. The alignment shaft is optionally hollow for minimising its weight. The sail boom coupling section 23 and the sail coupling section 24 may also be coupled together by the alignment shaft 100. Optionally, as best shown in Figure 21, one alignment shaft 100 may extend longitudinally through the sail coupling section 24, the sail boom coupling section 23 and the body 30 to couple the sail coupling section 24, the sail boom coupling section 23 and the body 30 together. The alignment shaft 100 is optionally coaxial with the longitudinal axis X of the column 10. As discussed above, the base and body 20, 30 are typically hollow thereby enabling the alignment shaft to extend therethrough. As best shown in Figure 21, the base and body 20, 30 optionally surround and encase the alignment shaft 100 extending therethrough. The diameter of the alignment shaft(s) 100 may be sized such that there is a clearance fit between the alignment shaft 100 and each of the sail coupling section 24, sail boom coupling section 23 and the body 30. In the optional arrangement of the first embodiment shown in Figures 1 to 10, as exemplified by Figure 21, the sail coupling section 24 and the sail boom coupling section 23 may be able to rotate relative to, and about the alignment shaft 100. The body 30 may be fixed relative to the alignment shaft 10 by one or more fixing means such that the body 30 does not rotate relative to the alignment shaft 10. The alignment shaft 100 may optionally extend co-axial to the longitudinal axis X of the column 10 thereby maintaining alignment of the sail coupling section 24, the sail boom coupling section 23 and the body 30 with the longitudinal axis X of the column 10. As discussed above, when the column 10 is in the sailing configuration, the sail coupling section 24 of the base 20 and the body 30 may be releasably locked together by, for example, complementary engagement features (not shown) such that there is no relative rotation between the body 30 and the sail coupling section 24. If the alignment shaft 100 is employed and the body 30 is fixed to the alignment shaft 100 such that the body 30 does not rotate relative to the alignment shaft 100, then the complementary engagement features may be employed between the sail coupling section 24 and the alignment shaft 100 or directly between the sail coupling section 24 and the body 30. As best shown in Figure 21, a lower end 100a of the alignment shaft 100 may be coupled to the support 90 fixed to a deck of a vessel (not shown) in normal use. The lower end 100a of the alignment shaft 100 being proximal to the sail boom coupling section 23. The lower end 100a of the alignment shaft 100 may optionally be received within a corresponding socket 91 in the support 90 or deck of the sailing vessel. There may be a clearance fit between the corresponding socket 91 and the lower end 100a of the alignment shaft 100 such that the alignment shaft 100 can rotate relative to the support 90. In the example shown in Figure 21, the support 90 extends circumferentially around the longitudinal axis X of the column 10 and the socket 91 is centred with the longitudinal axis X of the column 10. The socket 91 being configured to receive the lower end 100a of the alignment shaft 100. The socket 91 may comprise projecting portions 92, 93 configured to at least partially surround the lower end 100a of the alignment shaft 100. The lower end 100a of the alignment shaft 100 may be of reduced diameter compared to the remainder of the alignment shaft 100. The projecting portions 92, 93 of the socket 91 may be interposed between the lower end 100a of the alignment shaft 100 and the sail boom coupling section 23. This is best shown in Figure 21. As discussed above, the base 20, in particular the sail boom coupling section 23 of the base 20 may be coupled to the support 90 fixed to a deck of a vessel in normal use. In particular, the sail boom coupling section 23 of the base 20 may be rotatably coupled to the support 90. As best shown in Figure 21, a support gear mechanism 110 may be employed to drive and control rotation of the sail boom coupling section 23 relative to the support 90. The support gear mechanism 110 may comprise a first gear 111 and a second gear 112. The second gear 112 being fixed to, optionally integrally formed with, the sail boom coupling section 23 such that the second gear 112 does not rotate relative to sail boom coupling section 23. The first gear 111 being rotatably mounted to the support 90, for example via a pin extending through the centre of the second gear 112 into a corresponding opening in the support 90. The second gear 112 is optionally formed as a skirt circumferentially surrounding the sail boom coupling section 23 and having teeth arranged circumferentially therearound. The teeth of the first gear 111 being configured to mesh with the teeth of the second gear 112 such that the first gear 111 can function as a driver gear and cause rotation of the second gear 112 (the driven or follower gear). Rotation of the first gear 111 therefore causes rotation of the sail boom coupling section 23 relative to the support 90. The operation of the support gear mechanism 110 may be, for example hydraulically or electrically actuated. The support gear mechanism 110 may be controlled to lock the first gear 111 so that is does not rotate and so prevent rotation of the sail boom coupling section 23 relative to the support 90 when the sailing crane system 1 is in the load-bearing configuration. This is advantageous for restricting rotation of the sail boom 50 coupled to the sail boom coupling section 23 relative to the vessel during load-bearing and so preventing interference between the sail boom 50 and the loadbearing boom 70. When in the sailing configuration, the first gear 111 can be controllably rotated to, in turn, controllably rotate of the sail boom coupling section 23, and so sail boom 50 coupled thereto, relative to the support 90 (and relative to the vessel that the support 90 is fixed to). This may be advantageous for efficient sailing. The rotation of the alignment shaft 100, and so body 30 optionally fixed thereto, about the longitudinal axis X of the column 10, relative to the sail boom coupling section 23 may be driven by one or more gear mechanisms. For example, as best shown in Figure 21, the rotation of the alignment shaft 100 relative to the sail boom coupling section 23 may be driven by a shaft gear mechanism 120. The operation of the shaft gear mechanism 120 may be, for example hydraulically or electrically actuated. The shaft gear mechanism 120 may comprise a primary gear 121 and a secondary gear 122. The secondary gear 122 being fixed to, optionally integrally formed with, the alignment shaft 100 such that the secondary gear 122 does not rotate relative to the alignment shaft 100. The primary gear 121 being rotatably coupled to the sail boom coupling section 23. Optionally, the primary gear 121 is received within a corresponding slot 23a in the sail coupling section 23. The primary gear 121 may be rotatably coupled to the sail boom coupling section 23, for example by a pin extending through the centre of the primary gear 121 that engages with the periphery of the corresponding slot 23a. The primary gear 121 having teeth configured to mesh with teeth of the secondary gear 122. The teeth of the secondary gear 122 optionally being arranged circumferentially around an outer periphery of the alignment shaft 100. The secondary gear 122 may be fixed to or integrally formed with the alignment shaft 100. The primary gear 121 can function as a driver gear and cause rotation of the secondary gear 122 (the driven or follower gear). The shaft gear mechanism 120 may therefore be controlled to drive rotation of the alignment shaft 100, and so the body 30 that may be fixed thereto, relative to the sail boom coupling section 23. Control of the rotation of the primary gear 121 therefore enables control of positioning of the load-bearing boom 70 that is coupled to the body 30 when the system 1 is in the load-bearing configuration. The shaft gear mechanism 120 may also be used to control rotation of the alignment shaft 100 about the longitudinal axis X, and so body 30 optionally fixed thereto, to align the first body groove 30a and first base groove 20a and to align the second body groove 30b and the second base groove 20b when transitioning to the sailing configuration. When performing such an alignment, the support gear mechanism 110 may be controlled to restrict rotation of the sail boom coupling section 23 relative to the support 90 and so restrict rotation of the sail boom 50. As the sail coupling section 24 is coupled to the sail boom 50 via the first and second sail portions 61,62, this in turn provides some restriction of rotation of the sail coupling section 24. It may also be desirable to further restrict rotation of the sail coupling section 24 by releasably lock the sail coupling section 24 to the sail boom 50 and / or the sail boom coupling section 23 during such alignment. Restricting rotation of the sail coupling section 24 about the longitudinal axis X may be helpful while the body 30 is rotated about the longitudinal axis X to align the first body and base grooves 20a, 20b and to align the second body and base grooves 20b, 30b. The shaft gear mechanism 120 may be controlled to lock the primary gear 121 so that is does not rotate and so prevent rotation of the alignment shaft 100, and so body 30 optionally fixed thereto, about the longitudinal axis X. This may be advantageous when the sailing crane system 1 is not in operation either as a crane or a sail. The sailing crane system 1 comprises a sail boom 50 coupled to the base 20 of the column 10. In particular, the sail boom 50 may be directly coupled to the base 20 of the column 10. The sail boom 50 is rotatably coupled to the base 20. More specifically, the sail boom 50 may be rotatably coupled to the sail boom coupling section 23 of the base 20. The sail boom 50 may longitudinally extend between a proximal end 51 and a distal end 52. The proximal end 51 of the sail boom 50 may be rotatably coupled to the sail boom coupling section 23 of the base 20. The sail boom 50 may extend transverse to, optionally substantially orthogonal to, a trailing surface 23d of the sail coupling section 23. The trailing surface 23d of the sail coupling section 23 being the surface of the sail coupling section 23 proximal to the stern (rear) of the vessel during normal use with the sailing crane system 1 in the sailing configuration. Typically, as is known in the art, a gooseneck may be used to couple such a sail boom to a mast and may similarly be employed herein to couple the sail boom 50 to the sail boom coupling section 23 of the base 20. The gooseneck (not shown) may comprise a projecting portion / pin extending from the sail boom coupling section 23 of the base 20 that is received within a corresponding socket in the sail boom 50 thereby coupling the sail boom 50 to the sail boom coupling section 23 of the base 20. The sail boom 50 may be rotatably coupled to the sail boom coupling section 23 of the base 20 such that an angle between the longitudinal axis Z of the base 20 and the sail boom 50 may be within a range of, for example, 70-110 degrees. The sail boom may be pivotally coupled to the sail boom coupling section 23 such that it remains in the same vertical plane as the sail coupling section 23. . A boom vang 54 may also be used, optionally in addition to the gooseneck 53, to couple the sail boom 50 to the sail coupling section 23 of the base 20, as best shown in Figure 21. The boom vang 54 being used to adjust the angle between the longitudinal axis Z of the base 20 and the sail boom 50. Boom vangs are known in the art for this purpose but typically are provided in the form of pulleys and cables. However, the boom vang 54 employed in the sailing crane system 1 is optionally provided in the form of a linear actuator extending between the sail boom and the sail boom coupling section 23. Retraction or extension of the linear actuator forming the boom vang 54 causes angular displacement of the sail boom 50 relative to the longitudinal axis Z of the base 20. The boom vang 54 may be coupled to a part of the sail boom 50 that is near to the proximal end 50a of the sail boom 50. The boom vang 54 may be coupled to a part of the sail coupling section 23 below the gooseneck. The sailing crane system 1 comprises a load-bearing boom 70 extending between a proximal end 71 and a distal end 72. A longitudinal axis L of the load-bearing boom 70 being defined between the proximal end 71 and the distal end 72 of the load-bearing boom 70. The proximal end 71 of the loadbearing boom 70 is rotatably coupled to the body 30. Optionally, the load-bearing boom 70 is directly coupled to the body 30, The load-bearing boom 70 is configured to rotate between: (i) a stowed boom configuration in which the load-bearing boom 70 is aligned with the longitudinal axis X of the column 10; and (ii) a load bearing configuration. In the first embodiment, the distal end 72 of the load-bearing boom 70 is positioned adjacent to or received within the body 30 of the column 10. This type of load-bearing boom is referred to herein as a derrick boom and labelled with reference numeral 70 herein. “Derrick” is employed only as a labelling term used to distinguish this type of load-bearing boom from the “knuckle” boom 70’ described in the second embodiment. The proximal end 71 of the derrick boom 70 may be coupled to a part of the body 30 proximal to the lower end 31 of the body 30. In the first embodiment, the longitudinal axis L of the load-bearing boom 70 when in the stowed configuration may be parallel to, but spaced apart from, the longitudinal axis X of the column (and the longitudinal axis Y of the body 30) when stowed, as shown in Figure 3. When in the stowed configuration, the longitudinal axis L of the load-bearing boom 70 may be coaxial with the longitudinal axis X of the column (and the longitudinal axis Y of the body 30). The load-bearing boom 70 when configured as a derrick boom may be of solid construction in contrast to the sail boom 50 and the body and bases 20, 30 of the column 10 that are hollow. In the stowed boom configuration shown in Figures 1 to 4, the longitudinal axis L of the derrick boom 70 is optionally generally / substantially parallel to the longitudinal axis X of the column 10 (and the longitudinal axis Y of the body 30). By parallel to, it is meant that the longitudinal axis L of the derrick boom 70 is aligned with but laterally spaced apart from the longitudinal axis X of the column 10. The derrick boom 70 is in the stowed configuration when the sailing crane system 1 (and so the column 10 of the sailing crane system 1) is in the sailing configuration. The proximal end 71 of the derrick boom 70 is rotatably coupled to the body 30. More specifically, the proximal end 71 of the derrick boom 70 may be pivotably coupled to the body 30 by a pivot joint, for example a hinge, that enables the load-bearing boom 70 to pivot away from the longitudinal axis X of the column (and away from the longitudinal axis Y of the body 30). The pivot joint may be formed between the trailing surface 30d of the body 30 and the proximal end 71 of the derrick boom. The derrick boom 70 may be pivotably coupled to the body 30 by a pivot joint (not shown) that enables the load-bearing boom 70 to pivot away from the longitudinal axis X of the column 10 by up to, for example, 90-120 degrees, preferably 90-110 degrees when in the load-bearing configuration. In the load-bearing configuration, the load-bearing boom may be pivoted away from the longitudinal axis X of the column 10 while remaining in the same vertical plane as the body 30, as shown in Figure 6. For stability, as shown in Figure 1, the derrick boom 70 may taper towards its distal end 72, as shown in Figures 5 and 6. As best shown in Figures 5 and 6, in the first embodiment, the body 30 optionally has an elongate recess 33 configured to receive a portion of the derrick boom 70 in use when in the stowed configuration. Receiving the derrick boom 70 in the recess when in the stowed configuration if advantageous for avoiding interference between the derrick boom 70 and sail portions during sailing. The elongate recess 33 is optionally formed in the trailing surface 30d of the body 30. The trailing surface 30d of the body 30 being the surface of the body 30 proximal to the stern (rear) of the vessel during normal use with the sailing crane system 1 in the sailing configuration. Depending on the depth of the elongate recess 33 (and thickness of the derrick boom 70), the longitudinal axis of the derrick boom 70 may be coaxial with or parallel to the longitudinal axis X of the column 10 (and the longitudinal axis Y of the body 30) when in the stowed configuration. In the optional configuration of the first embodiment, as best shown in Figure 3, in the stowed configuration, the elongate recess 33 receives a portion of the derrick boom 70 such that the derrick boom 70 is flush with the trailing surface 30d of the body 30 and parallel to the longitudinal axis Y of the body 30 (and parallel to the longitudinal axis X of the column 10). The derrick boom 70 may be locked in the elongate recess 33 when in the stowed configuration, for example, by complementary engagement means on the derrick boom 70 and body 30 or by the derrick boom 70 and elongate recess 33 being dimensioned such that the derrick boom 70 is press-fit into the elongate recess 33. In the optional configuration shown in Figure 3, the derrick boom 70 may have an outer major surface 76 and an inner major surface 77 and a thickness defined therebetween. The inner major surface 77 and outer major surface 76 extend longitudinally. The inner major surface 77 being closer to the recess 33 than the outer major surface. The outer major surface 76 is optionally substantially planar. When in the stowed configuration, the derrick boom 70 may be flush with the trailing surface 30d of the body 30 such that the outer major surface 76 and the periphery of the recess 33 are coplanar and may form a generally continuous planar surface. The inner major surface may be profiled such that the thickness of the derrick boom varies along its length. The thickness of the derrick boom 70 may taper towards its distal end and / or towards its proximal end. The derrick boom 70 may comprise a central portion having a constant thickness. As best shown in Figure 3, the derrick boom 70 may be received within the elongate recess 33 such that it is flush with the trailing surface 30d of the body 30 when the sailing crane system is in the sailing configuration. In such an embodiment, with the body 30 and the base 20 in the sailing position and the derrick boom 70 in the stowed configuration, the outer major surface 76 of the derrick boom may be flush with, and so forms part of the trailing surface of the body, which in this example is optionally planar. Therefore, the outer major surface 76 of the derrick boom 70, the trailing surface 30d of the body 30 and the trailing surface 23d of the sail coupling section 23 of the base 20 may together form a substantially continuous, trailing surface, which in this example is planar. Therefore, in the sailing configuration, the column 10 may comprise a generally continuous leading surface 110, which is optionally convex and a generally continuous trailing surface, which is optionally planar. As discussed above, once the body 30 and the sail coupling section 24 of the base 20 are aligned in the sailing position, they can be locked together to prevent relative rotation therebetween by complementary engagement means between the sail coupling section 24 and the body 30. As shown in Figure 1, the sailing crane system 1 may be configured for use with a wingsail 60. The wing sail 60 employs two sail portion, referred to herein as first and second sail portions 61,62, that may be substantially identical, each having a luff 61 a, 62a (a front edge towards the bow or front of the sailing vessel) and a leech 61 b, 62b (a trailing edge towards the stern or rear of the sailing vessel). Each of the first and second sail portions 61,62 may comprise one or more battens 63 extending from the leech end 61a, 62a to the luff end 61b, 62b that may be spaced apart along the length of the sail portion 61,62. In the depicted embodiments, the first and second sail portions 61,62 are optionally each flexible such that they can be furled, as shown in Figures 2 to 5 or folded / stacked, as shown in Figures 6 or 7 when stowed while the sailing crane system 1 (and so column 10) is in the load-bearing configuration. The combination of a column 10 that forms a D-shaped mast when in the sailing configuration and a wing sail 60 achieves an aerodynamic aerofoil. The luff edge of each sail portion 61,62 may optionally comprise one guide elements (not shown), such as sail slides or sail slugs that ease coupling of the sail portion to the column. Guide elements such as sail slides or sail slugs are well known in the art. As best shown in Figures 2 and 3, the sail coupling section 24 of the base 20 may comprise a first base groove 20a configured to receive a luff edge 61a of a first sail portion 61 in use and the body 30 may comprise a first body groove 30a configured to receive the luff edge 61a of the first sail portion 61 in use. The first base groove 20a and the first body groove 30a may be configured to directly receive the luff edge 61a of the first sail portion 61. Alternatively, the luff edge 61a of the first sail portion 61 may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first base groove and first body groove may be configured to directly receive the guide element(s) of the luff edge 61a of the first sail portion 61. As discussed above, the body 30 may be rotatable about the longitudinal axis X of the column 10 relative to the sail coupling section 24 of the base 20. In particular, the body 30 may be rotatable about the longitudinal axis X of the column 10 relative to the sail coupling section 24 of the base 20 to a position in which the first base groove 20a is aligned with the first body groove 30a. This position is referred to herein as the sailing position and the sailing position would be employed when the sailing crane system 1 (and so column 10) is in the sailing configuration. The sail coupling section 24 of the base 20 may also be rotatable about the longitudinal axis X of the column 10 relative to the body 30 so that the sailing position is reached. The sail coupling section 24 of the base 20 and the body 30 may be locked together in the sailing position i.e. with the first base groove 20a aligned with the first body groove 30a. The sail coupling section 24 of the base 20 and the body 30 may be locked together by, for example, complementary engagement features (not shown) configured to engage the sail coupling section 24 to the body 30. The complementary engagement features may comprise one or more pins and corresponding openings. The complementary engagement features may be hydraulically or electrically actuated. As discussed above, the body 30 may be fixed to the alignment shaft 100 and so the body 30 may, together with the alignment shaft 100, be rotatable about the longitudinal axis X of the column 10 relative to the sail coupling section 24. In such an arrangement, the complementary engagement features may be arranged between the sail coupling section 24 and the alignment shaft 100 or directly between the sail coupling section 24 and the body 30. The sail coupling section 24 of the base 20 may comprise a second base groove 20b configured to receive a luff edge 62a of a second sail portion 62 in use and the body 30 may comprise a second body groove 30b configured to receive the luff edge 62a of the second sail portion 62 in use. The body 30 may be rotatable about its longitudinal axis Y relative to the sail coupling section 24 of the base 20 to the sailing position in which the second base groove 20b is aligned with the second body groove 30b such that the sailing crane system 1 is configured for use with first and second sail portions 61,62 of a wing sail 60. The base 20 and the body 30 may be locked together in the sailing position i.e. with the second base groove 20b aligned with the second body groove 30b. The sail coupling section 24 of the base 20 and the body 30 may be locked together by, for example, complementary engagement features (not shown) configured to releasably lock the sail coupling section 24 and the body 30, as discussed above. The second base groove 20b and the second body groove 30b may be configured to directly receive the luff edge 62a of the second sail portion 62. Alternatively, the luff edge 62a of the second sail portion 62 may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the second base groove 20b and the second body groove 30b may be configured to directly receive the guide element(s) of the luff edge 62a of the second sail portion 62. When the first base groove 20a is aligned with the first body groove 30a (i.e. in the sailing position), the first base groove 20a and the first body groove 30a together form a substantially continuous groove that is configured to receive the luff edge 61 a of a first sail portion 61. Consequently, in use, hoisting a first sail portion 61 may involve sliding the luff edge 61a of the first sail portion 61 (or sliding one or more guide element(s) of the luff edge 61a of the first sail portion 61) along the substantially continuous groove formed by the first base groove 20a and first body groove 30a such that the luff edge 61a extends longitudinally along the sail coupling section 24 of the base 20 and the body 30 of the column 10. When the second base groove 20b is aligned with the second body groove 30b (i.e. in the sailing position), the second base groove 20b and the second body groove 30b together form a continuous groove that is configured to receive the luff edge 62a of a second sail portion 62. Consequently, in use, hoisting a second sail portion 62 may involve sliding the luff edge 62a of the second sail portion 62 (or sliding one or more guide element(s) of the luff edge 62a) along the continuous groove formed by the second base groove 20b and second body groove 30b such that the luff edge 62a extends longitudinally along the base 20 and the body 30 of the column 10. According to such a system 1, a wing sail 60 may be employed when the sailing crane system 1 is in the sailing configuration, as shown in Figure 1, since the first and second body grooves 30a, 30b and first and second base grooves 20a, 20b enable coupling of first and second sail portions 61,62 to the column 10, which functions as a sailing mast. As best shown in Figure 2, the first body groove 30a and the second body groove 30b may be spaced apart along the trailing surface 30d of the body 30. The first base groove 20a and the second base groove 20b may be similarly spaced apart along the trailing surface 20d of the base 20. Accordingly, in use with a wing sail 60, the first and second sail portions 61,62 are spaced apart according to the spacing between the first and second body / base grooves 20a,20b, 30a, 30b, as shown in Figure 1. The first and second body grooves 30a, 30b are optionally formed along opposite edges of the trailing surface 30d of the body 30 and the first and second base grooves 20a, 20b are optionally formed along opposite edges of the trailing surface 20d of the base 20. The grooves 20a, 20b, 30a, 30b are optionally formed as recesses in the outer edges of the trailing surfaces 20d, 30d. In the exemplary embodiment shown, the column optionally has a D-shaped cross section when in the sailing configuration and so its leading surface 10c is optionally curved and its trailing surface 10d is optionally planar. Consequently, the leading surfaces 20c, 30c of the sail coupling section 23 and of the body 30 are optionally curved and the trailing surfaces 20d, 30d of the sail coupling section 23 and the body 30 are optionally planar. The first and second body grooves 30a, 30b are optionally formed as recesses in the outer edges of the trailing surfaces 20d, 30d that are optionally substantially planar such that the luff edges 61 a, 62a would be substantially flush with the curved leading surfaces 20c, 30c of the base 20 and body 30 when the first and second sail portions 61,62 are hoisted. The first and second sail portions 61,62 may be arranged in a stowed configuration when the sailing crane system 1 is in the load-bearing configuration. The first sail portion 61 when in the stowed configuration may be separately furled or stowed to the second sail portion 62. At least part of the luff edges 61a, 62a may remain coupled to the sail coupling section 23 of the base 20 of the column 10 when stowed. Therefore, even when stowed, the first sail portion 61 would remain spaced apart from the second sail portion 62 according to the spacing of the grooves 20a, 20b of the body 20, as shown in Figures 3 to 7. The first sail portion 61 may be coupled at its leech end 61b to the sail boom 50, particularly near to the distal end 52 of the sail boom 50, using a first attachment and the second sail portion 62 may be coupled at its leech end 62b to the sail boom 50, particularly near to the distal end 52 of the sail boom 50 using a second attachment. The first and second sail portions 61,62 may therefore be coupled to the sail boom 50 independently. The first and second attachments may be first and second clews. The use of clews to attach sail portions to booms is well known in the art. The first and second sail portions 61,62 may therefore not be attached directly together but only via the sail boom 50. The first and second sail portions 61,62 may optionally remain attached to the sail boom 50 when stowed. In the first embodiment, the column 10 optionally employs an upper portion 40. As shown in Figures 1 and 2, the upper portion 40 of the column 10 optionally has the same cross-sectional shape as the body 30 and sail coupling section 23 such that the sail coupling section 23, body 30 and upper portion 40 together form the column 10 having a generally continuous leading surface 10c and generally continuous trailing surface 10d when the column 10 is in the sailing configuration. In the exemplary version of the first embodiment shown, the column 10 optionally has a D shaped cross section and so the upper portion 40 similarly has a D shaped cross section with a curved, convex leading surface 40c and a planar trailing surface 40d. The upper portion 40, similarly to the base 20 and body 30, is optionally formed as a hollow tubular section optionally with open lower and upper ends 41,42. The upper portion 40 is optionally rotatably coupled to the upper end 32 of the body 30 at an upper joint 43 about which the upper portion 40 is rotatable. The upper joint 43 being arranged at an opposite side of the column 10 from the load-bearing boom 70. More specifically, the upper joint 43 is arranged on an opposite side of the column 10 from the joint that rotatably couples the derrick boom 70 to the body 30. The upper joint 43 may be arranged on the leading (convex) surface of the column. The upper joint 43 may be a pivot joint such that the upper portion 40 is optionally pivotably coupled to the upper end 32 of the body 30, the upper portion 40 remaining in the same vertical plane as the body 30 while pivoting about the upper joint 43. As best shown in Figure 5, the derrick boom 70 rotates away from the longitudinal axis Y of the body 30 in an opposite direction from the upper portion 40 rotating about the upper joint 43. More specifically if the upper portion 40 and the derrick boom 70 are pivotably coupled to the body, then the upper portion 40 pivots away from the longitudinal axis Y of the body 30 in an opposite direction from the direction in which the derrick boom 70 pivots away from the longitudinal axis Y of the body 30 but the upper portion 40 and the derrick boom 70 both remain in the same vertical plane as the body 30. The upper portion 40 may extend longitudinally along its longitudinal axis U between a lower end 41 of the upper portion 40 and an upper end 42 of the upper portion 40. The upper portion 40 may taper towards its upper end 42. As shown in Figure 1, when the column 10 is in the sailing configuration the upper portion 40 has its longitudinal axis U coaxial with the longitudinal axis X and so also coaxial with the longitudinal axis Z of the base 20 and the longitudinal axis Y of the body 30. Therefore, when the column 10 is in the sailing configuration, the upper portion 40, the base 20 and the body 30 together form the longitudinally extending column 10 that functions as a sailing mast. The upper portion 40 and the body 30 may have complementary engagement means that may be configured to lock the upper portion 40 coaxial with the body 30 when the column 10 is in the sailing configuration. The upper portion 40 when coaxial with the body 30 may be referred to as being in its sailing position. When moving the column 10 from the sailing configuration to the load-bearing configuration, the upper portion 40 may be rotated about the upper joint 43 away from the longitudinal axis X of the column 10 (and so away from the longitudinal axis Y of the body 30). As shown in Figure 8, the upper portion 40 can be pivoted about the pivot joint 43 such that the upper portion 40 is folded against the body 30, which may be referred to as its folded position. In its folded position, the longitudinal axis U of the upper portion 40 is parallel to the longitudinal axis X of the column (and parallel to the longitudinal axis Y of the body 30) thereby reducing the overall height of the column 10, as shown in Figure 6. In other words, the upper portion 40 can be rotated through, specifically pivoted through, approximately 180 degrees from the principle longitudinal axis X to reach the load-bearing configuration. This is useful for stability when the sailing crane system 1 is used in the load-bearing configuration. Pivoting of the upper portion 40 about the pivot joint 43 is best shown in Figure 7, which depicts the upper portion 40 at an intermediatory position between its sailing position and its folded position. As shown in Figures 9 and 10, the sailing crane system 1 may further comprise a linkage mechanism 80 comprising a plurality of links 81,82,83 configured to pivotably couple the upper portion 40 to the body 30. The plurality of links may comprise first, second and third links 81,82, 83 where the first link 81 and the second link 82 are pivotably coupled together via the third link 83, the third link 83 being arranged between the first link 81 and the second link 82. The third link 83 may be pivotably connected to the upper pivot joint 43. Movement of the first and second links 81,82 may cause the third link 83 to pivot about the upper pivot joint 43. The first link 81 may be a first linear actuator. The second link 82 may be a second linear actuator. The third link 83, as shown in Figure 5, may be configured as one or more plate(s) which are pivotably coupled each of the first and second links 81, 82. Where the third link 83 is configured as multiple plates, those plates may be parallel. The first link and / or second link may each comprise a first link bar 81a, 82a pivotably connected between the parallel plates. As shown in Figures 9 and 10, the first link 81 may be at least partially housed within the upper portion 40 and the second link 82 may be at least partially housed within the body 30. In the sailing configuration, the first link 81 and the second link 82 may be wholly housed with the upper portion 40 and the body 30, respectively. The third link 83 may be housed partly within the body 30 and partly within the upper portion 40 when the column 10 is in the sailing configuration. Part of the third link 83 may optionally extend through one or more slots (not shown) in the housing / shell forming the body 30 and / or the upper portion 40 such that the upper joint 43 is arranged on the outer surface of the column 10. The remainder of the third link 83 not already extending through the slot(s) may be exposed when the upper portion 40 is rotated about the upper joint 43 on moving from the sailing configuration to the load-bearing configuration. The end of the first link 81 distal from the third link 83 is coupled to an inner surface of the housing / shell forming the upper portion 40 such that its position relative to the longitudinal axis of the upper portion 40 is fixed. The end of the second link 82 distal from the third link is coupled to an inner surface of the housing / shell forming the body 30 such that its position relative to the longitudinal axis of the body 30 is fixed. Movement of the first and second links 81,82 causes the third link 83 to pivot about the upper pivot joint 43 thereby pivoting the upper portion 40 between its position when the column 10 in the sailing configuration with the longitudinal axis U of the upper portion 40 being coaxial with the longitudinal axis Y of the body 30 to its position when the column 10 is in the load-bearing configuration with the longitudinal axis U of the upper portion 40 being parallel to the longitudinal axis Y of the body 30. When the first link 81 is formed as a first linear actuator and the second link 82 is formed as a second linear actuator, extension of the first actuator 81 and of the second actuator 82 causes the upper portion 40 to pivot about the upper pivot joint 43 such that the upper portion 40 pivots away from the principle longitudinal axis X such that its longitudinal axis U is at a non-zero angle to the longitudinal axis Y of the body 30. In particular, the third link 83 may pivot through 180 degrees such that the upper portion 40 is pivoted about the upper pivot joint 43 to be adjacent to the body 30 such that its longitudinal axis U is and parallel to the longitudinal axis Y of the body. The first and second linear actuators 81,82 can be controlled to control the angle at which the upper portion 40 is pivoted away from the principle longitudinal axis X relative to the body 30. Similarly, retraction of the first actuator 81 and of the second actuator 82 causes the upper portion 40 to pivot from the load-bearing configuration to the sailing configuration. As shown in Figures 1 to 5, the upper portion 40 may comprise a first upper groove 40a configured to receive the luff edge 61a of the first sail portion 61 and a second upper groove 40b configured to receive a luff edge 62a of a second sail portion 62 in use when the sailing crane system 1 is in the sailing configuration and the longitudinal axis U of the upper portion 40 is coaxial with the longitudinal axis Y of the body 30. The first upper groove 40a and the second upper groove 40b may be configured to directly receive the luff edge 61a of the first sail portion 61 and the luff edge 62a of the second sail portion 62, respectively. Alternatively, the luff edge 61a, 62a of each of the first and second sail portions 61,62 may optionally be provided with one or more guide elements, such as sail slides or sail slugs and the first and second upper grooves may be configured to directly receive the guide element(s) of the luff edge of the first and second sail portions, respectively. In the sailing configuration as shown in Figures 1 and 2, the first body groove 30a, the first upper groove 40a and the first base groove 20a may together form a continuous groove that is configured to receive the luff edge 61 a of a first sail portion 61. Consequently, in use, hoisting a first sail portion 61 may involve sliding the luff edge 61 a of the first sail portion 61 (or the guide element(s) of the luff edge 61a of the first sail portion 61) along the continuous groove formed by the first base groove 20a, first body groove 30a and the first upper groove 40a such that the luff edge 61a extends longitudinally along the base 20, the body 30 and the upper portion 40 of the column 10. Similarly, in the sailing configuration as show in Figures 1 and 2, the second base groove 20b is aligned with the second body groove 30b and the second body groove 30b is aligned with the second upper groove 40b so that the second base groove 20b, the second body groove 30b and the second upper groove may together form a substantially continuous groove that is configured to receive the luff edge 62a of the second sail portion 62. Consequently, in use, hoisting the second sail portion 62 may involve sliding the luff edge 62a of the second sail portion 62 (or the guide element(s) of the luff edge 62a of the second sail portion 62) along the substantially continuous groove formed by the second base groove 20b, the second body groove 30b and the second upper groove 40b such that the luff edge 62b extends along longitudinally along the base, body and upper portions 20, 30,40 of the column 10. As best shown in Figure 3, the first upper groove 40a and the second upper groove 40b are optionally spaced apart along the trailing surface 40d of the upper portion 40. The first and second upper grooves 40a, 40b are optionally formed along opposite edges of the trailing surface 40d of the upper portion 40. The first and second upper grooves 40a, 40b are optionally formed as recesses in the outer edges of the trailing surface 40d of the upper portion 40. In the exemplary embodiment shown, the column 10 optionally has a D-shaped cross section when in the sailing configuration and so its leading surface 10c is optionally curved and its trailing surface 10d is optionally planar. Consequently, the leading surface 40c of the upper portion 40 is optionally curved and the trailing surface 40d of the upper portion 40 is optionally planar. The first and second upper grooves 40a, 40b are optionally formed as recesses in the outer edges of the trailing surface 40d of the upper portion 40 that is optionally planar such that the luff edges 61a, 62a are substantially flush with the curved leading surface 40c of the upper portion 40 when the sail portions 61,62 are hoisted. In use, the sailing crane system 1 is arranged in the sailing configuration as shown in Figure 1 function as an aerodynamic aerofoil and can be re-arranged in the load-bearing configuration to function effectively as a load-bearing crane. To arrange the sailing crane system 1 in the sailing configuration, the sail coupling section 24 and the body 30 are arranged in the sailing position by rotating the body 30 relative to the sail coupling section 24 such that the first body groove 30a is aligned with the first base groove 20a and the second body groove 20b is aligned with the second body groove 30b. The body 30 and sail coupling section 24 are then releasably locked in this sailing position, for example by complementary engagement features (not shown), such that the body 30 can no longer rotate relative to the sail coupling section 24. Where present, the upper portion 40 is rotated about the upper joint 43 to reach its sailing position where the upper portion 40 is above the base 30 and the longitudinal axis U of the upper portion 40 is coaxial with the longitudinal axis X of the column (and so also coaxial with the longitudinal axis Y of the body 30). The upper portion 40 in its sailing position therefore increases the overall height of the column 10 thereby maximising the amount of wind power that can be harnessed when the column 10 is used as a mast during sailing. The upper portion 40 when arranged in its sailing position may be releasably locked to the body 30, for example by complementary engagement features (not shown) between the upper portion 40 and the body 30. The derrick boom 70 is rotated to its stowed configuration. Optionally in the embodiments shown, the derrick boom 70 when in its stowed configuration is flush with the trailing surface 30d of the body 30. The leading surfaces of the upper portion, the body and the sail coupling section 40c, 30c, 20c optionally together form a substantially continuous leading surface 10c ofthe column 10, which is optionally convex. The trailing surfaces of the upper portion, the body and the sail coupling section 40d, 30d, 20d (together with the outer surface 76 ofthe derrick boom 70) optionally form a substantially continuous trailing surface 10d of the column 10, which is optionally planar. Therefore, the aerodynamics ofthe column 10 are improved, which may be important for the column 10 to function as an aerodynamic mast when in the sailing configuration. Furthermore, the derrick boom 70 does not interfere with the sail portions 61,62 when in its stowed configuration. The first upper groove 40a, the first body groove 30a and the first base groove 20a together form a substantially continuous groove configured for receipt ofthe luff edge 61a ofthe first sail portion 61. The second upper groove 40b, the second body groove 30b and the second base groove 20b together form a substantially continuous groove configured for receipt of the luff edge 62a ofthe second sail portion 62. At least part ofthe luff edge 61a ofthe first sail portion 61 may already be coupled to the first groove 20a ofthe base 20 when furled or folded and at its leech edge 61 b to the sail boom 50. At least part of the luff edge 62a ofthe second sail portion 62 may already be coupled at its luff edge 62a to the second groove 20b ofthe base 20 and at its leech edge 62b to the sail boom 50. The first sail portion 61 may be hoisted from its furled or stacked position along the substantially continuous groove formed by the first base groove 20a, first body groove 30a and first upper groove 40a such that the luff edge 61a ofthe first sail portion 61 extends longitudinally along the sail coupling section 24, the body 30 and the upper portion 40 within the substantially continuous groove. Mechanisms for hoisting sails is well known in the art. The second sail portion 62 may be hoisted from its furled or stacked position along the substantially continuous groove formed by the second base groove 20b, second body groove 30b and second upper groove 40b such that the luff edge 62a ofthe second sail portion 62 extends longitudinally along the sail coupling section 24, the body 30 and the upper portion 40 within the substantially continuous groove. The first and second sail portions 61,62 therefore forming the wing sail 60, the first and second sail portions 61,62 being spaced apart according to the spacing between the first and second grooves ofthe sail coupling section 20a, 20b, between the first and second grooves ofthe body 30a, 30b and between the first and second grooves ofthe upper portion 40a, 40b. In use, in the sailing configuration, the sail coupling section 24, the body 30 and the upper portion 40 may all be fixed together such that they cannot rotate relative to each other. The sail boom coupling section 23 is rotatably coupled to the support 90. The support 90 would be fixed the deck of a vessel (not shown) such that the support 90 does not rotate relative to the deck ofthe vessel. In the sailing configuration, the sail boom coupling section 23 can rotate relative to the sail coupling section 24, that rotation being restricted by the coupling ofthe sail portions 61,62 to the sail boom at their leech edges 61 b, 62b by one or more clews. In the sailing configuration, the sail boom coupling section 23 can also rotate relative to the support 90. Therefore, the column 10 as a whole can rotate relative to the sailing vessel during sailing for enhanced aerodynamics. To change the sailing crane system 1 from the sailing configuration to the load-bearing configuration, which is shown in, for example, Figure 5, the first and second sail portions 61,62 may be lowered within the substantially continuous grooves such that they only remain coupled to the first and second base grooves 20a, 20b, respectively. The first and second sail portions 61,62 may be furled or stacked to arrive at their stowed configuration. Mechanisms for lowering and furling / stacking sails that may be employed are well known in the art. The upper portion 40, where present, may be rotated about the upper joint 43 through approximately 180 degrees to its folded position where the upper portion 40 is adjacent to the body 30 and the longitudinal axis U of the upper portion 40 is parallel to the body 30. This therefore reduces the overall height of the column 10 thereby improving stability which may be important when the column 10 is used as a crane. The derrick boom 70 is rotated away from the longitudinal axis Y of the body 30 to its load-bearing configuration. The body 30 is unlocked from the sail coupling section 24 such that it can freely rotate relative to the sail coupling section 24 about the longitudinal axis X of the column 10, for example, by releasing the complementary engagement features (not shown). The derrick boom 70 may remain in the same vertical plane as the body 30 during rotation of the body 30 about its longitudinal axis Y. The angular displacement of the derrick boom 70 from the longitudinal axis X of the column (and longitudinal axis Y of the body 30) can be varied thereby adjusting the height of the distal end 72 of the derrick boom for receiving and lifting loads. The rotation of the body 30 about the longitudinal axis X of the column 10 allows the derrick boom 70 to be rotated about the longitudinal axis X of the column 10 to manoeuvre loads being lifted. In the load-bearing configuration, the sail boom coupling section 23 may be fixed relative to the support 90 such that the sail boom coupling section 23 does not rotate relative to the support 90 thereby restricting movement of the sail boom 50 about the longitudinal axis X of the column 10. This therefore prevents the sail boom 50 from interfering with the derrick boom 70. If the support gear mechanism 110 is employed, then in the sailing configuration, rotation of the sail boom coupling section 23 relative to support 90 may be controllably driven by rotation of the first gear 111 (drive gear) that in turn drives rotation of second gear 112 (driven gear) that is fixed around the periphery of the sail boom coupling section 23. This therefore enables control of rotation of the sail boom 50 coupled to the sail boom coupling section 23 relative to the vessel that is fixed to the support 90. This is advantageous for ensuring efficient sailing. If the shaft gear mechanism 120 is employed, then in the sailing configuration, rotation of the alignment shaft 100 relative to the sail boom coupling section 23 may be controllably driven by driving rotation of the primary gear 121 (driver gear) that in turn drives rotation of the secondary gear 122 (driven gear). In the sailing configuration, the sail coupling section 24 may be fixed to the body 30 in the sailing position, which may in turn be fixed to the alignment shaft 100. The sail coupling section 24 is coupled to the first and second sail portions 61,62. Control of rotation of the alignment shaft 100 relative to the sail boom coupling section 23 therefore in turn enables control of rotation of the first and second sail portions 61,62 relative to the sail boom 50 in the sailing configuration. This may be advantageous for ensuring efficient sailing. If the support gear mechanism 110 is employed, then in the load-bearing configuration, the support gear mechanism 110 may prevent rotation of the sail boom coupling section 23 relative to support 90 by locking i.e. stopping / preventing rotation of the first gear 111. Consequently, rotation of the sail boom 50 relative to the support 90, and so relative to the vessel that the support 90 is fixed to, is prevented. This therefore prevents interference of the sail boom 50 with the load-bearing boom 70 during operation of the system 1 as a crane. If the shaft gear mechanism 120 is employed, then in the load-bearing configuration, rotation of the alignment shaft 100, and body 30 fixed thereto, relative to the sail boom coupling section 23 may be controllably driven by driving rotation of the primary gear 121. The sail boom coupling section 23 may already be fixed relative to the vessel by control of the support gear mechanism 110 as discussed above. Therefore, the shaft gear mechanism 120 may be used to controllably rotate the body 30, and so load-bearing boom 70 coupled to the body 30, relative to the vessel during load-bearing. To align the first base groove 20a with the first body groove 30a and to align the second base groove 20b with the second body groove 30b to reach the sailing position, the body 30 is rotated relative to the sail coupling portion 24, as discussed above. If the shaft gear mechanism 120 is employed, then the primary gear 121 may be rotated to cause rotation of the secondary gear 122. This in turn causes rotation of the alignment shaft 100, and body 30 fixed thereto, about the longitudinal axis X relative to the sail boom coupling section 23. During alignment of the grooves, the support gear mechanism 110 may be controlled to restrict rotation of the sail boom coupling section 23 relative to the support 90, and so restrict rotation of the sail boom 50. As the sail coupling section 24 is coupled to the sail boom 50 via the first and second sail portions 61,62, this in turn provides some restriction of rotation of the sail coupling section 24. It may also be desirable to further restrict rotation of the sail coupling section 24 by releasably lock the sail coupling section 24 to the sail boom 50 and / or the sail boom coupling section 23 during such alignment. Restricting rotation of the sail coupling section 24 about the longitudinal axis X may be helpful while the body 30 is rotated about the longitudinal axis X to align the first body and base grooves 20a, 20b and to align the second body and base grooves 20b, 30b. Figures 10 to 17 relate to a sailing crane system 1 ’ in accordance with a second embodiment of the claimed invention. The second embodiment is similar to the first embodiment and so will not be described in detail to avoid repetition. Only those features that are different between the two embodiments will be described below. The second embodiment differs from the first embodiment in that the load-bearing boom 70’ is configured differently and the upper portion 40 is not included. Unless expressly indicated otherwise, any other feature described in relation to the first embodiment is equally applicable to the second embodiment. For example, the body 30 and base 20 of the second embodiment are configured the same as the body 30 and base 20 of the first embodiment as described above. The configuration of the support 90 in respect of the first embodiment equally applies to the second embodiment. The description of the wing sail 60 and its coupling to the sail coupling section 24 of the base 20 and to the body 30 in the first embodiment equally applies to the second embodiment. The configuration of the sail boom 50 and its coupling to the sail boom coupling section 23 of the base 20 in the first embodiment equally applies to the second embodiment. The configuration of the shaft gear mechanism 120 and the support gear mechanism 110 in the first embodiment equally applies to the second embodiment. The second embodiment, as shown in Figures 11 to 20, differs from the first embodiment due to the different configuration of the load-bearing boom 70’. In the first embodiment, the load-bearing boom 70 is labelled as a derrick boom. In contrast, in the second embodiment, the load-bearing boom is labelled as a knuckle boom 70’. The knuckle boom 70’ is rotatably coupled to the body 30’. Optionally, knuckle boom 70’ is directly coupled to the body 30. The knuckle boom 70’ is configured to rotate between: (i) a stowed boom configuration in which the knuckle boom 70’ is coaxial with the longitudinal axis X of the column 10; and (ii) a load bearing configuration. The knuckle boom 70’ may be rotatably coupled to the upper end 32 of the body 30 at a body joint 33 about which the knuckle boom 70’ is rotatable. The knuckle boom 70’ may be pivotably coupled together at the body joint 33 that may be a pivot joint such that the knuckle boom 70’ remains in the same vertical plane as the body 30 while pivoting about the body joint 33. The knuckle boom 70’ may extend between a proximal end 71’ and a distal end 72’. The knuckle boom 70’ may be rotatably coupled to the upper end 32 of the body 30 at its proximal end 71’. Optionally, the knuckle boom 70’ comprises a proximal portion 74 comprising the proximal end 70a of the knuckle boom 70’ and a distal portion 75 comprising the distal end 72’ of the knuckle boom 70’. Therefore, the proximal portion 74 of the knuckle boom 70’ may be rotatably coupled to the upper end 32 of the body 30 at the body joint 33. The proximal portion 74 and the distal portion 75 are optionally rotatably coupled together at a knuckle joint 73 about which the proximal portion 74 is rotatably relative to the distal portion 75. The proximal and distal portions 74, 75 may optionally be pivotably coupled together at the knuckle joint 73 such that the proximal and distal portions 74, 75 remain in the same vertical plane while pivoting about the knuckle joint 73. The longitudinal axis L of the knuckle boom 70’ may be defined as the axis along the length of the knuckle boom (i.e. from the proximal end 71 to the distal end 72) when the proximal and distal portions 74,75 of the knuckle boom 70’ are coaxial with each other. The proximal and distal portions 74, 75 each have a respective longitudinal axis P, D. In the stowed boom configuration, as shown in Figures 12 to 15, the longitudinal axis P of the proximal portion 74, the longitudinal axis D of the distal portion 75 and the longitudinal axis X of the column 10 are coaxial. Accordingly, the longitudinal axis L of the knuckle boom 70’ (i.e. the axis of the knuckle boom 70’ from its proximal end 71 to its distal end 72 with the proximal and distal portions 74, 75 aligned) is coaxial with the longitudinal axis of the column 10 when in the stowed boom configuration. Therefore, with the knuckle boom 70’ in the stowed configuration, and the sail coupling section 24 and the body 30 in the sailing position, the knuckle boom 70’ and the sailing coupling section 24 and the body 30 of the column form a continuous mast that functions as a sailing mast. As shown in Figure 12, the knuckle boom 70’ optionally has the same cross-sectional shape as the body 30 and the sail coupling section 24 such that the sail coupling section 24, body 30 and knuckle boom 70’ together form a sailing mast having a generally continuous leading surface and generally continuous trailing surface when the column 10 is in the sailing configuration. In the exemplary version of the first embodiment shown, the sail coupling section 24 and the body 30 of the column 10 optionally has a D shaped cross section and so the knuckle boom 70’ similarly has a D shaped cross section with a curved, convex leading surface 70c and a planar trailing surface 70d. The knuckle boom 70’, similarly to the base 20 and body 30, is optionally formed as a hollow tubular section optionally with open proximal and distal ends 71,72. In the load-bearing configuration, the proximal portion 74 of the knuckle boom 70’ may be pivoted about the body joint 33 such that the proximal portion 74 is angularly displaced from the longitudinal axis Y of the body 30. The proximal portion 74 of the knuckle boom 70’ may be angularly be displaced by a non-zero angle from the longitudinal axis Y of the body 30 to reach the load-bearing configuration. Optionally, the proximal portion 74 of the knuckle boom 70’ may be displaced upto 90 degrees from the longitudinal axis Y of the body 30 such that proximal portion 74 remains above the body 30. The proximal portion 74 of the knuckle boom 70’ and the body 30 may have complementary engagement features that may be configured to releasably lock the body 30 and the proximal portion 74 with the longitudinal axis Y of the body 30 coaxial with the longitudinal axis P of the proximal portion 74. Those engagement means may be one or more pins and corresponding recesses. As best shown in Figures 16 to 20, in the load-bearing configuration, the distal portion 75 of the knuckle boom 70’ may be pivoted about the knuckle joint 73 such that the distal portion 74 is angularly displaced from the longitudinal axis P of the proximal portion 74. The distal portion 75 of the knuckle boom 70’ may be angularly be displaced by a non-zero angle from the longitudinal axis P of the proximal portion 74 to reach the load-bearing configuration. Optionally, the distal portion 75 of the knuckle boom 70’ may be displaced up to 180 degrees from the longitudinal axis P of the proximal portion 74. The distal portion 75 and the proximal portion 74 of the knuckle boom 70’ may have complementary engagement features (not shown) that may be configured to releasably lock the distal portion 75 and the proximal portion 74 with the longitudinal axis D of the distal portion 75 coaxial with the longitudinal axis P of the proximal portion 74. Those corresponding engagement features may be one or more pins and corresponding recesses. In such an arrangement, the sailing crane system T may be configured to operate as a knuckle boom crane having two joints (the body joint 33 between the proximal portion 74 and the body 30 and the knuckle joint 73 between the proximal portion 74 and the distal portion 75). Both the body joint 33 and the knuckle joint 73 being arranged on the same side such that the proximal portion 74 and the distal portion 75 rotate away from the longitudinal axis X of the column 10 in the same direction when moving from the stowed configuration to the load-bearing configuration. Optionally, the body joint 33 is arranged on the trailing surface 30d of the body 30 and the knuckle joint 73 is arranged on the trailing surface of the knuckle boom 70’. The pivoting about the body joint 33 and the pivoting about the knuckle joint 73 may be separately controlled. The angle at which the proximal portion 74 pivots about the body joint 33 may be separately controllable, and optionally different from, the angle at which the distal portion 75 pivots about the knuckle joint 73. As shown in Figures 19 and 20, the body joint 33 may comprise a hinge mechanism 130 comprising a first plate 131 and a first link 132 The first link 132 and the first plate 131 may be pivotably coupled together at the body joint 33. The first link 132 may be a first linear actuator. The first plate 131, as shown in Figures 19 and 20, may be configured as one or more plate(s) which are pivotably coupled to the first link 132. Where the first plate 131 is configured as multiple plates, those plates may be parallel. The first link 132 may comprise a first link bar (not shown) pivotably connected between the parallel plates. As shown in Figures 19 and 20, the first link 132 may be at least partially housed within the proximal portion 74 of the knuckle boom 70’ and the first plate 131 may be at least partially housed within the body 30. In the sailing configuration, the first link 132 may be wholly housed within the proximal portion 74 and the body 30, respectively. The first plate 131 may be housed partly within the body 30 and partly within the proximal portion 74 when the column 10 is in the sailing configuration. The end of the first plate 131 distal from the first link 131 is coupled to an inner surface of the housing / shell forming the body 30 such that its position relative to the longitudinal axis of the body 30 is fixed. The end of the first link 132 distal from the first plate 131 is coupled to an inner surface of the housing / shell forming the proximal portion 74 such that its position relative to the longitudinal axis of the proximal portion 74 is fixed. The first link 132 may pivot about the body joint 33 thereby pivoting the proximal portion 74 between its position in the stowed configuration (sailing configuration) with the longitudinal axis of the proximal portion 74 being coaxial with the longitudinal axis Y of the body 30 to the load-bearing configuration with the longitudinal axis of the proximal portion 74 being at a non-zero angle to the longitudinal axis Y of the body 30. When the first link 132 is formed as a first linear actuator, extension of the first actuator 132 causes the proximal portion 74 to pivot about the body joint 33 such that the proximal portion 74 pivots away from the longitudinal axis X of the column 10 (and away from the longitudinal axis Y of the body 30) such that the longitudinal axis of the proximal portion 74 is at a non-zero angle to the longitudinal axis Y of the body 30. The first actuator 132 can be controlled to control the angle at which the proximal portion 74 is pivoted away from the longitudinal axis X of the column 10 relative to the body 30. Similarly, retraction of the first actuator 132 causes the proximal portion 74 to pivot from the longitudinal X of the column 10 as the knuckle boom 70’ moves from the load-bearing configuration to the stowed configuration (sailing configuration). As shown in Figures 19 and 20, the knuckle joint 73 may comprise a linkage mechanism 140. The linkage mechanism 140 comprising a plurality of links 141,142,143. The plurality of links may comprise first, second and third links 141,142,143 where the first link 141 and the second link 142 are pivotably coupled together via the third link 143, the third link 143 being arranged between the first link 141 and the second link 82. The third link 143 may be pivotably connected to the knuckle joint 73. Movement of the first and second links 141,142 may cause the third link 143 to pivot about the upper pivot joint 43. The first link 141 may be a first linear actuator. The second link 142 may be a second linear actuator. The third link 143, as shown in Figures 19 and 20, may be configured as one or more plate(s) which are pivotably coupled each of the first and second links 141, 142. Where the third link 143 is configured as multiple plates, those plates may be parallel. The first link and / or second link may each comprise a first link bar (not shown) pivotably connected between the parallel plates. As shown in Figures 19 and 20, the first link 141 may be at least partially housed within the distal portion 75 of the knuckle boom 70’ and the second link 142 may be at least partially housed within the proximal portion 74 of the knuckle boom 70’. In the sailing configuration, the first link 141 and the second link 142 may be wholly housed within the distal portion 75 and the proximal portion 74, respectively. The third link 143 may be housed partly within the distal portion 75 and partly within the proximal portion 74 when the column 10 is in the sailing configuration. Part of the third link 143 may optionally extend through one or more slots in the housing / shell forming the distal portion 75 and / or the proximal portion 74 such that the knuckle joint 73 is arranged on the outer surface of the column 10. The remainder of the third link 143 not already extending through the slot(s) may be exposed when the distal portion 75 is rotated about the knuckle joint 73 on moving from the sailing configuration to the load-bearing configuration. The end of the first link 141 distal from the third link 143 is coupled to an inner surface of the housing / shell forming the distal portion 75 such that its position relative to the longitudinal axis of the proximal portion 74 is fixed. The end of the second link distal from the third link is coupled to an inner surface of the housing / shell forming the proximal portion 74 such that its position relative to the longitudinal axis of the proximal portion 74 is fixed. Movement of the first and second links 141, 142 causes the third link 143 to pivot about the knuckle joint 73 thereby pivoting the proximal portion 84 between its position in the stowed configuration (sailing configuration) with the longitudinal axis of the distal portion 75 being coaxial with the longitudinal axis of the proximal portion 74 to the load-bearing configuration with the longitudinal axis of the proximal portion 74 being at a non-zero angle to the longitudinal axis of the distal portion 75. When the first link 141 is formed as a first linear actuator and the second link 142 is formed as a second linear actuator, extension of the first actuator 141 and of the second actuator 142 causes the distal portion 75 to pivot about the knuckle joint 73 such that the distal portion 75 pivots away from the longitudinal axis X of the column 10 (and away from the longitudinal axis of the proximal portion 74) such that the longitudinal axis of the distal portion 75 is at a non-zero angle to the longitudinal axis of the proximal portion 74. The first and second linear actuators 141, 142 can be controlled to control the angle at which the distal portion 75 is pivoted away from the longitudinal axis of the proximal portion 74. Similarly, retraction of the first actuator 141 and of the second actuator 142 causes the distal portion 75 to pivot from the load-bearing configuration to the stowed configuration (sailing configuration). The knuckle boom 70’ may comprise a first knuckle boom groove 70a configured to receive the luff edge 61a of the first sail portion 61 and a second knuckle boom groove 70b configured to receive a luff edge 62a of a second sail portion 62 in use when the sailing crane system 1 is in the sailing configuration and the longitudinal axis U of the knuckle boom 70’ is coaxial with the longitudinal axis Y of the body 30. As shown in Figures 12 and 15, the first and second knuckle boom grooves 70a, 70b may extend along both the proximal and distal portions 74, 75. Optionally, the first and second knuckle boom grooves 70a, 70b extend along the entire length of the proximal and distal portions 74, 75. In the sailing configuration, the first body groove 30a, the first knuckle boom groove 70a and the first base groove 20a may together form a substantially continuous groove that is configured to receive the luff edge 61 a of a first sail portion 61. Consequently, in use, hoisting a first sail portion 61 may involve sliding the luff edge 61a of the first sail portion 61 along the substantially continuous groove formed by the first base groove 20a, first body groove 30a and the first knuckle boom groove 70a such that the luff edge 61 a extends longitudinally along the base 20, the body 30 and the knuckle boom 70’. Similarly, in the sailing configuration, the second base groove 20b is aligned with the second body groove 30b and the second body groove 30b is aligned with the second knuckle boom groove 70b so that the second base groove 20b, the second body groove 30b and the second knuckle boom groove 70b may together form a substantially continuous groove that is configured to receive the luff edge 62a of the second sail portion 62. Consequently, in use, hoisting the second sail portion 62 may involve sliding the luff edge 62a of the second sail portion 62 along the substantially continuous groove formed by the second base groove 20b, the second body groove 30b and the second knuckle boom groove 70b such that the luff edge 62b extends along longitudinally along the base, body and knuckle boom portions 20, 30,70. As best shown in Figure 15, the first knuckle groove 70a and the second knuckle groove 70b are optionally spaced apart along the trailing surface 70d of the knuckle boom 70’. The first and second knuckle grooves 70a, 70b are optionally formed along opposite edges of the trailing surface 70d of the knuckle boom 70’. The first and second knuckle grooves 70a, 70b are optionally formed as recesses in the outer edges of the trailing surface 70d of the knuckle boom 70’. In the exemplary embodiment shown, the column has a D-shaped cross section when in the sailing configuration. In the exemplary embodiment shown, the column 10 optionally has a D-shaped cross section when in the sailing configuration and so its leading surface 10c is optionally curved and its trailing surface 10d is optionally planar. Consequently, the leading surface 70c of the knuckle boom 70’ is optionally curved and the trailing surface 70d of the knuckle boom 70’ is optionally planar. The first and second knuckle grooves 70a, 70b are optionally formed as recesses in the outer edges of the trailing surface 70d that is optionally planar such that the luff edges 61a, 62a are substantially flush with the curved leading surface 70c of the knuckle boom 70’ when the sail portions 61,62 are hoisted. In use, to arrange the sailing crane system 1’ in the sailing configuration, the body 30 and the sail coupling section 24 are arranged in the sailing position by rotating the body 30 relative to the sail coupling section 24 such that the first body groove 30a is aligned with the first base groove 20a and the second body groove 30b is aligned with the second base groove 20b. The body 30 and the sail coupling section 24 may be releasably locked together in this sailing position, for example using complementary engagement features (not shown) such that the body 30 can no longer rotate relative to the sail coupling section 24. The proximal portion 74 of the knuckle boom 70’ is rotated about the body joint 33 and the distal portion 75 of the knuckle boom 70’ is rotated about the knuckle joint 73 to reach its stowed configuration where the longitudinal axes of the proximal and distal portions P, D are coaxial with the longitudinal axis Y of the body 30 (and with the longitudinal axis X of the column 10). The knuckle boom 70’ in its stowed configuration together with the column 10 provides a sailing mast of increased height thereby maximising the amount of wind power that can be harnessed when the column 10 together with the knuckle boom 70’ is used as a mast during sailing. The leading surface 70c of the knuckle boom 70’, the leading surface 30c of the body and the leading surface 20c of the sail coupling section 24 together forming a substantially continuous leading surface, which is optionally convex. The trailing surface 70d of the knuckle boom 70’, the trailing surface 30d of the body 30 and the trailing surface 20d of the sail coupling section 23 together forming a substantially continuous trailing surface, which is optionally planar. Therefore, the aerodynamics of the sailing mast formed by the column 10 and knuckle boom 70’ are improved, which may be important for the column 10 to function as an aerodynamic mast when in the sailing configuration. Furthermore, the knuckle boom 70’ does not interfere with the sail portions 61,62 when the knuckle boom 70’ is in the stowed configuration. In the sailing configuration, the first knuckle boom groove 70a’, the first body groove 30a and the first base groove 20a may together form a continuous groove configured for receipt of the luff edge 61a of the first sail portion 61. The second knuckle boom groove 70b’, the second body groove 30b and the second base groove 20b may together form a continuous groove configured for receipt of the luff edge 62a of the second sail portion 62. The first sail portion 61 may already be coupled at its luff edge 61a to the first groove 20a of the base 20 and at its leech edge 61b to the sail boom 50. The second sail portion 62 may already be coupled at its luff edge 62a to the second groove 20b of the base 20 and at its leech edge 62b to the sail boom 50. The first sail portion 61 may be hoisted from its furled or stacked position along the continuous groove formed by the first base groove 20a, first body groove 30a and first knuckle boom groove 70a such that the luff edge 61 a of the first sail portion 61 extends longitudinally along the base 20, the body 30 and the knuckle boom 70’ within the continuous groove. Mechanisms for hoisting sails is well known in the art. The second sail portion 62 may be hoisted from its furled or stacked position along the continuous groove formed by the second base groove 20b, second body groove 30b and second knuckle boom groove 70b’ such that the luff edge 62a of the second sail portion 62 extends longitudinally along the base 20, the body 30 and the knuckle boom 70' within the continuous groove. The first and second sail portions 61,62 therefore forming the wing sail 60 are spaced apart according to the spacing between the first and second grooves of the base 20a, 20b, between the first and second grooves of the body 30a, 30b and between the first and second grooves of the knuckle boom 70a’, 70b’. In use, the sail coupling section 24, the body 30 and knuckle boom 20, 30, 70’ may all be fixed together such that they cannot rotate relative to each other. The sail boom coupling section 23 may rotatably coupled to the support 90. The support 90 would be fixed the deck of the vessel such that the support 90 does not rotate relative to the deck of the vessel. The sail boom coupling section 23 may be rotatable relative to the sail coupling section 24, that rotation restricted by the coupling of the sail portions 61,62 to the sail boom at their leech edges 61b, 62b by one or more clews. Therefore, the sailing mast formed by the column 10 and the knuckle boom 70’ can rotate relative to the sailing vessel during sailing for enhanced aerodynamics. To change the sailing crane system 1 from the sailing configuration to the load-bearing configuration, the first and second sail portions 61,62 may be lowered within the continuous grooves such that they only remain coupled to the first and second base grooves 20a, 20b, respectively. The first and second sail portions 61,62 may be furled or stacked to arrive at their stowed configuration. Mechanisms for lowering and furling / stacking sails that may be employed are well known in the art. The distal portion 75 of the knuckle boom 70’ may be rotated about the knuckle joint 73 through a non-zero angle and the proximal portion 74 of the knuckle boom 70’ may be rotated about the body joint 33 such that the knuckle boom 70' reaches its load-bearing configuration where the longitudinal axis P of the proximal portion 74 of the knuckle boom 70’ is at a non-zero angle to the longitudinal axis Y of the body 30 and the longitudinal axis D of the distal portion 75 of the knuckle boom 70’ is at a non-zero angle to the proximal portion 74. The body 30 is unlocked from the sail coupling section 24, for example by disengaging the complementary engagement features (not shown), such that it can freely rotate relative to the sail coupling section 24 about the longitudinal axis X of the column 10. The knuckle boom 70’ may remain in the same vertical plane as the body 30 when in the load-bearing configuration. The angular displacement of the proximal portion 74 relative to the body 30, the angular displacement of the distal portion 74 relative to the proximal portion 74 and the rotation of the body 30 relative to the sail coupling section 24 can each be independently controlled thereby enabling adjusting both the height and position of the knuckle boom for receiving, lifting and manoeuvring loads. In the load-bearing configuration, the sail boom coupling section 23 is fixed relative to the support 90 such that it does not rotate relative to the support 90 or relative to the deck of the vessel thereby restricting movement of the sail boom 50 about the longitudinal axis X of the column 10. The support gear mechanism 110 and the shaft gear mechanism 120 described above in respect of the first embodiment may similarly be employed to control rotation of the alignment shaft 100 and body 30 fixed thereto and the sail boom coupling section 23, as discussed above in respect of the first embodiment. The claimed invention also relates to a kit comprising the column 10 as per any of the embodiments described above and the first and second sail portions 61,62 configured to form the wing sail 60 once hoisted with the column 10 in the sailing configuration. In any of the embodiments described above, although only shown in Figure 7, the load-bearing boom, which may be the derrick boom 70 or the knuckle boom 70’ may comprise one or more pulleys 200 and / or may comprise a hook 210 proximal to its distal end 72 configured to lift a load. In the embodiment employing a knuckle boom 70’, there may be a hook proximal to its distal end 72 and a hook proximal to the knuckle joint 73 that are each configured to lift a respective load. It will be appreciated that it is well known in the art how pulleys and hooks may be used to control lifting of loads. In any of the embodiments described above, the sailing crane system 1,1’ may further comprise a controller and one or more motors configured to control movement of components of the system 1,1’ when re-arranging the system 1,1’ between the sailing configuration and the load-bearing configuration or during use in the sailing configuration or load-bearing configuration. For example, the sailing crane system 1,1’ may comprise the controller and one or more motor(s) configured to control angular displacement of the load-bearing boom, which may be a derrick boom 70 or knuckle boom 70’, from the stowed configuration to the load-bearing configuration. The controller and one or more motor(s) may control angular displacement of the load-bearing boom, which may be the derrick boom 70 or knuckle boom 70’, while operating in the load-bearing configuration to change, for example, the height of the distal end of the load-bearing boom 70, 70’. The controller and one or more motors may also control rotation of the body 30 about the longitudinal axis X of the column 10. The controller and one or more motors may also control rotation of the sail boom coupling section 23 relative to the support 90. For example the controller and one or more motors may control the support gear mechanism 110 and / or the shaft gear mechanism 120. The controller and one more motors may control rotation of the body 30 about the longitudinal axis X of the column 10 independently of the angular displacement of the derrick boom 70 and / or knuckle boom 70’. The controller may be configured to control rotation of the body 30 relative to the sail coupling section 24 independently of the angular displacement of the load-bearing boom 70 that may be the derrick boom 70 or the knuckle boom 70’. The controller and one or more motors may also control the engagement and disengagement of complementary engagement features if employed. It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described above to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and / or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and / or configurations discussed. It will be understood that the embodiments described above in relation to Figures 1 to 21 are for the purposes of illustration only and that the invention is not so limited. The skilled reader will envisage various modifications and alternatives that fall within the scope of the claims. Both embodiments are described as having a base 20 employing a sail coupling section 24 and a sail boom coupling section 23 that are rotatably coupled together. Alternatively, the sail coupling section 24 and the sail boom coupling section 23 may be integrally formed. Both embodiments describe that the sail boom coupling section 23, the sail coupling section 24 and the body 30 are optionally coupled together by an alignment shaft extending entirely therethrough such that they remain coaxial when in the load-bearing configuration. However, the alignment shaft may only extend partially through the sail boom coupling section 23, partially through the body 30 and entirely through the sail coupling section 24. Although Figure 21 shows a single alignment shaft 100 used to couple together the sailing coupling section 24, the sail boom coupling section 23 and the body 30, multiple alignment shafts may instead be employed. As discussed above, the base and body 20, 30 are typically hollow thereby enabling the alignment shaft to extend therethrough. In an alternative embodiment, the base and body 20, 30 may be solid having longitudinal openings therethrough aligned with their respective longitudinal axes for receiving the alignment shaft 100 therein. Instead of an alignment shaft, other mechanisms for rotatably coupling together the body 30, the sail coupling section 24 and the sail boom coupling section 23 may be contemplated. The body 30 base 20, upper portion 40 and the knuckle boom 70’ are described as being hollow open-ended structures for minimising weight, which is important for efficient sailing. However, they can instead be hollow but employ end faces or they can be formed as solid structures. The body 30 and upper portion 40 are shown as tapering towards their upper ends and the loadbearing boom, which may be a derrick boom 70 and knuckle boom 70’, are also shown as tapering towards their distal end. This may be advantageous for stability when used as a crane in the loadbearing configuration and aerodynamics when used as a sailing mast in the sailing configuration. However, these portions may not be tapered. The body 30, base 20, upper portions 40 and the knuckle boom 70’ are shown as having a D-shaped cross section which is advantageous for aerodynamics. However, alternative cross-sectional shapes, such as circular may instead be employed where the reference to leading and trailing surfaces refers to the portion of the outer surface that is the front portion or rear portion in normal use. While the embodiments are advantageously configured for use with a wing sail 60 having first and second sail portions 61,62 that are received within the first and second base grooves 20a, 20b and first and second body grooves 30a, 30b, it is noted that the embodiments could instead employ a single groove in the body 30 and sail coupling section 24 such that they are configured for use with a single sail. However, such an arrangement would be significantly less efficient and aerodynamic for sailing. While the wing sail 60 has been described as having first and second sail portions 61, 62 that are flexible such that they can be furled or stacked when not in use, they may instead be rigid. Although the first and second base grooves 20a, 20b and first and second body grooves 30a, 30b are shown as being integrally formed in the sail coupling section 24 and body 30, respectively, which is advantageous for improving aerodynamics. The grooves 20a, 20b, 30a, 30b may instead be provided by tracks that are mounted to the edges of surfaces of the body and bases 20, 30. Similarly, although the first and second upper grooves 40a, 40b are shown as being integrally formed in the upper portion 40 in the first embodiment, which is advantageous for improving aerodynamics. The first and second upper grooves 40a, 40b may instead be provided by tracks that are mounted to the edges of a surface of the upper portion 40. Similarly, although the first and second knuckle grooves 70a, 70b are shown as being integrally formed in the knuckle boom 70’ in the second embodiment, which is advantageous for improving aerodynamics. The first and second knuckle grooves 70a, 70b may instead be provided by tracks that are mounted to the edges of a trailing surface of the knuckle boom 70’. In the versions of the first and second embodiments shown, the first and second body grooves 30a, 30b extend along the entire length of the body 30. However, the first and second body grooves 30a, 30b may instead extend only along part of the body 30. In the version of the first embodiment shown, the first and second upper grooves 40a, 40b extend along the entire length of the upper portion 40. Alternatively, the first and second upper grooves 40a, 40b may instead extend only along part of the upper portion 40. By way of a further alternative, the upper portion 40 may not comprise first and second upper grooves 40a, 40b. In the version of the second embodiment shown, the first and second knuckle grooves 70a, 70b extend along the entire length of the knuckle boom 70’. Alternatively, the first and second knuckle grooves 70a, 70b may instead extend only along part of the knuckle boom 70’, for example, only along the proximal portion 74. By way of a further alternative, the knuckle boom 70’ may not comprise first and second knuckle grooves 70a, 70b. The sail coupling section 24 is shown as having the same cross-sectional shape as the body 30 and, in the first embodiment, the upper portion 40, and, in the second embodiment, the knuckle boom 70’. This is advantageous for providing a column having continuous outer surfaces when in the sailing configuration. However, each of these portions may instead have different cross-sectional shapes. The sail boom coupling section 23 is shown as having a substantially circular cross-sectional shape but other cross-sectional shapes are contemplated. For example, the sail boom coupling section 23 may have the same cross-sectional shape as the sail coupling section 24. The figures show that the support 90 is configured to attached to the alignment shaft 100 by receiving the alignment shaft 100 in a support socket 90a employing projecting portions. However, other mechanisms for attaching the column 10 to the support 90 may be employed. Furthermore, the support 90 is optional and the alignment shaft 90 may instead be directly rotatably coupled to a deck of a vessel in normal use. The linkage mechanisms and hinge mechanisms employed in each of the first and second embodiments are optional and other mechanisms for pivotably coupling together components may instead be employed, such as hinges arranged between the components. The support gear mechanism 110 and the shaft gear mechanism 120 are optional and other mechanisms for controlling relative rotation of the components about the longitudinal axis X of the column 10 are contemplated. In the embodiments shown, the base and body 20, 30 are coaxial with the longitudinal axis X of the column in both the sailing configuration and the load-bearing configuration. However, the base 30 may be pivotably coupled to the sail coupling portion 24 such that the base 24 can pivot away from the longitudinal axis X of the column 10 in the load-bearing configuration. A similar mechanism to linkage mechanism 170 or hinge mechanism 130 may be employed to achieve pivoting of the body 30 relative to the sail coupling portion 24 such that the longitudinal axis Y of the base 30 may be at a non-zero angle to the longitudinal axis X of the column 10 when in the load-bearing configuration. Although the figures depict the derrick boom 70 being coupled to the trailing surface 30d of the body and the elongate recess 33 therefore also being formed in the trailing surface 30d of the body 30, the derrick boom 70 may instead be coupled to, and so the elongate recess 33 formed in, an alternative surface of the body 30, such as the leading surface 30a of the body 30. While receiving the derrick boom 70 within an elongate recess 33 such that the derrick boom is flush with the surface of the body 30 when in the stowed configuration, the elongate recess 33 is optional and instead the derrick boom 70 may be stowed such that the derrick boom 70 is parallel to the longitudinal axis of the body 30 and the distal end of the derrick boom 70 being adjacent to the surface of the body 30 to which the derrick boom 70 is attached. The derrick boom 70 is not limited to a specific shape and other shapes are contemplated. While the embodiments describe the upper portion 40 as being folded against the body 30 when in the load-bearing configuration, the upper portion 40 may instead be received telescopically within the body 30 when in the load-bearing configuration. The first embodiment depicts a column 10 having a base 20, body 30 and upper portion 40. As described above, the upper portion 40 is optional. According to the first embodiment, an additional portion of the column may be employed i.e. in addition to the base 20, body 30 and upper portion 40. For example, an additional portion may be rotatably coupled to an upper end 42 of the upper portion 40 of the column such that the additional portion is coaxial with the longitudinal axis X of the column 10 in the sailing configuration. The additional portion may be coupled to the upper end 42 of the upper portion by a pivot joint that that the additional portion is pivotable about. The additional portion may be pivoted about the pivot joint relative to the upper portion 40 when the column 10 moves to the load-bearing configuration such that the additional portion is no longer coaxial with the upper portion or with the longitudinal axis X of the column 10. The pivot joint may be arranged on an opposite side of the column to the upper joint 43 such that the additional portion may be folded to be adjacent to the upper portion 40 i.e. with its longitudinal axis parallel to the longitudinal axis of the upper portion 40 when the column is in the load-bearing configuration. The additional portion would therefore increase the overall height of the column 10 in the sailing configuration without increasing the overall height (and so potentially reducing stability) when in the load-bearing configuration. The column may not be limited as to the number of additional portions that may be rotatably coupled together. Optionally, the joints employed to rotatably couple the additional portions together may be arranged on alternating sides of the column 10 such that the additional portions may be folded against each other when the column 10 is arranged in the load-bearing configuration. The second embodiment employs a knuckle boom 70’ coupled to an upper end 32 of the body portion 30. The knuckle boom 70’ optionally employs two portions, a proximal portion 74 and a distal portion 75 that are pivotably coupled together at the knuckle joint 73. However, the knuckle boom 70’ may only employ the proximal portion 74. Alternatively, the knuckle boom 70’ may employ more than two portions that are each rotatably, optionally pivotably, coupled together at a respective joint. Optionally, each joint may be arranged on the same side of the column. Optionally, each portion may be arranged to be coaxial with the longitudinal axis of the column 10 when the knuckle boom 70’ is in the stowed configuration and each portion may be rotated about its respective joint to move to the loadbearing configuration where each portion is at a non-zero angle to an adjacent portion and to the longitudinal axis of the column 10. Each portion may optionally remain in the same vertical plane when pivoting about its respective joint. As used herein, the singular form of “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. The use of the term “comprising” is intended to be interpreted as including such features but not excluding other features and is also intended to include the option of the features necessarily being limited to those described. The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents.

Claims

1. A sailing crane system (1, 1 ’) comprising:a column (10) comprising a base (20) and a body (30);a sail boom (50) coupled to the base (20);a load-bearing boom (70, 70’) extending between a proximal end (71,71’) and a distal end (72, 72’), wherein the proximal end (71, 71’) of the load-bearing boom (70, 70’) is rotatably coupled to the body (30), the load-bearing boom (70, 70’) being configured to rotate between:(i) a stowed boom configuration in which a longitudinal axis (L) of the loadbearing boom (70, 70’) is aligned with a longitudinal axis (X) of the column (10); and(ii) a load-bearing configuration.

2. The sailing crane system (1, 1 ’) of claim 1, wherein the body (30) is rotatably coupled to the base (20).

3. The sailing crane system (1, T) of any preceding claim, wherein the base (20) comprises a sail boom coupling section (23) and a sail coupling section (24), wherein the sail boom coupling section (23) is coupled to the sail boom (50), wherein the sail coupling section (24) is configured to receive a luff edge of a sail portion in use, optionally wherein the sail boom coupling section (23) is rotatably coupled to the sail coupling section (24) such that the sail coupling section (24) is rotatable relative to the sail boom coupling section (23) about the longitudinal axis (X) of the column (10).

4. The sailing crane system (1, T) of claim 3, wherein the sail boom coupling section (23) is rotatably coupled to a support (90) configured to fix to a deck of a sailing vessel in use, wherein the sailing crane system optionally comprises engagement means configured to releasably lock the sail boom coupling section (23) to the support (90) to prevent relative rotation therebetween.

5. The sailing crane system (1, T) of any one of claims 2 to 4, wherein the sail coupling section (24) comprises a first base groove (20a) configured to receive a luff edge of a first sail portion in use,wherein the body comprises a first body groove (30a) configured to receive the luff edge of the first sail portion in use,wherein the body (30) is rotatable about a longitudinal axis of the column (10) relative to the sail coupling section (23) to a sailing position in which the first base groove (20a) is aligned with the first body groove (30a).

6. The sailing crane system (1, 1 ’) of claim 5,wherein the sail coupling section (24) comprises a second base groove (20b) configured to receive a luff edge of a second sail portion in use,wherein the body (30) comprises a second body groove (30b) configured to receive the luff edge of the second sail portion in use,wherein the body (30) is rotatable about its longitudinal axis relative to the sail coupling section (24) to the sailing position in which the second base groove (20b) is aligned with the second body groove (30b) such that the sailing crane system (1, 1 ’) is configured for use with a wing sail.

7. The sailing crane system (1, 1 ’) of any one of claims 5 or 6 further comprising engagement features configured to releasably lock the sail coupling section (24) relative to the body (30) in the sailing position.

8. The sailing crane system (1, T) of any one of claims 5 to 7, wherein the first body groove (30a) and the second body groove (30b) are spaced apart along a surface of the body (30).

9. The sailing crane system (1, 1 ’) of claim 8, wherein the body (30) comprises a trailing surface (30d), where the first body groove (30a) is formed along a first edge of the trailing surface (30d) and the second body groove (30b) is formed along a second edge of the trailing surface (30d).

10. The sailing crane system (1) of any one of claims 1 to 9, wherein the load-bearing boom (70, 70’) is a derrick boom (70) configured such that, in the stowed configuration, a distal end (72) of the load-bearing boom (70) is positioned adjacent to or received within the column (10).

11. The sailing crane system of claim 10 when dependent on claim 8 or claim 9, wherein a proximal end (71) of the derrick boom (70) is rotatably coupled to a part of the body (30) between the first body groove (30a) and the second body groove (30b).

12. The sailing crane system of claim 11 when dependent on claim 9, wherein the proximal end (71) of the derrick boom (70) is rotatably coupled to the trailing surface (30d).

13. The sailing crane system (1) of any one of claims 10 to 12, wherein the body (30) comprises an elongate recess (33) configured to receive a portion of the derrick boom (70) in use when in the stowed configuration.

14. The sailing crane system (1) of claim 13, wherein the elongate recess (33) is formed in a first surface of the body (30), optionally wherein the derrick boom (70) and the elongate recess (33) are configured such that, in use with the derrick boom (70) in the stowed configuration, the derrick boom (70) is received within the recess (33) such that the derrick boom (70) is flush with the first surface of the body (30).

15. The sailing crane system (1) of claim 13 or claim 14 when dependent on claim 11 or claim 12, wherein the elongate recess is arranged between the first body groove (30a) and the second body groove (30b).

16. The sailing crane system (1) of claim 15 when dependent on claim 12, wherein the first surface is the trailing surface (30d) of the body (30), optionally wherein the trailing surface (30d) is planar.

17. The sailing crane system (1) of any one of claims 1 to 16, wherein the column (10) further comprises an upper portion (40) rotatably coupled to an upper end (32) of the body (30) at an upper joint (43) about which the upper portion (40) is rotatable such that the upper portion (40) may be angularly displaced relative to the longitudinal axis X of the column (10).

18. The sailing crane system (1) of claim 17 when dependent on any one of claims 5 to 9, wherein the upper portion (40) comprises a first upper groove (40a) configured to receive a luff edge of a first sail portion in use,wherein the first upper groove (40a) is aligned with the first body groove (30a) when a longitudinal axis of the upper portion is coaxial with the longitudinal axis X of the column (10).

19. The sailing crane system (1) of claim 18 when dependent on any one of claims 6 to 9, wherein the upper portion (40) comprises a second upper groove (40b) configured to receive a luff edge of a second sail portion in use, wherein the second upper groove (40b) is aligned with the second body groove (30b) when a longitudinal axis of the upper portion is coaxial with the longitudinal axis X of the column (10).

20. The sailing crane system (1 ’) of any one of claims 1 to 9, wherein the load-bearing boom is a knuckle boom (70’) coupled to an upper end (32) of the body (30).

21. The sailing crane system of claim 20, wherein the knuckle boom (70’) comprises a proximal portion (74) comprising the proximal end (71’) of the knuckle boom (70’) and a distal portion (75) comprising the distal end (72’) of the knuckle boom (70’), wherein, in the stowed boom configuration, a longitudinal axis (P) of the proximal portion (74), a longitudinal axis (D) of the distal portion (75) and the longitudinal axis (X) of the column (10) are coaxial.

22. The sailing crane system of claim 21, wherein the proximal portion (74) and the distal portion (75) are rotatably coupled together at a knuckle boom joint (73) such that the distal portion (75) can be angularly displaced relative to a longitudinal axis (P) of the proximal portion (74).

23. The sailing crane system of claim 21, wherein the knuckle boom (70’) further comprises one or more intermediate portion(s) rotatably coupled between the proximal portion (74) and the distal portion (75).

24. The sailing crane system of any one of claims 20 to 23 when dependent on any one of claims 5 to 9, wherein the knuckle boom (70’) comprises a first knuckle boom groove (70a) configured to receive a luff edge of a first sail portion in use with the knuckle boom in the stowed boom configuration,wherein the first body groove (30a) is aligned with the first knuckle boom groove (70a) when the knuckle boom (70’) is in the stowed boom configuration.

25. The sailing crane system of claim 24 when dependent on any one of claim 6 to 9, wherein the knuckle boom (70’) comprises a second knuckle boom groove (70b) configured to receive a luff edge of a second sail portion in use with the knuckle boom in the stowed boom configuration,wherein the second body groove (70b) is aligned with the second knuckle boom groove (70b) when the knuckle boom (70’) is in the stowed boom configuration.

26. The sailing crane system of claim 24 or claim 25 when dependent on claim 9, wherein the knuckle boom (70’) comprises a knuckle boom trailing surface (70d) that is coplanar with the trailing surface (30d) of the body (30) when the knuckle boom (70’) is in the stowed configuration.

27. The sailing crane system (1, 1’) of any preceding claim, wherein the load-bearing boom (70, 70’) comprises one or more pulleys and / or comprises a hook proximal to its distal end (72) configured to lift a load.

28. The sailing crane system (1, 1 ’) of any preceding claim further comprising a motor configured to control angular displacement of the load-bearing boom (70, 70’) from the stowed configuration.

29. The sailing crane system (1, 1 ’) of any preceding claim when dependent on claim 3, wherein the body (30) is rotatably coupled to the sail coupling section (24) of the base (20), wherein the system further comprises a motor configured to control rotation of the body (30) relative to the sail coupling section (24) of the base (20).

30. The sailing crane system (1, 1 ’) of any preceding claim further comprising a wing sail (60), wherein the wing sail comprises a first sail portion (61) comprising a luff edge (61 a) and a leech edge (61b) and a second sail portion (62) comprising a luff edge (62a) and a leech edge 62b), wherein the luff edges (61a, 62a) of the first and second sail portions (61,62) are coupled to the sail coupling section (24) of the base (20) of the column (10).

31. A kit of parts comprising:the sailing crane system of any one of claims 1 to 30; and a wing sail (60) comprising a first sail portion (61) and a second sail portion (62).

32. A method of operating the sailing crane system of any one of claims 1 to 30, the method comprising:rotating the load-bearing boom (70, 70’) from the stowed boom configuration to the load-bearing configuration; and / orrotating the load-bearing boom (70, 70’) from the load-bearing configuration to the stowed boom configuration.

33. The method of claim 32 when dependent on claim 3 or any one of claims 3 to 30 when dependent on claim 3, wherein the method further comprises:rotating the body (30) relative to the sail coupling section (24) of the base (20).

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